Iowa geological survey, guidebook 25. living karst
LIVING IN KARST
Iowa Geological Survey
Guidebook Series No. 25
IOWA FIELD CONFERENCE FOR PUBLIC POLICY MAKERS
OCTOBER 11-12, 2005
Iowa Department of Natural Resources
Jeffrey R. Vonk, Director
The collapse of rock and soil into underground
crevices and caves causes sinkholes (circular pits)
in regions of shallow limestone.
Aerial photo over Clayton County
by Gary Hightshoe,
Iowa State University
Printed in-house on recycled paper.
LIVING IN KARST
Iowa Geological Survey
Guidebook Series No. 25
IOWA FIELD CONFERENCE FOR PUBLIC POLICY MAKERS
OCTOBER 11-12, 2005
Robert D. Libra
With contributions by
Northeast Iowa RC & D
Iowa DNR-Geological Survey
Iowa DNR-Solid Waste
Iowa DNR-Geological Survey
Iowa DNR-Water Monitoring
Northeast Iowa RC & D
U.S. Fish and Wildlife Service
Iowa DNR-Parks & Recreation
Winneshiek County Landfill
Nat. Res. Cons. Service
Nat. Res. Cons. Service
Iowa DNR-Field Office #1
Iowa DNR-Field Office #1
Iowa DNR-Water Monitoring
Iowa DNR-Water Monitoring
Iowa DNR-Field Office #1
Iowa Department of Natural Resources
Jeffrey R. Vonk, Director
TABLE OF CONTENTS
STOP 1. Phelps Park – The Northeast Iowa Landscape and Water Quality .
STOP 2. Dunning Spring Park – Karst, Water Quality, and Economics
STOP 3. Skyline Quarry – The View from Inside an Aquifer
STOP 4. Decorah Hatchery – Trout Production and Water Quality .
STOP 5. Winneshiek County Landfill – Solid Waste in Karst .
STOP 6. Hecker Creek – Losing Streams
STOP 7. Postville Industrial Wastewater Treatment Plant – Wastewater
and Water Quality .
STOP 8. Glenwood Cave – Caves in Iowa .
STOP 9. Enyart Farm – AFOs in Karst Part 1 .
STOP 10. Forestry Planting – Alternative Land Use .
STOP 11. Thompson-Reisinger Farm – AFOs in Karst Part 2
STOP 12. Rossville County Park – Stepping Inside a Sinkhole
STOP 13. Lower Yellow River – Watersheds and Water Quality
STOP 14. Effigy Mounds – Northeast Iowa and the Mississippi River
Many people assisted in the preparation of the field conference and guidebook. Those listed
herein without affiliation are Iowa DNR staff. Contributors providing written work are listed
on the title page. In particular, Joe Sanfilippo, Bill Kalishek, Lora Friest (NE IA RC&D), Luann
Rolling (NRCS-Allamakee County), John Pearson, and Bruce Blair provided significant input
to the trip design and details. In addition, Paul Van Dorpe organized the logistics for the trip.
Jim Janette (Allamakee County Conservation Board) Gary Shawver (Shawver Well Com-
pany), and Gene Tinker provided expertise at trip stops. Ray Anderson and Adam Kiel (NEIA
RC&D), and in particular Calvin Wolter prepared many of the illustrations. Pat Lohmann
formatted the guidebook and provided expertise on the graphics and design. Lois Bair, Chad
Fields, Chris Kahle, Eric O'Brien, Lynette Seigley, and Calvin Wolter served as reviewers for
the guidebook. Sharon Tahtinen, Mary Pat Heitman, Lois Bair, Karyn Stone, Lisa Ogle, and
Tammie Krausman provided administrative support. Wayne Gieselman and Jeff Vonk
provided management support. Finally, we acknowledge the numerous landowners who
provided access to their property, and to the field conference participants.
Areas in the state with varying levels of karst development and potential.
The Karst Landscape of Northeast Iowa
Bob Libra, State Geologist, Iowa Department of Natural Resources (DNR)-Geological Survey
A variety of geologic factors have produced the karst, shallow rock, high relief landscape ofnortheast Iowa. First, Paleozoic age carbonate (limestone and dolomite) rocks form theuppermost bedrock over much of the area. These carbonate strata are broken into varioussized "blocks" by vertical fractures and roughly horizontal bedding planes. As groundwatercirculates through these cracks, it slowly dissolves the rock away, creating wide fractures,pipes, voids, and caves. Second, erosion has removed much of the glacial deposits that oncecovered the landscape, leaving the carbonate rocks near the surface, typically within 25 feet,and often within 10 feet. When rock that contains voids and openings is combined with a thincover of soil, the soil may collapse into the rock openings, producing sinkholes. Finally, theproximity of this area to the deeply-cut Mississippi River Valley has resulted in steep, deepstream valleys.
These solutionally modified karst-carbonate rocks are excellent aquifers. They are capableof transmitting large quantities of groundwater at quite fast rates. However, the presence ofsinkholes allows surface runoff and any associated contamination to directly enter these rockstrata. When sinkholes or enlarged fractures occur in stream valleys and other drainage ways,entire streams may disappear into the rock. These streams are called "losing streams." Inaddition, "between the sinkholes," the thin soil cover provides much less filtration ofpercolating water than occurs elsewhere in the state. These factors make the aquifers, andwater wells tapping them, very vulnerable to contamination, and allow any contaminants thatreach the aquifer to spread long distances very quickly – especially by groundwaterstandards.
Water – and any contaminants – enter karst-carbonate aquifers via sinkholes, losing streams,and by infiltration through the shallow soils in flat upland areas. The water travels throughcracks and voids to the water table, below which all voids are water-filled. The groundwaterthen travels "down-flow" through the broken rocks to springs and seeps along the deeply cutstream valleys. These springs and seeps supply much of the stream flow in shallow rockareas. The carbonate aquifers are underlain by less transmissive rocks, called confining beds,which act as the "bottom seal" of the aquifer. Springs and seeps are most prominent wherethe contact between the aquifer and the underlying confining bed is exposed in valleys.
Karst conditions affect other parts of the state. Figure 1 shows areas in the state with varyinglevels of karst development and potential. However, the most visibly developed karst occursin northeast Iowa. Figure 2 is a generalized stratigraphic column for northeast Iowa, showingthe sequence of rocks that underlie the area. Figure 3 is a generalized geologic map showingwhere the various rock units form the uppermost rock. The unit called the Galena Limestoneis the most karst-affected unit. In particular, most of the sinkholes and large springs in thisarea are formed in this unit. The unit called the Prairie du Chien Dolomite is another carbonateunit that exhibits voids and dissolved fractures, but few sinkholes. We will be referring to therock column and geologic map throughout the trip to keep ourselves geographically andgeologically located.
Figure 2. Generalized stratigraphic column of northeast Iowa.
Figure 3. Generalized geologic map of northeast Iowa showing field conference stops.
Table 1-1. Algific slope snails and plants.
Iowa Pleistocene Snail
Minnesota Pleistocene Ambersnail
Novisuccinea sp. A
Iowa Pleistocene Ambersnail
Novisuccinea sp. B
Briarton Pleistocene Vertigo
Midwest Pleistocene Vertigo
Iowa Pleistocene Vertigo
Vertigo new species
Northern Wild Monkshood
Limestone Oak Fern
Gymnocarpium robertianum Special Concern
1) State status definitions. Endangered: likely to become extinct in state, protected by state law;
Threatened: likely to become Endangered in state, protected by state law; Special Concern:in need of study of distribution and status in state, not protected by state law.
2) Federal status definitions. Endangered: likely to become extinct in all or a significant portion
of its total range. Threatened: likely to become Endangered in all or a significant portionof its total range. Threatened and Endangered plants are protected by federal law onfederal lands; Threatened and Endangered animals are protected by federal law throughouttheir national range.
Phelps Park – The Northeast Iowa Landscape and Water Quality
Our first stop, Phelps Park, overlooks the Upper Iowa River Valley from a cliff-like hillsideformed by Galena Limestone. These rocks are also visible in numerous road cuts through thehills in the Decorah area. From river level to the top of the bluffs at Phelps Park, most of theGalena Limestone is on display. Unlike the roadcuts, the exposures here are natural, formedby the down cutting of the Upper Iowa River. Natural exposures are often vegetated, andbecause of the karstic nature of the Galena Limestone, this vegetation may be quite unique– as is the case in Phelps Park.
Algific Talus Slopes: A Special Natural Habitat
in the Karst Landscape of Northeast Iowa
John Pearson, Botanist, Iowa DNR-Parks & Recreation Division
Karst – the fractured limestone and dolomite bedrock that underlies the landscape acrossmuch of northeast Iowa – displays interesting geologic, topographic, and hydrologic features.
Under specialized circumstances, it can also support a rare biological habitat known as an"algific talus slope." To understand this term, let's examine its components:
"Slope"– in this case, the term is referring to steep, rocky hillsides, usually north-facing,
forested, and deeply shaded.
"Talus"– rock piles comprised of cobbles and boulders that have tumbled from rock
outcrops and accumulated at the bottom of cliffs and steep hillsides. When talus is composedof large, irregularly shaped rocks, air can move through vents formed by gaps and holes.
