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One creek for many uses
A change in the groundwater law
Casing a solution
Understanding what can't be seen
An old schoolhouse, just east of Viroqua in Vernon County, is the peaceful place Paul and Laurie Wallace call home. Cook Creek, a small trout stream, splashes and gurgles by just a stone's throw from the house. However, one day in 2004, something didn't seem quite right: It was too quiet. Oh, there was the normal din of the day given two children and an outspoken yet friendly group of coon hounds, but something was missing.
On closer inspection, the Wallaces realized Cook Creek had ceased flowing. They immediately called the Vernon County Land and Water Conservation Department. A staff member came out, took photos and reported the incident to a Wisconsin DNR warden. The warden came out, looked around, determined no fish had perished and no laws had been broken, even though the water in the stream was completely gone. Within a few weeks, the stream began to flow again as mysteriously as it had stopped.
The unusual occurrence was probably one of nature's oddities, they thought – until it happened again, and again.
It was as if the waterway operated like a bathtub and someone had just turned off the tap and pulled the plug; the bubbling, rushing stream became an uneven, rocky ravine dotted with puddles of water. DNR biologists responded rapidly to a call of concern late in the summer of 2005, when water levels and flow rates were dropping fast, trapping fish in isolated pools. The fish were captured and moved downstream to places where sufficient water still flowed deep and fast. The fishery was salvaged, but there was still no explaining why segments of the stream drained twice a year.
One creek for many uses
Cook Creek is a Class I trout stream that contains naturally reproducing schools of brook trout along with healthy populations of mottled sculpin and an abundance of aquatic insects including mayflies, stoneflies and caddisflies. The creek is a fed by a network of springs approximately a hundred yards upstream of the Wallace property. The stream flows in an easterly direction for nearly two miles before joining Maple Dale. These two waters both flow into a larger trout stream, Bishop Branch, which feeds into the web of waters forming the Kickapoo River.
The shallow upper end of Cook Creek serves as a spawning area and nursery for young brook trout. In the fall spawning season, adult brook trout seek out cold, oxygen-rich areas where groundwater seeps into the stream. The flowing springs bathe the fertilized eggs with fresh water throughout the winter while they grow. In spring, the young fish emerge from the gravelly streambed and swim freely, looking for food. As the young fish forage for insects and grow, they spend much of their time in the headwaters of Cook Creek adjacent to the Wallace home. As the fish approach adult size (approximately seven inches), they move downstream in search of larger prey.
Across the road and up the hill from the Wallace home lies the Mollett Quarry, owned by the Kraemer Company. Approximately twice a year, the companyquarry would pump water from a high-capacity well on the property to wash big piles of gravel crushed from its pits; the cleaned gravel is used for specific concrete mixes and road projects. The Wallaces had noticed that the quarry's well was in use each time the stream went dry.
"Whether it's with a pump and tanker or a high-capacity well, no one should be able to dry up a creek simply because they need water," Paul Wallace said. Even so, the quarry was operating within the limits of its well approval issued in 1994.
To look for clues that might explain any connection to the water loss in Cook Creek, investigators reviewed the construction report detailing the well depth and descriptions of each rock layer encountered when the high-capacity well was drilled. The report raised the possibility that the well penetrated two distinct aquifers separated by a layer of impermeable rock. DNR groundwater specialists surmised it was possible that when the well pump was operated to wash gravel at the surface, it pulled water from the upper aquifer, which likely also supplied water to Cook Creek.
The well had been drilled properly and had the required 60 feet of steel casing and cement grout. The casing and grout keep the well from caving in and prevent surface water and shallow groundwater from contaminating deeper aquifers. An inspection of the well confirmed it met safety measures and complied with the groundwater law in place at the time the well had been drilled in 1994.
A change in the groundwater law
Due to concern that a proposed water bottling plant in Adams County could dewater neighboring trout streams, the groundwater law was updated in 2003 to state require that high-capacity wells could not be sited closer than 1,200 feet from a trout stream. Permits for high-capacity wells that cannot not be located outside this groundwater protection area of 1,200 feet could still be issued if the Department of Natural Resources could propose an alternative well location or add specific conditions on well construction to lessen the environmental consequences. Although the Mollett Quarry well is only 350 feet from Cook Creek, it was grandfathered in under the previous regulations. Because this well predated the legal change, the agency approached the quarry operators to investigate further and determine if well modifications would reduce water level fluctuations in the creek.
To determine if there was a definitive link from the dried-up stream to pumping at the high-capacity well, the Kraemer Company agreed to notify DNR groundwater and drinking water staff the next time gravel washing dates were scheduled.
When the advance notice came, stream flow was measured in Cook Creek daily for one week prior to pumping in numerous locations to document the stream conditions. DNR staff was also on the scene to measure stream flows the day the well began pumping. Segments of the stream ceased flowing four hours after pumping began, and the water began to flow again over the weekend when the quarry well was not in use. When pumping began again on Monday morning, portions of the stream once again dried up.
DNR investigators met with Kraemer Company representatives and staff from the Wisconsin Geological and Natural History Survey (WGNHNS) to discuss the problem. The survey provides objective scientific information about geology and water resources for informed decision making by government, industry, business, and individual citizens.
