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
``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
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
``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
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
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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