"Algific"– a technical term meaning "cold air." During winter, shallow groundwater in
fractured bedrock freezes; during summer, cold air from the slowly melting ice seeps outwardfrom bedrock, flows through talus, and emerges onto the surface, especially through vents.
The flow of cool, moist air over the surface of algific talus slopes creates an unusualmicroclimate, simulating the regional climate that prevailed over Iowa and the Midwest at theend of the Pleistocene ice age thousands of years ago. As the regional climate warmed atthe end of the ice age, Iowa became uninhabitable for plants and animals adapted to the coldclimate; many of these species are now found in the boreal forests of Canada. However, dueto their unique geologic setting, algific talus slopes (each generally less than one acre in size)maintained small pockets of cold microclimate within the warming macroclimate. Althoughnot large and contiguous enough to support the full flora and fauna of the original boreal forest,algific talus slopes do harbor relict populations of several plant and animal species, mainlysnails and wildflowers, typical of colder climates.
In the United States, algific talus slopes are rare, primarily occurring as small, scatteredremnants. Many of the snail and plant species of algific talus slopes are found solely in thishabitat (Table 1-1). Reflecting their national rarity, two of them are also federally listed: theIowa Pleistocene Snail (Endangered) and Northern Wild Monkshood (Threatened).
Maintaining these plants and animals as viable members of Iowa's flora and fauna will requireprotection of their unique algific habitat. Fortunately, due to their locations on steep, rockyhillsides, most algific talus slopes are generally unsuited for roads, houses, and cropfields andare naturally "safe" from development. However, some algific talus slopes have beenunknowingly damaged by construction of roads, powerlines, and fences, as well as byroadside spraying and heavy grazing. In addition to the algific talus slopes themselves,sinkholes on nearby uplands also need protection from dumping of wastes because waterentering sinkholes can re-emerge in algific talus slopes.
A cooperative effort among the Iowa Department of Natural Resources, the U.S. Fish andWildlife Service, The Nature Conservancy, and various county conservation boards toprotect algific talus slopes has resulted in the acquisition of several high-priority sites. Inparticular, several key properties have been purchased from willing landowners and placedunder the protective stewardship of the Driftless Area National Wildlife Refuge, a uniquerefuge dedicated to federally listed species of algific talus slopes. As one of its environmentalprotection efforts, the Iowa Department of Natural Resources maintains a statewidedatabase on the known locations of endangered, threatened, and special concern species –including those inhabiting algific talus slopes – and uses this information to alert developersof potential conflicts before work commences. Experience has shown that minor adjustmentsto the design of projects generally avoid impacts to rare natural habitats. Increasingawareness of the value and fragility of algific talus slopes among land managers and the publicin general will ensure the perpetuation of these interesting natural features into the future.
Decorah's Water Supply
Dave Pahlas, Supervisor, City of Decorah Water and Sewer
The City of Decorah has endorsed and supported the goals of the Upper Iowa WatershedProtection Project since its inception in 1999. This support is evidenced by assistance fromCity employees in collecting water samples and annual monetary contributions.
There are several significant concerns that have propelled the City's interest in workingcooperatively with State and Federal agencies on water issues. One prime example involvesthe increasing nitrate levels in the Upper Iowa River and our city wells over the last thirtyyears. Although analysis of the data does not indicate a direct correlation between nitratelevels in the river to levels within the City wells, the importance of continuous intergovern-mental cooperation leading to highly credible conclusions may very well enable theimplementation of more effective preventive measures.
An experience that began in 1992 with the PCE contamination of two City wells also servesto illustrate the success resulting from solid cooperation and meaningful communication.
Arrangements with the Iowa DNR led to the availability of resources from the HazardousRemediation Fund. Through a clear but sufficiently flexible agreement, the City managed thecleanup while working closely with the DNR in monitoring the effectiveness of this effort.
By 1997, one well was placed back in service while the second well was producing water withno detectable levels of the PCE within two years.
A third example of beneficial cost-sharing arrangements can be found in the City's on-goingrelationship with the U.S. Geological Survey in our mutual need for stream-flow data and river
stage information. This kind of cooperative venture encourages interested parties to sharevaluable data. In that process, those parties charged with various responsibilities involvingwatershed management avail themselves of greater amounts of data with concomitant cost-saving measures.
Of course, many water quality concerns require a medium to long-term horizon with regardto the collection and verifiable analysis of the data. The general Decorah area perhapswarrants extraordinary diligence due to the shallow aquifers, the karst topography with itsparticular vulnerabilities, and the unique characteristics of our aquifers. While appreciatedalong with other features of our surrounding environs, these distinctions cause us to perhapsmore vividly recognize the challenges and rewards that cooperative efforts can bring inmonitoring and preserving water quality.
Sources of Bacteria in the Upper Iowa River: Water Quality and DNA
Eric O'Brien, Biologist, Iowa DNR-Geological Survey Water Monitoring
Mary Skopec, Supervisor, Iowa DNR-Geological Survey Water Monitoring
The Upper Iowa River and its watershed are valuable natural and economic resourceslocated in extreme northeast Iowa and southeast Minnesota. The Upper Iowa Riverwatershed is a 1,005-square-mile watershed recognized by the U.S. Environmental Protec-tion Agency and the State of Iowa as a priority watershed for water quality protection. Thisriver system is heavily utilized for swimming, tubing, and canoeing. The river has a varietyof water quality issues. Some reaches of the river were placed on Iowa's Impaired WatersList in 2004. Concentrations of the indicator bacteria E. coli exceed state standards for bodycontact in recreational waters. Efforts to lower bacteria levels need information on thesource(s) of the bacteria. In the Upper Iowa Watershed, this involves knowing where thewater sources are. The presence of sinkholes and losing streams, which may contributebacteria-laden runoff to the complex groundwater system, complicates the question of wherethe bacterial sources are located. Further, in all our watersheds, there are questions as to thebiological sources of bacteria. Are they from human waste, livestock manure, or wildlife? Inan attempt to address the latter question, the DNR's Water Monitoring Program, inconjunction with the University of Iowa Hygienic Laboratory and Upper Iowa RiverWatershed Alliance, began efforts to use DNA identification techniques to determine thesources of bacteria impairing the river.
One such technique is DNA ribotyping, which involves comparing DNA patterns or
"fingerprints" of E. coli bacteria from affected waters to DNA fingerprints of E. coli from
known sources of fecal material in the watershed. Researchers believe that the DNA of
bacteria taken from fecal matter may vary substantially from one watershed to the next.
Therefore, the collection of known sources of fecal material in a particular watershed is
necessary to generate a DNA fingerprint database or library for the watershed for
comparison with unknown bacteria in the water.
The Upper Iowa River Watershed Alliance has monitored 39 stream sites throughout theUpper Iowa River Watershed since 1999 in an effort to identify sub-watersheds that arecontributing elevated levels of fecal indicator bacteria to the Upper Iowa River. The waterquality monitoring identified six sub-watershed tributaries that had elevated bacteria levels.
Three of the six tributaries were selected for a bacteria source tracking project: Coldwater
Figure 1-1. Water monitoring locations for DNA source tracking analyses.
Creek, Silver Creek near Cresco, and Silver Creek near Waukon. Potential bacteria sourcesin these sub-watersheds include runoff from feedlot and manure-amended agricultural lands,inadequate septic systems, and wildlife.
The Upper Iowa Bacteria Source Tracking Project, begun in 2002, used DNA ribotyping toidentify sources in the Upper Iowa River Watershed and initiated the establishment of astatewide E. coli bacteria DNA database. A total of 259 E. coli isolates from known manuresources (e.g., hog, cattle, sheep, goose, raccoon, deer, and human) were collected andanalyzed to build a statewide ribotyping library with patterns from known Iowa strains. Afterobvious outliers were removed, the following E. coli strains were used in the identification ofsources in the three Upper Iowa sub-watersheds: cattle (88), deer (35), human (27), geese(26), and swine (24). DNA ribotyping was performed on 50 E. coli strains from water samplestaken from the three sub-watersheds in Coldwater Creek, Silver Creek near Cresco and SilverCreek near Waukon (see Figure 1-1). When looking at the bacteria in the water and comparingit to the DNA database, it was noted that human, cattle, and other animal fecal material wereall present in the water. DNA ribotyping successfully discriminated between human and cattlebacterial sources. However, the number of E. coli strains was insufficient to distinguishbetween the other animal sources.
Dunning Spring Park – Karst, Water Quality, and Economics
Dunning Spring issues from near the base of the Galena Aquifer. The much less permeableDecorah Shale - the confining bed "floor" for the aquifer - is near the land surface, forcingthe water to discharge from the wall of the Upper Iowa River Valley. The result is thepicturesque falls. The groundwater issuing from the spring is flowing through an open,cavernous conduit, formed by the solutional enlargement of fractures. Solutionally modifiedfractures and cracks are the most common characteristic of karst. The water from this (andmost larger springs in the area) maintains a fairly constant temperature of about 45 degreesF most of the year. Exceptions occur after snowmelt or heavy rains when colder or warmerwater rapidly enters the aquifer via sinkholes and losing streams. About 50 feet below ourfeet is the contact between the Decorah confining bed and the underlying St. PeterSandstone. Figure 2-1 shows the area around Dunning Spring, with sinkholes mapped to thenorth. Our next stop, Skyline Quarry, is also visible.
