U.S. Water News Online
SLIP BLUFF LAKE, Iowa -- State fisheries biologist Mike McGhee knows all too well how a modest spring rain can spoil swimming and fishing conditions all summer long at Slip Bluff Lake.
When mixed with rain, the reddish clay that carpets the lake's timbered hills sloughs off into a network of ever-deepening gullies and empties into the lake below -- often leaving the water cloudy for weeks afterward.
``Those are not the kind of conditions people should expect from public waters,'' said McGhee, who has looked after rivers and lakes in south-central Iowa for decades.
Iowa is required by the federal Clean Water Act to calculate just how much daily pollution its impaired lakes and rivers can handle and still meet water quality standards. Called a ``total maximum daily load,'' or TMDL, the plan also serves as a blueprint for improving the health of a lake, stream or marsh.
The erosion that threatens Slip Bluff Lake is a natural process, but the steady buildup of silt shortens the life of the manmade lake. Turbid water threatens the lake's bass catfish and crappie. Swimmers stay away.
The lake is just one of 157 rivers, streams, ponds and wetlands on the TMDL list because they have been identified as polluted.
Three Iowa conservation groups sued the Environmental Protection Agency three years ago, claiming that the agency wasn't enforcing Clean Water rules requiring states to draft and follow through on TMDL plans. The lawsuit was settled last year, and one outcome was a requirement that Iowa and other states develop a schedule for filing TMDLs on impaired waters.
The Iowa Department of Natural Resources approved 15 TMDL plans in 2001 and expects to write 13 more in 2002, said Bill Ehm, program coordinator. The goal is to have a TMDL for each of the 157 polluted waterways within 10 years.
``Some states have been at it a little bit longer than us, but there are some that still haven't written their first TMDL yet,'' Ehm said. ``The thing to remember is this is going to take a while.''
The DNR held a dozen hearings across the state last month briefing residents on the pollution in the state's waters. More hearings are planned later this year.
Buildup of sediment and silt is the most prevalent problem, affecting 43 percent of the impaired waters on the list, according to the agency. Fertilizers, chemicals, dams, manure and other organic matter also are culprits.
At Slip Bluff Lake, the state spent $70,000 to build 11 earthen structures along gullies on the hillsides above the lake. Each structure features an earthen berm, which slows and diverts runoff into a pond.
``We're not going to be able to eliminate erosion and siltation ... but the biggest thing we're trying to do here is slow down the runoff to improve the lake,'' McGhee said. The work cost $70,000.
The state will spend another $136,000 on 17 similar structures this spring above Nine Eagles Lake, also hurt by runoff.
Other problems may require more challenging solutions. In some cases, dredging and other pricey remedies may be needed to reduce silt, nitrates and farm chemicals and other pollutants.
Ehm said the challenge also lies in getting farmers to adopt new methods that better protect water from chemicals, manure runoff and silt.
``Most farmers are now doing a good job of keeping the soil in their fields,'' Ehm said. ``The vast majority of sediment in those water bodies moved in during the 70s and 80s when we farmed fence row to fence row.''
Farmers want to cooperate but question the data that leads to lakes and streams being labeled as polluted, said Rick Robinson, environmental director for the Iowa Farm Bureau.
``We just need better quantitative data on what the pollutants are, where they are coming from and linking cause and effect. We're guessing in many cases,'' Robinson said.
Environmentalists worry that the program lacks the regulatory authority and proper funding to achieve the DNR's clean water goals.
``There needs to be some (enforcement) authority to make sure these cleanup plans can be implemented,'' said Susan Heathcote, of the Iowa Environmental Council.
Heathcote also said Iowa's list of impaired waters should be much longer than it is, and should be expanded when the state revises it later this year.
``It's important to remember, though, that we've come a long way from where we were a few years ago,'' she said. ``The department now recognizes we have some real pollution problems ... and now we just need to do a better job of educating the public and bringing them on board.''
Other projects include Clear Lake and Ventura Marsh, in Cerro Gordo County. The lake and marsh suffer from siltation problems, and the DNR has suggested dredging and land management changes in the cleanup plan.
In southwest Iowa, Lake Icaria and Lake of Three Fires are polluted by silt and nutrients and are among the lakes targeted for TMDL plans this year.
As part of the TMDL for Rock Creek Lake, in Jasper County, the DNR plans to couple dredging with shoreline erosion projects along the streams that flow into the lake.
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