With permission from Kraemer Company, WGNHNS lowered special probes and equipment down the well to measure the characteristics of the rock in the borehole. They concluded the well intercepted a large fracture in the rock at 106 feet deep – the same approximate elevation as Cook Creek. Tests showed led investigators to conclude that water contained within this fracture drains to the bottom of the 550-foot-deep well at a rate of about 90 gallons per minute around the clock, even when the well isn't operating and is absorbed into the lower aquifer. The fracture could lose approximately 134,000 gallons of water every day. However, the well was used only about 20 days a year, and pumped an average of 80,000 gallons per day to wash gravel. On days when the well operated, the pump created suction in the borehole, which drew water more readily from the fractured part of the bedrock than from the bottom of the well. This drawdown lowered the normal water table in the well and surrounding rock and extended at least 350 feet away from the well, effectively draining portions of Cook Creek dry.
Casing a solution
Representatives from the Kraemer Company, the Department of Natural Resources and the Geological and Natural History Survey met in March 2006 to review test results and discuss possible solutions.
When the Mollett Quarry well had been drilled, the hole definitely bored through two distinct groundwater aquifers, but the well casing and grouting did not extend far enough to isolate and seal one aquifer from the other. A layer of confining rock between the two aquifers ordinarily limited downward movement of groundwater from the upper aquifer into the deeper aquifer, so groundwater in that upper layer flowed laterally instead of vertically. This lateral flow supplies water to Cook Creek. Analysis showed the bored well provided a conduit that connected the two aquifers.
In situations where shallow aquifers become contaminated, environmental rules require new wells to be drilled deeper to tap into clean, uncontaminated water supplies. Those wells are cased and grouted all the way down into the deeper aquifer to protect the water supply from contaminated water in the shallower aquifer. The same concept was proposed for the Mollett Quarry: By casing and grouting the well much deeper, it would seal off the shallower aquifer feeding the stream. Then, when the pump drew water, it would only draw from the lower aquifer, which would not affect the stream flow. Kraemer Company agreed to the modifications and hired a contractor in April 2006 to add 300 feet of casing and grout to their Mollett Quarry well.
After the well renovation, the water flow in Cook Creek was again monitored for a week before the next gravel washing operation and was flowing just fine. On June 13, 2006 the well pump was turned on. The babbling brook continued its noisy way downstream, tumbling over rocks and against the steep hillside throughout the three weeks when gravel was washed. The volume of water in Cook Creek's headwaters remained steady and was unaffected by water withdrawal from the quarry well.
Thanks to this cooperative project among landowners, industry and government, water flows steadily in Cook Creek's spawning and nursery areas, and the quarry has plenty of water for gravel washing from its high-capacity well.
Understanding what can't be seen
Testing and research provided clues about the nature of groundwater near the well, but there are no detailed maps of underground geology and aquifers. Researchers envision underground conditions by extrapolating from the information gathered when wells are drilled and test holes bored. For instance, wells drilled in the vicinity of proposed high-capacity wells offer clues to the depth of groundwater and specific bedrock found in a given locale. Well construction reports filed by drillers for every well they bore detail the groundwater depth and kinds of rock encountered at every drill site. These reports document how variable geology can be even in wells that are very close to each other. Groundwater levels can change with increased pumping, so we must remain watchful and invest in groundwater monitoring.
Although we can't see underground, we can use every available source of information to build a clearer picture of what's happening underfoot. The WGNHS has studied and published detailed geology and groundwater reports for Wisconsin counties. An advisory committee of county officials, DNR staff, University of Wisconsin-Extension staff, and other interested parties review these reports. The studies are consulted when local officials examine proposals for high-capacity wells, municipal wells, community pools and other developments that might draw significant amounts of water.
As we gather more information about groundwater, and as we become more knowledgeable about our groundwater resources, we can periodically refine the groundwater law to better protect streams and springs through the permitting process. A recent proposal for a high-capacity well located approximately 375 feet from a classified trout stream in La Crosse County is a case in point. The property owner's land did not extend the minimum distance of 1,200 feet from the stream as required by the new groundwater law. A WGNHS study, "The Geology of La Crosse County," noted the average depth to bedrock in the area was reasonably shallow. If the proposed well was cased and grouted to a depth of 170 feet, regulators reasoned the well would be sealed off from the upper aquifer that fed the stream. Based on that study, when the permit was issued, it required additional casing. Without the benefit of the detailed report, permit drafters would have required only 60 feet of casing, which may not have been enough to protect water levels in the stream.
Many people share the credit for restoring a steady flow of water to Cook Creek. Concerned neighbors called for investigators. Investigators called for additional technical help. The Kraemer Company granted access to its well to collect detailed bedrock data, and once a problem was discovered, the firm took quick, decisive action on its own to fix it. Collaborative work by landowners, business owners, the Vernon County Land and Water Conservation Department, the Department of Natural Resources and the Geological and Natural History Survey unraveled the problem and devised a solution.
It's fun to be a part of the solution when we can explain what happened and the owners are ready to do what needs to be done to resolve the situation, says Dave Hart, hydrogeologist, who examined the borehole for the Wisconsin Geological and Natural History Survey.
We are drawn to water, to the comforting sound of water tumbling over rocks, and to the sight of fish rising to the surface to feed. Water quenches our thirst, and a steady supply of clean drinking water forms a connection and a lifeline to the natural world around us. Now Cook Creek once again flows through the daily lives of the Wallace family, and the fish and insects that also call it home.
Cindy Koperski helps manage watersheds as part of the Western Rivers Team from DNR's La Crosse office.