Northeast Iowa Economics: Tourism, Agriculture, and Water Quality
Lora Friest, Northeast Iowa Resource Conservation and Development (RC&D)
Northeast Iowa communities balance the economics of agriculture and tourism everyday. Onone side of the scale is a strong agricultural community with a rich heritage that includeshundreds of small livestock and dairy producers managing hay and pasture on steep highlyerodible slopes. On the other side of the scale is a burgeoning recreation and tourism industrythat capitalizes on the beautiful and unique features found in the rolling hills of Northeast Iowa,and the coldwater fisheries and streams that flow through them. The marriage of these twoindustries creates a balanced, diverse economy, but it also creates an environment for conflictwhen one industry tries to dominate the resources or when shifts in one industry negativelyimpact the other. This stop will give you some food for thought, provide hard numbers aboutthe economic benefits of each industry, and open discussion on how easily shifts in one cansignificantly impact the other. It will also give participants an opportunity to think about thepotential future of recreation/tourism and agriculture in a landscape where surface water andgroundwater moves through watershed systems faster than anywhere else in the state.
Northeast Iowa Trout Streams
Bill Kalishek, Biologist, Iowa DNR-Fisheries
All of Iowa's 105 trout streams are located in 10 counties in the northeastern part of the state.
Trout have a water temperature requirement that restricts their distribution in Iowa. Ingeneral, trout cannot survive in water greater than 75 degrees. Most Iowa waters will reachmaximum summer water temperature of greater than 80 degrees. The only waters that staycold enough during the summer to support trout are the spring-fed streams that drain fromthe karst topography of northeast Iowa.
A coldwater trout stream is a very complex natural system. The quality of the stream isaffected by the underground aquifer that forms the spring flow, the surface watershed that
drains into the stream, the land use immediately along the stream and the physicalcharacteristics in the stream itself. High quality trout streams result from successfulpartnerships between private landowners and conservation agencies in the management ofthese natural resources.
Trout fishing is a major economic force in northeast Iowa. It is estimated that anglerexpenditures for all Iowa coldwater trout fisheries total $13.9 million per year. This estimateis based on data from the U.S. Fish and Wildlife Service and Iowa DNR surveys of Iowa troutanglers that were conducted in 2001. The American Sportfishing Association's report"Sportfishing in America" indicated the retail sales related to all fishing in Iowa was $356million and total economic output from these sales was $728 million.
Topographic map of Dunning Spring–Skyline Quarry area with sinkholes.
Skyline Quarry – The View from Inside an Aquifer
Bob Libra, State Geologist, Iowa DNR-Geological Survey
Skyline Quarry is owned and operated by Bruening Rock Products Inc. The GalenaLimestone is quarried here. As you enter the quarry, you are in essence "stepping into" theGalena Aquifer. Visible in the quarry walls are nearly vertical fractures and nearly horizontalbedding planes that have been solutionally enlarged to varying degrees. These are thepathways that groundwater flows through. The rock "matrix" itself has little permeability andtransmits little groundwater. As the groundwater is forced to flow through only a smallpercentage of the rock, it moves relatively fast. Where large, open, cavernous conduits arepresent, dye traces have shown flow rates ranging from miles per hour following rainstormsto thousands of feet per day during dry periods. The larger voids act as drains for the aquifer,and groundwater within smaller openings and fractures follows the path of least resistance,moving towards the larger voids. Geologists spend much time explaining that groundwaterisn't contained in underground rivers. However, in karst aquifers the underground riveranalogy isn't that far off; major conduits are like the main stem of a river, and the smaller voidsand fractures are like a three-dimensional web of tributaries. This is in contrast to sand, gravel,and sandstone aquifers, where groundwater movement is more uniform throughout theaquifer, and much slower as it works its way between the individual sand and gravel particles.
At the top of the quarry walls, only a thin cover of unconsolidated soils are present. Beneaththis thin soil mantle, fractures widen. This is the result of void formation near the top of thebedrock, a common occurrence in karst that marks the first steps towards sinkhole formation.
A larger sinkhole is also exposed in cross-section by the quarry walls. The combination of athin soil cover that offers limited filtration and protection from any contamination indownward-percolating soil water, sinkholes which capture surface runoff and direct it intothe aquifer, and essentially no removal of contaminants from the fast moving groundwaterin the fractures results in common water quality problems in the Galena Aquifer. As thisaquifer supplies much of the "baseflow" for area streams, any contamination is delivered tothe streams as well.
Long-term groundwater monitoring has been conducted at Big Spring, which drains a 100-square-mile area underlain by the Galena Limestone in Clayton County. On average over15,000 gallons per minute of groundwater discharges from Big Spring to the Turkey River.
For comparison, this is a little over one-half of the average amount of water produced by theDes Moines Water Works. Land use in Big Spring's "groundwater-shed" is essentially allagricultural. Typically, 45-50% of the land is in corn production and 35-40% is used to raisealfalfa. Small dairy and hog operations are common. Concentrations of nitrate-N at Big Springcommonly are near the 10 mg/L U.S. EPA drinking water standard. Low levels of atrazine(0.1 to 1.0 ug/L) are typically present, along with 200 to 300 ug/L of phosphorus. Fecalbacteria levels are commonly in the hundreds to thousands of colonies/100 ml. Concentrationsof phosphorus, bacteria, and herbicides are generally 1-2 orders of magnitude greaterfollowing major rainfall events. These data point out the vulnerability to contamination of thisproductive karst aquifer.
Figure 4-1. Geologic map of the Trout Run watershed area.
Decorah Hatchery – Trout Production and Water Quality
The Decorah Hatchery is fed by Siewers Spring, which discharges groundwater from theGalena Limestone to Trout Run Creek. The Trout Run watershed is shown in Figure 4-1.
Relatively few sinkholes are shown on the county soil survey for the watershed, althoughmore are known to exist. Losing stream segments have also been observed, some which draininto sinkholes. Many more sinkholes occur in the watershed to the east, and these maycontribute water to the spring as well.
The Decorah Hatchery
Karen Osterkamp, Biologist, Iowa DNR-Fisheries
Decorah State Trout Hatchery, built in the early 1930s, was originally "Siewers Spring BassHatchery." Smallmouth bass and northern pike were reared in earthen ponds and trout inconcrete raceways. Beginning in 1978, the hatchery concentrated entirely on producingcatchable–sized trout. Today, nearly 300,000 trout pass through the hatchery each year.
Siewers Spring is also the source of Trout Run Creek, a high priority coldwater stream.
Civilian Conservation Corps constructed a retaining dam of masonry rock impounding thespring in 1934. A flume connecting the impounded water diverted water into ten one-acreearthen ponds. The underground water source of Siewers Spring supplies 48-50 degree wateryear round at a rate of 3,000 to 5,000 gallons per minute, yielding ideal temperatures andquantity for trout rearing. The approximately 23,000-acre watershed south of the hatcheryrecharges the spring. Although the quantity of water from Siewers Spring has always beendependable, during rainfall events the sinkhole-driven water source can be contaminated byheavy silt loads and high concentrations of nitrogen gas. These runoff events plagued thehatchery causing severe fish mortality and health problems, and fish production and efficiencywas greatly impacted.
The hatchery was renovated in 1988-1989 with Sport Fish Restoration and Iowa Fish andWildlife Trust funds. Approximately 2.4 million dollars was spent to build a spring waterclarifier basin, degassing tower and oxygen injection system to compensate for the poor waterquality emerging from Siewers Spring. In addition, four vertical turbine pumps were installedto supply twenty-four new concrete raceways and three lined ponds. The new facility iscapable of mitigating some of the water quality problems by allowing much of the silt to settleout before entering the rearing raceways. However, compared to the original gravity flowhatchery, the new facility needs more maintenance and has increased demand for electricitybecause of the additional equipment required to run it.
Problems with fish health are still directly related to runoff events and necessitate costlytreatments to minimize disease outbreaks. It is apparent that additional improvements in thewatershed will have a positive impact on fish health, which is closely tied to the quality ofSiewers Spring's water as it enters the facility.
Figure 5-1. Color infrared photo of landfill area.
Winneshiek County Landfill – Solid Waste in Karst
The Winneshiek County landfill lies within a few miles of some of the most karst-affectedareas in the state. We passed sinkholes as we approached the landfill driveway. How cana landfill be in such a setting? Relatively subtle changes in the underlying geology occur aswe reach the landfill area. Here, more slowly permeable shale and shaley carbonate rocksof the Maquoketa Formation overlie the Galena Limestone. The Maquoketa rocks are lessprone to fracturing and karst formation, although the lowermost part of the formation doesexhibit some sinkholes. Also, there is a somewhat greater thickness of glacial deposits here.
Taken together, these deposits provide suitable materials for the landfill cells. Figure 5-1shows the landfill, nearby sinkholes, and the outcrop area of the Galena Limestone.
Landfills in Iowa
Jeff Myrom, Iowa DNR-Solid Waste
Iowa has 59 permitted Municipal Solid Waste Landfills (MSWLFs). Of these, 5 are privatelyowned and 54 are owned by cities, counties, or a collection of local governments through a28E agreement. No new MSWLF has been sited in Iowa since the 1980s. To increasedisposal capacity, most MSWLFs now pursue a combination of vertical and horizontalexpansions from existing disposal cells.
