Nearly 50 dead trout have been found in Castle Rock Creek since an unattended pump malfunctioned at a large dairy operation and sent manure streaming 2 miles to the popular Grant County fishing destination.
The full extent of the fish kill wasn’t known Monday because the Class II trout stream’s waters are deep and murky this time of year, state Department of Natural Resources fisheries supervisor David Rowe said Monday.
“It’s hard to tell how affected the fishery is, but it’s not an overnight fix,” Rowe said. “It may take a while for it to recover, depending on how many fish were killed.”
In a few weeks, after remaining fish have had time to recover from the stress of the manure discharge, DNR personnel will use electricity to shock sections of stream, which stuns the fish so they can be counted.
Their numbers will be compared to results from previous surveys to guide decisions on restocking for the next few years, Rowe said.
But the DNR stocks streams like Castle Rock Creek with 1-inch fingerlings that may take a decade to grow to the 17-inch length of some of the trout that were found dead, Rowe said.
The DNR is continuing to investigate whether Randy and Rosalyn Mouw, the owners of Misty Morning Dairy on Wood Road northeast of Fennimore, violated their operating permit, said Mark Cain, an agency waste water engineer.
The state hired a hauler for $50,000 to empty Misty Morning’s 1 million-gallon manure pit in March 2013 when it was at risk of overflowing. The dairy had filed for bankruptcy and said it couldn’t pay a hauler. It later repaid the DNR.
In 2014 the department reissued the dairy’s permit for pollution discharges as a concentrated animal feeding operation, or CAFO, allowing the business to expand. The owners said they had 1,340 animals in 2013, and projected the number to increase to 1,719 in 2014.
Under Wisconsin law, CAFOs are supposed to be regulated more closely than smaller farms because of their potential to pollute. The dairy estimated it would generate 12.2 million gallons of liquid manure and 660 tons of solid waste in 2016.
The DNR issues general permits for dairy CAFOs with 1,000 to 5,720 animal units. More scrutiny is given to individual permit applications, which are required for more dairy animals or more than 1,000 non-dairy animals.
Sometime Wednesday night, a hose coupling failed on a portable pump that had been left running. The machine pumped manure from a hillside storage pit onto the ground for an unknown number of hours, Cain said.
There is no rule or regulation against allowing a pump to run unsupervised for that long, but it’s not a good idea, Cain said.
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“It would be recommended that they monitor and watch a system like that,” Cain said.
The Mouws didn’t return phone calls seeking comment. The pump was part of a machine the owners rented that also agitated the manure to make it flow more smoothly, Cain said.
The manure was being transferred from a 3.3-million-gallon storage lagoon at the top of a hill along Wood Road, Cain said. The lagoon was nearly full, so its contents were being pumped through a flexible conduit to a 3.9-million-gallon pit that was built about 18 months ago on the side of the hill, he said.
Cain said he didn’t know how much manure was spilled, and it may not be possible to estimate the volume if the owners don’t know how much was in the lagoon before and after the spill.
The DNR hasn’t tracked how much manure was retrieved from an area along Highway Q, where a berm was installed after the spill was discovered early Thursday, Cain said.
The manure was vacuumed into trucks and deposited back at the dairy. The owners are responsible for those costs.
Rowe said the odor of manure was still evident in the creek and manure residue could be seen up to the high-water mark on the banks.
Castle Rock Creek has pools as deep at 8 feet. DNR workers used dip nets for several hours Monday to find 25 dead trout on the bottom.
The stream is known to produce trout over 20 inches long, said longtime angler Chuck Horn, who lives on Wood Road and found the stream of manure from the dairy running on top of the snow in front of his house Thursday morning.
Horn said he belonged to a management committee in the 1990s that obtained about $500,000 in grants for several stream improvement projects including anti-erosion measures.
Runoff from surrounding pastures and farm fields has deposited sediment and nutrients that degrade trout habitat. The creek is classified as “impaired,” which means grants are available to do things like plant vegetation aimed at reducing the amount of soil and manure carried into the water by rain.
Over the weekend, the local fire department spent several hours spraying water on the manure trail through the snow and ice along Wood Road.
The effort ended when the pool along Highway Q threatened to flow over the berm, Horn said.
Class II trout streams are cold and clear enough to support some natural reproduction, but they must be stocked annually.