Approximately half of Iowa's 59 MSWLFs meet the minimum federal standards for linersand leachate collection systems specified in 40 CFR 258, commonly referred to as RCRASubtitle D standards. However, by October 1, 2007, all operating MSWLFs in Iowa must havea composite liner (2 feet of clay compacted to 1x10-7 cm/sec permeability and a flexibleplastic liner over top of that) or an approved alternative liner (typically 4-5 feet of claycompacted to 1x10-7 cm/sec permeability).
Of the 29 RCRA Subtitle D compliant MSWLFs, 16 use composite liners and 13 usealternative liners. Furthermore, it appears that most of the 30 non-compliant MSWLFs willconstruct new, adequately lined disposal cells before the October 1, 2007 deadline. At thistime, only 3 non-compliant MSWLFs have elected to close.
John Hogeman, Winneshiek County Landfill Operator
Joe Sanfilippo, Supervisor, Iowa DNR-Manchester Field Office
The Winneshiek County Sanitary Landfill opened for business in 1974 as a private operation.
The landfill property, including the ground, equipment and landfill engineering plans were theproperty of Nishna Sanitary Service. Nishna operated in Winneshiek County under limitedcontrol by the Winneshiek County Board of Supervisors. In 1991 Winneshiek County decidedthat increased control of the landfill was needed and the landfill was purchased from Nishna.
Since that time, Winneshiek County has leased the landfill to the Winneshiek County AreaSolid Waste Agency for operating purposes.
The Winneshiek County Sanitary Landfill is a regional landfill serving the counties ofWinneshiek, Howard, and Clayton, the municipality of Postville, and Fillmore County inMinnesota. The population served by the Winneshiek County Sanitary Landfill is approxi-mately 63,000.
The tipping fee at the landfill is $56.00 per ton. All items accepted at the landfill, with theexception of appliances and brown goods, are charged by the ton. Appliances are charged$18.00 each with the exception of commercial appliances, which are charged at $1.50 percubic foot of total unit size. Brown goods, which include TV's and computer monitors, arecharged $18.00 each. Fluorescent light ballasts are charged $5.00 each. There is no minimumcharge at the landfill. The tipping fee at the landfill is the sole means of revenue collected.
It is estimated that the remaining life of this landfill is 14 years (2019). When the landfill isclosed the Winneshiek County Area Solid Waste Agency is required to monitor and maintainthe site for the following 30 years. The items that will be monitored include methane gasproduction, settlement, groundwater, storm water runoff, leachate, fencing, vegetation,building maintenance, and erosion. Closure and post-closure costs at this site are included inthe tipping fee that the current landfill customers are paying. Closure and post-closure costsat this site are currently estimated at $5,600,000.
The property owned by the county for this site is approximately 200 acres. The landfill footprint, the area that actually contains sold waste, is approximately 83 acres.
The Department of Natural Resources regulates landfills through the solid waste program.
Landfills are tracked from the initial site selection (in this case by Nishna in 1974), throughapproval of the engineer's site plans, construction of base works, day-to-day operations, finalclosure, and the 30 year post-closure monitoring and maintenance.
The DNR's Solid Waste Section gives initial site approval, approves plans, and monitorsreports that the landfill operators and responsible officials are required to submit. The reportsinclude water monitoring, gas monitoring, and engineer inspections.
The DNR's Field Office located in Manchester inspects the site on a periodic basis forcompliance with the solid waste regulations and to offer operator assistance. The Field Officealso maintains a working relationship with the landfill personnel so they are aware thatassistance from the DNR is available. The Field Office also works closely with the SolidWaste Section to insure that any concerns noted in any of the reports are properly addressed.
Bob Libra, State Geologist, Iowa DNR-Geological Survey
Groundwater monitoring is required at all Municipal Solid Waste Landfills. Monitoring wellsare placed and designed based on the "hydrogeologic investigation" that was done for eachlandfill. A range of parameters are measured depending upon well position and site history.
In 2004, a review of annual monitoring reports from landfills was conducted by the DNR-SolidWaste and Geological Survey staff. At that time, there were 14 monitoring wells in use at theWinneshiek landfill. Wells monitor both the "top of the water table" within the unconsolidateddeposits, and groundwater from the underlying bedrock. Two locations on Trout River are
also monitored, as the stream passes close to the landfill and loses water into the GalenaLimestone downstream to the north. While some monitoring wells have detected indicationsof landfill leachate in the shallow geologic materials, concentrations have not been signifi-cantly above background, and no upward trends were visually identified in the monitoringdata. The review included a recommendation for better monitoring of the deeper zones, giventhe relatively vulnerable nature of the underlying aquifers. Stream sampling has shown minorcontamination in Trout River. The landfill operates a leachate control/recirculation systemwhich is likely helping to limit leachate movement.
A Trout Stream at a Landfill
Bill Kalishek, Biologist, Iowa DNR-Fisheries
Trout River is a small coldwater stream that originates 2 miles south of the Winneshiek Countylandfill. As the stream flows north toward its confluence with the Upper Iowa River it isadjacent to the east edge of the landfill site. Downstream of the landfill Trout River is a losingstream and goes completely dry in one segment during most summers. This stream has beenstocked with four-inch fingerling brook trout yearly since 2000. Brook trout are the trout thatare native to Iowa and the trout species that is the most intolerant of warm water temperaturesand pollution. These trout have survived and flourished in the section of Trout River on thelandfill property. Recent fishery surveys have shown good numbers of brook trout presentwith fish up to 14 inches in length. In the case of the Winneshiek County Landfill, a managedbrook trout stream and a landfill are compatible uses for the same piece of property.
Figure 6-1. Geologic map of the Hecker Creek – Postville area.
Hecker Creek – Losing Streams
Hecker Creek is a tributary of the Yellow River. The creek heads near Postville and joinsthe Yellow about 5 miles north, just a short distance downstream from this stop. Theuppermost part of the watershed is underlain by bedrock of the relatively slowly permeableMaquoketa Formation, and a relatively thick cover of glacial deposits. As the stream flowsnorth, its valley cuts into the underlying karstic Galena Limestone. Where the stream runsover the fractured Galena bedrock, it "loses water" into the rock. During relatively dryconditions, the entire flow disappears into the rock. At this stop we will visit one of the placesthe stream typically sinks. Figure 6-1 shows the Hecker Creek – Postville area.
Losing Streams in Iowa
Bob Libra, State Geologist, Iowa DNR-Geological Survey
Losing streams like Hecker Creek are not uncommon in northeast Iowa and other parts ofthe state that are underlain by shallow permeable bedrock. Some streams lose water into theirunderlying sand and gravel deposits, even when no shallow rock or karst is involved. Losingstreams are complex to characterize, as the losing aspect may vary seasonally, and thelocations where water goes into the ground often changes through the year with flowconditions. Efforts to map losing stream reaches, sinkholes, and springs are underway innortheast Iowa, including detailed geologic mapping to further our ability to predict wheresuch features are most likely to occur.
The Yellow River in this area provides a larger example of a losing stream. Like HeckerCreek, the Yellow River heads on the slowly permeable Maquoketa Formation, and as itsvalley cuts into the karstic Galena Limestone, the river loses water into the rock. In the drierparts of most years, the Yellow River has no flow as it crosses the Galena Limestone (seeFigure 3), although it is fed by an 80-square-mile watershed. Further downstream, the valleycuts into the Decorah Shale "floor" below the Galena. Where this occurs, numerous springsdischarge groundwater into the Yellow River, and its flow from that point on downstream istypically perennial.
Losing streams are defined by Iowa Code:
"Losing streams" means streams which lose 30 percent or more of their flow during theseven-day, ten-year low stream flow periods to cracks and crevices of rock formations,sand and gravel deposits, or sinkholes in the streambed.
An additional part of the Code addresses losing streams this way:
The Escherichia coli (E. coli) content of water which enters a sinkhole or losing streamsegment, regardless of the water body's designated use, shall not exceed a GeometricMean value of 126 organisms/100 ml or a sample maximum value of 235 organisms/
100 ml. No new wastewater discharges will be allowed on watercourses which directlyor indirectly enter sinkholes or losing stream segments.
Iowa streams, whether losing or not, commonly exceed these bacteria levels. At present, newdischarges to losing streams are not allowed, regardless of the level of treatment.
Streams that lose water to fractured rocks and sinkholes are typically considered greaterenvironmental and public health threats than those that lose water to sand and gravel aquifers,in that the lost surface drainage moves much faster and farther in fractured rock, and canappear in hard-to-predict places. The fractured rock situations also offers little or no filtrationof contaminants. Testing in the Hecker Creek area provides an example of the complexityof karst systems.
Dye traces in the Hecker Creek area
Paul Berland, Regional Watershed Coordinator, Northeast Iowa RC&D
Northeast Iowa RC&D, through a grant from the Altria Group, conducted a series of dyetraces along the Yellow River north of Postville during the summer of 2005, to gain anunderstanding of the dynamic surface water-groundwater interactions and travel paths in thispart of the watershed. Northeast Iowa RC&D contracted Dr. Calvin Alexander, Professorof Geology at the University of Minnesota, to assist with the dye traces and analysis of theresults. In order to map the watershed, three different color dyes were input into one of threedistinct locations: 1) above this stream sink in Hecker Creek; 2) in the Yellow River upstreamof where Hecker meets the Yellow River, and 3) into a sinkhole located in section 33 ofLudlow Township in Allamakee County, on the north side of the Yellow River (see Figure6-2).
Direct water sampling and activated charcoal packets were used to determine which of thedyes were present in various streams, drilled wells, and springs following dye injection.
Results of the study showed a connection between the three source waters and two differentsprings (see Figure 6-2). These are shown on a map in this section. Dye that went into thesinkhole in Ludlow Township resurged at Livingood Spring approximately 14 hours after inputand dye from Hecker Creek resurged at the Stonehouse Springs approximately 19 hours afterinput. A portion of the dye poured into the Yellow River sank underground and also resurgedat Stonehouse Springs. As evidenced by the study, surface water in karst landscapes candisappear underground through sinkholes and stream sinks, and readily mix with groundwateraquifers before reappearing from springs miles away. The dynamic surface to groundwaterinteractions in karst areas makes karst aquifers highly susceptible to contamination.
Water Quality Considerations
Rick Langel, Geologist, Iowa DNR-Geological Survey-Water Monitoring
Mike Wade, Environmental Specialist, Iowa DNR-Manchester Field Office
Hecker Creek receives wastewater discharged from the Postville/AgriProcessors treatmentplant, along with nonpoint source runoff from its watershed. Discharges from the plant occurduring discrete time periods. During dry conditions, Hecker Creek has little or no natural flowfrom the watershed. If the Postville plant discharges under such conditions, the water in thecreek is essentially all wastewater. During wetter periods, discharges from the plant mix with
Yellow River Watershed dye tracing results.
runoff from the watershed, and the resulting water quality is a blend of wastewater and runofffrom nonpoint sources. This range of conditions causes quite variable water quality in thecreek. After we have looked at more of the Yellow River watershed, we will discuss theresults of water quality monitoring at a number of its "subwatersheds," including HeckerCreek, to examine how point and nonpoint sources of various contaminants impact streamquality. In general, monthly monitoring since 2004 shows that Hecker Creek stands out interms of total phosphorus and nitrogen concentrations, relative to other Yellow Riversubwatersheds. It is also clearly higher in its chloride concentrations, which relates to the saltused by AgriProcessors in the kosher process. Concentrations of the indicator bacteria E. coliare higher in Hecker Creek than most, but not all, of the other subwatersheds. Improvementsin some measures of water quality are expected as the new Postville-Agriprocessorstreatment system comes online.
Postville Industrial Wastewater Treatment Plant –
Wastewater and Water Quality
Postville straddles the drainage divide between the Yellow and Turkey rivers. We are at thehighest elevation we will reach on the field trip. This, in combination with the regional dip, orslope, of the rock units, means we are at the "stratigraphically" highest point on the trip as well.
Postville is underlain by 40 to 100 feet of unconsolidated glacial materials which rest on theMaquoketa Formation. The karst-forming Galena Limestone is nowhere to be seen, and in factlies about 200 feet below us. Between Postville and the Yellow River (by our last stop), HeckerCreek cuts downward towards the upward-sloping Galena Limestone (Figure 6-1). Where thetwo meet, the creek begins to lose water.
Wastewater Discharge and the Postville Plant
Joe Sanfilippo, Supervisor, Iowa DNR-Manchester Field Office
Iowa has a little over 1500 facilities covered under individual "National Pollutant DischargeElimination System" (NPDES) permits. Of those about 800 are municipal facilities, 365 areindustrial facilities, 280 are semi-public facilities (such as mobile home parks), and there areabout 80 other miscellaneous facilities with permits (water treatment plants, land applicationfacilities, and industrial stormwater). In addition, there are three stormwater general permitsthat cover a total of more than 6000 active sites, and one general permit for over 400 rockand sand-and-gravel mining operations. At this stop we will visit one of the newer wastewaterplants in the state.
The Postville Industrial Wastewater Treatment Plant was constructed in 2005 to serve thewastewater treatment needs of a meat packing plant located adjacent to the treatment plant.
The new mechanical plant replaces an outdated and inadequate 4-cell lagoon treatmentsystem. The new plant was built at a total project cost of $10,800,000. AgriProcessors, themeat packing plant, has invested $4,200,000 in funding for the project. The other $6,600,000was funded through the City of Postville by loans and grants. The new plant was designedby Bolton & Menk of Ames, Iowa. Greg Sindt served as chief engineer.
The plant is designed to receive raw wastewater at a flow of 1,024,000 gal/day, with a CBODconcentration of 2,166 mg/l, and a CBOD mass load of 18,500 lbs/day. The plant must alsomeet the E. coli limit of 400 cfu/100 ml because the discharge from the plant is to a streamwith a losing segment. A losing segment indicates that significant stream flow is lost togroundwater. The plant will process the wastewater to meet permit limits of 30 mg/L CBODconcentration and 218 lbs/day CBOD mass. Treated water will be discharged to HeckerCreek which is a tributary to the Yellow River. AgriProcessors is a kosher meat processorwhich results in a slightly different wastewater load coming to the wastewater plant ascompared to the type of flow that would be seen from a similar, but non-kosher plant.
Basically, salt is used in the process which results in a high total dissolved solids and chlorideconcentration for the plant to treat.
The Department of Natural Resources regulates this facility through the National PollutionDischarge Elimination System (NPDES) permitting and inspection process. Plans for theplant, beginning with site location separation distances were submitted to the department andseparation distances were verified in the field. The final plans were reviewed and approvedby DNR engineers prior to construction. The plant will be monitored by AgriProcessors, whowill operate the plant and submit periodic reports to the department. The plant will also bemonitored by the DNR's Field Office in Manchester which will conduct periodic inspectionsof the plant, monitor the receiving streams (Hecker Creek and Yellow River) and respondto concerns from the public.
Glenwood Cave – Caves In Iowa
Mike Bounk, Geologist, Iowa DNR-Geological Survey
Bob Libra, State Geologist, Iowa DNR-Geological Survey
Glenwood Cave developed near the base of the Galena Limestone, about three milesnorthwest of the Winneshiek landfill. The mapped extent of the cave is shown in Figure 8-1.
The cave has been known at least since the late 1890s, when Professor H. W. Shiel, of LutherCollege, reportedly explored the cave and described its length at 2,400 feet with a stream"navigable" for 1,400 feet. The cave was apparently in "business" during the summers from1931-1935. Tours were offered by boat and cost 25 cents per person. The boats, which helda guide and two passengers, were poled by the guide. Illumination was by flashlight. SpookCave, east of Monona in Clayton County, is still in the underground boat-ride business.
During wet weather, the amount of groundwater discharging from the cave was enough tomake former residents of the area build a bridge over the discharge channel. During dryweather, the cave entrance leads downward about 10 feet to the water level. This wetpassage can be followed for about 1600 feet to a T intersection with a stream that flows fromleft to right. The cave "sumps" (is completely water-filled) about 30 feet to the right of the"T." It is believed to resurge at a spring located in the next valley to the north, on the westside of the road. To the left of the T, the passage continues for about 1100 feet, where thestream comes out of a narrow, impassable slot. A short distance before this, there is a"flowstone" climb to an upper level. Total passage length for this cave is about 1 mile. Thismakes it one of Iowa's longer mapped caves. However, it pales in comparison to ColdwaterCave, in northern Winneshiek County where over 16 miles of passage have been mapped.
Caves – particularly those with streams and those that are completely water-filled – areimportant parts of the karst groundwater system. They act as drains for the carbonateaquifers, efficiently transmitting water to spring outlets, much as tile lines drain the soil belowan agricultural field and deliver water to the tile outlet. Caves and smaller conduits can havesignificant influence on groundwater over large areas. They are fed by "tributaries" much likea surface stream, only the tributaries to caves are in all three dimensions.
Figure 8-1. Mapped extent
(in red) of Glenwood Cave.
Figure 9-1. Color infrared photo of the Enyart Farm showing sinkholes.
Enyart Farm – AFOs in Karst Part 1
The Enyart farm is located within the outcrop belt of the Galena Limestone, just north of theYellow River, and just to the south of Ludlow Township (Figure 9-1). Ludlow Township hasthe distinction for having the most mapped sinkholes of any township in Iowa: the county soilsurvey shows more than 1000 sinkholes in the 36-square-miles of the township, or about onemapped sinkhole every 20 acres. The sinkholes here aren't all mapped; in places the soilsurvey stopped trying to map individual sinkholes and created a soil mapping unit that isdescribed as containing "sinkholes too numerous to map."
Senate File 2293, the latest major livestock bill, banned confinement structures within 1000feet of "known" sinkholes. DNR uses soil-survey mapped sinkholes as "known" sinkholes.
Figure 9-2 shows these for Allamakee County. Much of the soil mapping was carried out 20or more years ago. DNR's Geological Survey, the Northeast Iowa RC&D, and other partnersare mapping sinkholes in the area to improve and update our knowledge of their locations andcharacteristics.
In Ludlow Township and adjacent areas, over 75% of the land is within 1000 feet of knownsinkholes, as shown by Figure 9-3. At the Enyart Farm, sinkholes are present within 200 feetof the farm's AFO structures. Fortunately, the dairy operation does not drain to the nearbysinkholes.
Enyart Farm Dairy Operation
LuAnn Rolling, NRCS District Conservationist
Brian Enyart, Farm Operator
Chad Kehrli, Environmental Specialist, Iowa DNR-Manchester Field Office
Brian Enyart is a beginning farmer. He purchased the land, facilities, and livestock from hisfather. The operation includes a 90-head dairy herd. To improve manure handling, Brianadded an 8-foot deep, 90-foot circular tank. The tank gives him about 5 months of manurestorage, and eliminates the need for daily scraping, hauling, and applying of manure. As thetank is within 1000 feet of known sinkholes, the operation needed a variance from DNR toconstruct the tank. The variance was granted based on the fact the tank and barn areas don'tdrain to the nearby sinkholes, and that the addition of the structure was likely to improveenvironmental protection (about 12 variances for sinkhole or stream separation distanceshave been granted in northeast Iowa). However, the presence of nearby sinks and shallowGalena Limestone places the operation in "karst terrain" and therefore the tank was built tothe upgraded concrete standards put in place by DNR at the direction of SF 2293. The totalcost of the tank was about $47,400, or a little over $500/animal. NRCS staff oversawconstruction of the tank, and Brian received 50% cost share from the Environmental QualityIncentive Program (EQIP), plus an additional 25% as he qualified as a ‘beginning farmer."As a requirement of receiving USDA assistance the NRCS wrote a "ComprehensiveNutrient Management Plan," which the producer is required to follow. Part of this planincluded DNR rules requiring setback distances for manure application around sinkholes.
Figure 9-2. Soil Survey sinkholes in Allamakee County.
Figure 9-3. Over 75% of the land in Ludlow Township is within 1000 feet of known sinkholes.
Forestry Planting – Alternative Land Use
From Stop 9 we have traveled about 5 miles due east, downstream through the Yellow RiverValley. Stop 10 overlooks the valley, which has cut through the Galena Limestone and intothe underlying St. Peter Sandstone. As this occurs, groundwater from seeps and springs inthe Galena flows into the Yellow River. In this reach, it is again a "typical" gaining stream.
Here, uphill from the valley, the Galena rocks are the uppermost bedrock, and sinkholes andshallow limestone characterize the landscape.
Bruce Blair, District Forester, Iowa DNR-Forestry
The property we are visiting is owned by Leigh Keehner, of Farmersburg, Iowa. The sitehighlights a 75.2 acre direct seeding under a CRP/CP3A tree planting contract. The site wasplanted in the fall of 1996. A total of 1125 bushels of walnut (15 bushels/acre) + 75 bushelsof white oak (1 bushel/acre) + 75 bushels of green ash (1 bushel/acre) + 35 bushels of buroak (1/2 bushel/acre) were sewn. First, the site was disked following corn harvest. The seedwas broadcast using a fertilizer cart. The site was disked a second time to incorporate theseed. In the spring, Pendulum® 3.3 EC herbicide was applied at a rate of 3 quarts/acre. Asecond application of herbicide was applied in the fall of 1997. No other major managementhas been done to the site since then. The walnut, ash and bur oak seed all germinated well.
Typically, we would have applied red oak seed instead of bur oak and white oak, but therewas no red oak seed crop that year.
The wood products industry in Northeast Iowa is booming. The region's climate and greatsoils combine to produce some of the highest quality fine hardwoods in the world. Buyerstravel from all over to Northeast Iowa because we are viewed as growing some of the bestquality black walnut anywhere. In a recent timber harvest in Delaware County, a 2.5 acrestand of red oak, white oak and black walnut sold for $29,200. The 140-year-old trees werequite large, but were otherwise of typical quality for the area. The stand went virtuallyunmanaged from the time squirrels planted the seeds. The stand averaged $83.43 of net returnper acre per year with very small input costs including no property taxes.
The water quality benefits from timber production are obvious when compared with row cropproduction. Storm runoff is minimal with most of the rain being intercepted by the forestcanopy and absorbed in the soil. Pollution from pesticides and nutrients is a tiny fraction ofthat from row crop production. Woodlands also provide clean air, wildlife habitat, carbonstorage and recreation. Timber production in Northeast Iowa is a terrific conservationalternative. Policy makers and natural resource agencies should promote timber productionon our most highly erodible farm ground.
Pasture based dairies
James Ranum, Grassland Conservationist, NRCS
A pasture based dairy will have around one acre of intensively managed pasture per cow.
They may have another half acre of hay where they take one or two cuttings, then graze. Theymay purchase their stored feed, creating a market for other producers. These well managedpastures will be a dense sward which practically eliminates soil erosion and greatly reducessurface runoff. On a 10% slope, a 3-inch rain in 90 minutes will only have 10% runoff vs. 50%to 60% for cropland or overgrazed pastures. The reduced runoff decreases the chance ofnutrients and pesticides reaching sinkholes. Another water quality advantage is the reducedamount of fertilizers and pesticides applied to the land. A 100-cow dairy would have 100 acresof pasture receiving 0 to 100 lbs/acre of nitrogen and minimal phosphorus compared to rowcrop that would be heavily fertilized. Pesticides are only spot applied as needed, as opposedto broadcast applications for cropland. Another advantage can be the reduced amount ofmanure storage needed. Seasonal systems can have the cows on pasture from seven totwelve months spreading their own manure. Cropland can be converted to long-term pasturefor less than $100 per acre making this system the most cost effective method of erosioncontrol.
The local community receives considerable economic benefits from dairies, and newoperations should be a priority. Grass-based systems are a viable entry avenue for beginningfarmers. 200 acres could support a 100-cow dairy. Low costs and labor efficiency are thekeys to success. An efficient milking parlor is essential and should be considered as a costshareable practice in the same manner as a manure storage structure.
Thompson-Reisinger Farm – AFOs in Karst Part 2
The Thompson-Reisinger Farm is located in the outcrop belt of the Prairie du Chien dolomite.
These carbonate rocks form an important statewide aquifer. Wells as far southwest as theDes Moines area are drilled into the Prairie du Chien and the underlying Jordan Sandstone,where these rocks lie more than 1500 feet below the surface. The Prairie du Chien typicallyexhibits solutionally enlarged openings, but rarely sinkholes. As the geologic map in yourguidebook shows (Figure 3), the number of Prairie du Chien sinkholes mapped by the countysoil survey are miniscule compared to those mapped on the Galena Limestone. Howeversubsurface voids do occur in the Prairie du Chien , even though there are no sinkholes to helpindicate their presence. At the Thompson-Reisinger farm, unanticipated voids were found tobe present and affected the manure upgrades the operators were planning.
Thompson-Reisinger Farm Dairy Operations
LuAnn Rolling, NRCS District Conservationist
Pat Reisinger/Bob Thompson, Farm Operators
Pat Reisinger is a beginning farmer. He purchased the facilities and livestock from his father-in-law, Bob Thompson. The farm includes a 160-head dairy. The operators were workingwith NRCS to add a manure storage tank. They added a 12-foot-deep, 120-foot circular tank.
The tank gives the operation about 6 months of manure storage and eliminates the need fordaily scraping, hauling, and applying of manure. As there are no "known" soil survey sinkholeswithin 1000 feet, a variance from rule was not needed at this site. However, the presence ofshallow fractured Prairie du Chien rocks did place the site in karst and required the tank tobe built to the upgraded concrete standards put in place by DNR at the direction of SF 2293.
The total cost of the tank was $82,000, or about $500/animal. NRCS staff oversawconstruction of the tank and Pat received 50% cost share from the Environmental QualityIncentive Program (EQIP). As a requirement of receiving USDA assistance the NRCSwrote a "Comprehensive Nutrient Management Plan," which the producer is required tofollow.
During excavation for the tank a small cave system was discovered below the planned tanklocation, raising questions as to whether the tank could be built there. The caves, which canbe entered by crawling, were investigated by staff from the DNR's Geological Survey. Afterdiscussions with NRCS Engineers, DNR geologists and field office staff, and others, thedecision was made to move the tank uphill, where the potential for a thicker "roof" over thevoids would be greatest; roof in this case being both thicker rock and a thicker soil zone overthat rock. In addition the design was modified such that less excavation would be needed,again adding to the separation between the tank and any voids. It was felt that this approach,adding a greater cover of rock and soil over any voids, in combination with the structuralstability provided by the upgraded concrete standards, would be sufficient to protect theintegrity of the tank, the environment, and the investment made by the operators and EQIP.
Figure 12-1. Color infrared photo of the Rossville area showing sinkholes.
Rossville County Park – Stepping Inside a Sinkhole
Rossville County Park is located on the drainage divide between the Yellow River to the southand Paint Creek to the north. State Highway 76 follows the divide southeast to the MississippiRiver, a distance of roughly 10 miles. The valleys of Paint Creek and the Yellow River arecut through the Galena Limestone and into the St. Peter Sandstone and older rocks. But onthe divide, Galena Limestone is present much of the way to the Mississippi River, andsinkholes are very common in the Rossville area (see Figure 12-1). We will view and entera prominent sinkhole in the wooded part of the park, and see several depressions in the groundwhere sinkholes appear to be forming…or re-forming.
Bob Libra, State Geologist, Iowa DNR-Geological Survey
Percolating soil water is typically acidic and therefore can dissolve carbonate rocks such aslimestone. When near surface fractures and cracks are dissolved into larger voids, theoverlying glacial soils may no longer have the strength to bridge the void, and will slowly beginto slump downward. The process of dissolving out voids takes thousands to tens of thousandsof years. The failure of surface soils over the void is a much shorter process. It can occurover months to years, or it can occur instantaneously. Figure 12-2 is a schematic depictionof sinkhole formation. Saturated glacial soils will collapse into voids more readily than drysoils. They can flow and ooze into relatively small openings. For this reason, seepage fromearthen structures such as lagoons and farm ponds may accelerate collapse, as the seepagekeeps the underlying soils permanently saturated. This was the unfortunate case of theGarnavillo sewage lagoon in Clayton County in the early 1980s.
The Garnavillo lagoon system was built as a passive three-cell system, a design easy for thesmall community to maintain and operate. The cell shown was built into a hillside, with thefloor of the lagoon cut to within 5 feet of the Galena Limestone. As the lagoon system wasapproaching completion, stormwater was directed into this cell to test the seal of the liner,filling the cell to roughly a 1-2 foot depth. This occurred on a Friday afternoon. By Mondaymorning, a sinkhole had formed and the lagoon was dry (Figures 12-3 and 12-4). Over thecoming months a line of small depressions formed in the cell. Ultimately, this cell and a secondwere abandoned. The third cell, which overlies a thicker cover of glacial materials, wasconverted to an aerated system. This was a less simple design than the city had planned on,but it was a retrofit that would work.
In the more typical setting in the countryside, when a sinkhole forms, it becomes the new lowspot on the ground. Runoff will flow downhill into the sinkhole, and typically cause headwarderosion and the establishment of a drainage way leading to the sink. Eventually the sinkholemay form its own watershed. Other sinkholes form in streams beds and are referred to morecommonly as stream sinks or just as a losing stream point. These sinkholes come with theirown watershed.
Figure 12-2. Diagram showing steps in sinkhole formation.
Since sinkholes take surface drainage, they receive inputs of sediment as well. Often, theywill become "plugged" with sediment, and have no obvious opening. However, since they willcontinue to receive drainage, they will often plug and unplug repeatedly. This can happen ontimescales of months, years, or decades. Sinkholes have been known to "form" and exposedecades-old farm equipment that was dumped in a former sinkhole, at that location, in the past.
Along with sediment, sinkholes may receive runoff containing relatively high levels ofherbicides, phosphorus, bacteria, ammonia nitrogen, and organic matter. This water isdelivered into the groundwater system with little or no filtration, and may travel quicklythrough the fractured and karsted rocks. The water may impact wells or recharge thecoldwater streams found in the valleys below.
As suggested above, sinkholes are far too convenient locations for waste disposal. Trash, oldequipment, white goods, cars, and pesticide cans have been disposed of in sinkholes in thepast. While this practice is no longer as common as it used to be, some dumping still occurs.
The Groundwater Protection Act of 1987 provided funds for a number of sinkhole cleanups.
As you can imagine, removing large quantities of trash and old equipment, mixed withsediment and rock, is not an easy or inexpensive task.
Figure 12-3. City of Garnavillo lagoon after sinkhole failure.
Figure 12-4. Close-up of sinkhole at city of Garnavillo lagoon.
Figure 13-1. Monitoring locations and subwatersheds in the Yellow River Basin.
Lower Yellow River – Watersheds and Water Quality
We are now most of the way down the Yellow River watershed. The Mississippi River isabout 7 miles east as the crow flies. The Yellow River headwaters are 25 miles to the west,and about 500 feet higher in elevation. Here the valley has cut through the Galena Limestoneand St. Peter Sandstone, and into the Prairie du Chien Dolomite. Groundwater from springsand seeps continues to discharge to the river, increasing its flow.
Paul Berland, Regional Watershed Coordinator, Northeast Iowa RC&D
The Yellow River Watershed (YRW) encompasses approximately 154,500 acres inAllamakee, Clayton and Winneshiek counties in extreme Northeast Iowa. The YRWcontains 59.8 miles of surface water designated as High Quality Resource waters, 27.9 milesdesignated for Coldwater Aquatic Life (BCW), and 21.9 miles designated for Primary BodyContact. The YRW also encompasses Effigy Mounds National Monument, portions of theYellow River State Forest, and drains into the Upper Mississippi National Wildlife Refuge.
The Yellow River itself is the largest coldwater trout stream in Iowa. Despite its beauty andimportance, several segments in the YRW are listed as impaired due to low aquatic life orelevated levels of bacteria.
In response to these impairments, the YRW Project at Northeast Iowa RC&D is leadingwatershed protection efforts in the YRW. The YRW Project Alliance is a collaboration offederal, state and local agencies, organizations and individuals dedicated to protecting andimproving water quality and watershed health. At the forefront of the protection efforts isweekly water monitoring of 12 sites throughout the watershed, including 9 tributaries of theYellow River and 3 sites on the Yellow River itself. The monitoring is funded through the IowaDNR and conducted by the Allamakee County Soil and Water Conservation District(SWCD), the Winneshiek County SWCD and the Northeast Iowa RC&D staff. Waterquality data obtained through the monitoring effort are used to identify impairments and tomonitor water quality improvements. Once priority subwatersheds are identified, GeographicInformation Systems (GIS) technology is being utilized to target particular land areas withinthe subwatersheds for specific watershed protection programs to address impairmentsources. The local Natural Resources Conservation Service (NRCS), Farm Service Agency(FSA), and SWCD offices, as well as the Iowa DNR are assisting with the implementationof the watershed protection programs. Other partners working with the YRW Project toimprove water quality in the YRW include; Iowa Department of Agriculture and LandStewardship, U.S. Fish and Wildlife Service, National Park Service, U.S. Forest Service,U.S. Geological Survey, Pheasants Forever, Northeast Iowa Citizens for Clean Water, U.S.
Environmental Protection Agency, Altria Group and the McKnight Foundation.
Water Quality Monitoring on the Yellow River Watershed
Rick Langel, Geologist, Iowa DNR-Geological Survey, Water Monitoring
In 2002, segments of the Yellow River were listed on the State of Iowa's 303(d) list ofimpaired waters. A cooperative project involving the U.S. National Park Service, U.S.
Department of Agriculture, Iowa Department of Natural Resources, University of IowaHygienic Lab (UHL), U.S. Geological Survey-Water Resources Division, and the AllamakeeCounty Soil & Water Conservation District was started to provide baseline water quality datafor the Yellow River watershed. Twelve sample locations in the Yellow River watershedwere selected for water-quality monitoring and have been sampled since May 20, 2004.
Figure 13-1 shows the monitored subwatersheds. Summarized below are monitoring resultsfor nitrate-nitrogen, total phosphate-P, the bacteria E. coli, and chloride. Data from othernortheast Iowa streams for that time period are also shown for comparison.
Nitrate+nitrite-N is an inorganic form of nitrogen in Iowa's streams and groundwater.
Nitrogen is a necessary nutrient for plant growth. Excess nitrogen in surface waters,however, can contribute to nutrient enrichment, increasing aquatic plant growth and changingthe types of plants and animals that live in a stream. The maximum allowable level of nitrate-N in drinking water is 10 mg/L. Sources of nitrogen include cultivated soils, human and animalwastes, decomposing plants, and fertilizers. Most nitrate is "leached" from soils by infiltratingsoil waters. Figure 13-2 shows nitrate+nitrite-N concentrations for the Yellow River area.
Nitrate+nitrite-N concentrations ranged from <0.05 mg/L to 17 mg/L in the Yellow Riverwatershed. Many streams in the watershed had higher nitrate+nitrite–N concentrations in thelate spring/early summer, a trend that is similar to streams statewide. As summer progressed,nitrate+nitrite-N concentrations declined and were often lowest during late summer andwinter periods. In general, watersheds with higher percentages of row crops had highermedian nitrate-N concentrations. Median concentrations were around 7 mg/L for mosttributaries, but were less than 5 mg/L for the Lower Yellow River.
Total phosphate-P is a measure of all dissolved and particulate forms of phosphate in water.
Phosphorus is a necessary nutrient for plant growth and generally is limiting in the freshwaterenvironment. Too much phosphorus in surface waters, however, can contribute to nutrientenrichment, increasing aquatic plant growth, and changing the types of plants and animals thatlive in a stream. Sources of phosphorus include certain soils and bedrock, human and animalwastes, decomposing plants, and runoff from fertilized lawns and cropland. Figure 13-3shows total phosphate-P for the watershed sites.
Total phosphate-P concentrations ranged from <0.02 mg/L to 5.1 mg/L in the Yellow Riverwatershed. Median concentrations clustered around 0.1 mg/L. With the exception of theHecker Creek site, the total phosphate-P concentrations throughout the watershed weresimilar to those reported from other northeast Iowa streams. In general, watersheds withhigher percentages of row crops had higher median total phosphate-P concentrations.
Nitrate+nitrite as N (mg/L)
Figure 13-2. Nitrate+nitrite-N concentrations for theYellow River and northeast Iowa streams.
Total Phosphate as P (mg/L)
Figure 13-3. Total Phosphate-P concentrations for the Yellow River and northeast Iowa streams.
However, several high total phosphate-P results at the Hecker Creek and Upper Yellow siteswere associated with discharges from the Postville-Agri Processors industrial lagoon.
E. coli Bacteria
Escherichia coli (E. coli) bacteria are a type of coliform bacteria present in the gastrointes-tinal tract of warm-blooded animals. Escherichia coli is called an "indicator bacteria,"meaning they do not cause illness, but their presence suggests that disease-causing organisms(pathogens) may be present. As the number of indicator bacteria rises in water, so does thelikelihood that pathogens are present. The most frequent sources of pathogens are sewageoverflows, malfunctioning septic systems, animal waste, polluted storm water runoff, andboating wastes. The presence of E. coli bacteria suggests that a pathway exists for arelatively fresh source of human or animal waste to enter the stream. Figure 13-4 shows E.
coli concentrations for the watershed sites.
The E. coli concentrations ranged from <10 to 360,000 colony forming units (CFU)/100 mL.
If all the streams in the watershed were classified as "swimmable," all the streams wouldexceed the State of Iowa's one-time maximum E. coli standard (235 CFU/100 mL). Manyof the monitored sites in the Yellow had median concentrations exceeding this level. High E.
coli results at the North Fork and Yellow River Subwatershed sites occurred on the days thatalso had high rainfall and high ammonia-N concentrations, which may indicate that theseproblems were caused by manure entering the streams. These watersheds, and HeckerCreek, had the highest median E. coli levels.
Chloride is a component of salt, and can be used as an indicator of human or animal wasteinputs to a stream. Potential sources of chloride to a stream include direct input from livestock,septic system inputs, and/or discharge from municipal and industrial wastewater facilities.
During winter months, elevated chloride levels in streams may occur as a result of road saltrunoff to nearby streams. Figure 13-5 shows chloride concentrations for the monitored sites.
Chloride ranged from 4.9 to 1,900 mg/L in the Yellow River watershed. Chloride data fromother water monitoring stations showed median chloride levels typically below 25 mg/L acrossnortheast Iowa. Two sites in the Yellow River watershed, Hecker Creek and the UpperYellow River, had chloride values that routinely exceeded 25 mg/L. For both sites, highchloride values were associated with discharges from the Postville-Agri Processors industriallagoon.
In summary, nonpoint and point sources of contamination both deliver contamination to theYellow River. The large industrial point source impacting Hecker Creek has clear effects interms of total phosphate-P and chloride concentrations. Hecker Creek does not stand out ashigh in terms of its nitrate+nitrite-N concentrations. However, the wastewater dischargecontributes other forms of nitrogen to Hecker Creek, and the creek is high in terms of totalnitrogen levels. Median concentrations of the indicator bacteria E. coli are above the"swimmable" criteria for most of the monitored sites, indicating that widespread bacterialsources exist throughout the watershed.
E. coli (cfu/100 mL)
Figure 13-4. E. coli concentrations for the Yellow River and northeast Iowa streams. Dashed red
line shows Iowa's one-time maximum E. coli standard.
Figure 13-5. Chloride concentrations for the Yellow River and northeast Iowa streams.
Yellow River Fishery
Bill Kalishek, Fisheries Biologist, Iowa DNR Fisheries
The Yellow River is Iowa's largest coldwater trout stream. At this point the river has a 204-square-mile surface drainage that extends west almost to the towns of Ossian and Decorah.
Most Iowa trout streams have surface drainages that do not exceed 40 square miles. Inaddition to the large surface drainage there are 2953 documented sinkholes and 277 individualsprings that contribute to the Yellow River. Many of the sites that we have visited in the lasttwo days are within this watershed and contribute directly to the quality of the water at thislocation. The Yellow River is impacted by one industrial and two municipal waste treatmentplants, a myriad of private septic systems, and the nonpoint runoff from predominantlyagricultural landuse; the scope of the challenge to maintain suitable water quality for troutsurvival can seem huge.
The Yellow River drainage has nine major tributary streams. Four of these tributaries arecoldwater trout streams. Historically the majority of the main stem of the Yellow Riversupported a warmwater fishery dominated by smallmouth bass. But over the last two decadesover 25 miles of the Yellow River have water temperatures that have become cold enoughto support trout populations. Fish populations in the Yellow River are very diverse, consistingof 39 different species. The Yellow River trout populations are maintained by annual four-inch fingerling stockings of 50,000 rainbow trout and 50,000 brown trout. All of the stockedbrown trout fingerlings originate from adults captured in the wild; the rainbow trout areoffspring of domestic hatchery brood stock.
Effigy Mounds – Northeast Iowa and the Mississippi River
At Effigy Mounds, the Yellow River flows into the Mississippi River. The water carries thesediment, nutrients, and chemicals from nonpoint source runoff and infiltration, and point-source discharges, from its 240-square-mile watershed. The Mississippi and Yellow Rivervalleys are cut through the Prairie du Chien Dolomite and into the upper parts of the JordanSandstone. The Jordan-Prairie du Chien interval is typically called the Jordan Aquifer. Thiswidespread, productive aquifer supplies wells as far away as central Iowa, where it lies over1,500 feet below the surface. Only here in the northeast corner of the state are these rocksexposed at the surface.
Effigy Mounds owes its status as a National Monument primarily to its archeologicalresources, in particular the burial mounds constructed by the Eastern Woodland Indians.
While these archeological treasures are beyond the scope of our trip and guidebook, theirpresence here tells us that humans have lived along, fished in, and treasured the MississippiRiver for thousands of years.
The Driftless Area National Wildlife Refuge
Cathy Henry, U.S. Fish and Wildlife Service
The karst geology of the Paleozoic Plateau in Iowa, along with varying slope aspects, rockoutcrops and springs, creates many unique habitats. One of these habitats is algific talusslopes, also known as cold air slopes. Algific slopes are home to a host of state and federalthreatened and endangered species, as well as other endemic and rare species.
In the summer, air is drawn down through sinkholes, flows over frozen groundwater and exitsfrom vents onto certain slopes, usually north facing. These cold air vents are usually coveredby a loose talus (rock) layer. Temperature ranges from freezing to about 55 degreesFahrenheit throughout the summer. This air flow provides a climate similar to what wasprevalent in glacial eras and creates a habitat that a specific community of plants and animalsneed to survive. Some of the plants and animals are relicts from glacial eras. The plantcommunity contains species that normally grow much farther north.
Algific talus slopes are sensitive to disturbance and activities that might disrupt air flow, suchas the filling in of sinkholes. The Driftless Area National Wildlife Refuge was established in1989 to permanently protect habitat for the federally threatened Northern monkshood andendangered Iowa Pleistocene snail. The Refuge currently covers 781 acres in 9 separateunits. Additional acquisition throughout the four-state driftless area is planned.
Water Quality and Mississippi River Recreation
Scott Gritters, Fisheries Biologist, Iowa DNR Fisheries
Every inch of ground you have traversed for this trip drains into the Mississippi River. Everywaterway, tile, spring, sinkhole, pasture, gaining stream, losing stream, industrial complex,
cement road, septic, storm drain, toilet flush, forest, and row crop drains through here. ForIowans, the Mississippi River is where our association with the water quality stops. However,the issues you have been discussing ultimately impact our downstream neighbors all the wayto the Gulf of Mexico.
Iowans are blessed to have this mighty water source on our border. The Mississippi Riversupports a massive tourism industry and offers unequaled recreation opportunities. More than3 million people visit the Mississippi River each year making it the most visited refuge in thecountry. It is also a world-class fish and wildlife area harboring 306 species of birds and 119species of fish. Fishing, hunting and other river-based recreation along our border is BIGBUSINESS. As with any business, continued investments are needed to keep it vital. Ofparamount importance are investments in water quality improvements, discussed during thistrip.
The challenges that influence river health are complex and include invasive species,navigational impacts, habitat alteration, and island loss to name a few. However, the singlebiggest challenge we face as river managers is sedimentation. On average, Iowa tributarystreams deliver dump truck loads of sediment to the Mississippi River every few minutes. Thisclogs the lifeblood of the mighty river. Backwater areas vital to fish and wildlife productionare silting in at a rate of ½ to 1 inch per year, and over the past 60-plus years, the impoundmentbackwater depth has been reduced three to six feet. All backwaters have been degraded,limiting their ability to produce fish and wildlife, and many have already been completely lost.
Losing areas to sedimentation has ecological as well as financial implications. We are tryingto correct some problems with programs such as the Environmental Management Program.
To date, 16 large-scale ecosystem rehabilitation projects totaling nearly $37 million have beenimplemented or are on the verge of construction in Pools 9 through 11. These programs, plusa strong emphasis to keep Iowa's soil on Iowa's land is what is needed for the MississippiRiver's, and Iowa's financial and ecological health.
eld conference stops.
Generalized geologic map of northeast Iowa showing ﬁ
Iowa Department of Natural Resources
109 Trowbridge Hall
Iowa City, Iowa 52242-1319
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