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NONPOINT SOIREE SICCESS STORY
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Watershed Work Restored Native Freshwater Mussels in Lime Creek
Waterbody Improved Wit'1 increasing amounts Of soil washing iri, Lime Creek was
struggling to support the native freshwater mussels living in its
waters, landing a portion of it on Iowa's impaired waters list in 2002. But this wasn't an overnight
change; studies showed the mussel population declined between 1984 and 1998 largely due to
extra sediment and nutrients washing into the stream from row-cropped fields in the watershed.
In response, local farmers formed the Lime Creek Watershed Council. The group encouraged better
farmland management practices to reduce erosion, which helped improve mussel habitat in the
creek. A recent Iowa Department of Natural Resources (DNR) mussel survey showed the population
had rebounded enough in one segment of Lime Creek for it to be removed from the Clean Water
Act (CWA) section 303(d) list (the state's list of impaired waters) in 2014.
Problem
Lime Creek drains a long, narrow area of land (27,039
acres)—much of it planted in corn and soybeans—in
eastern Iowa (Figure 1). Smallmouth bass anglers and
visitors to the Lime Creek park area near Brandon,
managed by the Buchanan County Conservation
Board, regularly make visits to this stretch of stream,
now featured on the state's list of Outstanding Iowa
Waters. However, this tributary to the Cedar River
hasn't been without its problems.
A 1984 freshwater mussel survey found nine species
of mussels, but by 1998, a follow-up survey found no
live mussels. As a result, the lower segment of Lime
Creek landed on Iowa's impaired waters list in 2002 for
failing to meet its designated use of supporting aquatic
iife. In addition, monitoring by Coe College between
2002 and 2005 showed that nitrate concentrations in
Lime Creek were the highest of seven nearby tribu-
taries of the Cedar River, which serves as a drinking
water source for the city of Cedar Rapids, 25 miles
downstream.
In July 2008, more than 2,700 fish were found dead in
Lime Creek. Because the fish kill was reported more
than 48 hours after it occurred and it happened during
high flow conditions, the cause of the kiil was never
determined. One month later, the stream was sampled
as part of Iowa's stream reference network, and the
fish had recovered enough that the stream's Fish Index
of Biotic Integrity score passed.
Figure 1. The Lime Creek watershed is in eastern Iowa.
Story Highlights
The effort to reclaim Lime Creek took some muscle
and effort from the community. Farmers, livestock
producers and other residents of Lime Creek came
together over concerns about the creek's water quality
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'BENTON
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BLACK
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Lime Creek
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BUCHANAN
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Figure 2. Lime Creek, seen here at the Benton County/
Buchanan County line, in 2007 (left) and 2018 (right),
offers improved native mussel habitat.
and high nitrate levels downstream in Cedar Rapids.
Forming the Lime Creek Watershed Council, the group
kicked off on-farm conservation efforts in 2006 with
initial funding from the Iowa Corn Growers Association
(ICGA). A year later, the council, with assistance from
Iowa State University (ISU) Extension and Outreach,
applied for and received funding from the Iowa
Watershed Improvement Review Board (WIRB) and
partner organizations to put more on-farm conserva-
tion practices into use. Facilitated by Extension staff
and supported by the U.S. Department of Agriculture's
Natural Resources Conservation Service, the project
developed a performance-based incentive program
to fund farming practices that reduce nutrients and
sediment reaching Lime Creek.
Almost half of rural watershed residents participated
in the project, enrolling in the incentive program to
make changes on their land (Figure 2). Many producers
reduced tillage and adjusted crop rotations to increase
crop residue, while others looked at changes to nutri-
ent application or installed grassed waterways or a
bioreactor to reduce nutrients washing off the land.
Project activities have continued voluntarily through
the Lime Creek Watershed Council.
Results
Thanks to conservation practices adopted by farmers
and landowners, the amount of sediment reaching the
creek dropped by about 959 tons each year (enough to
fill 64 dump trucks) and reduced phosphorus levels by
about '1,462 pounds per year. In addition, water moni-
toring showed that average nitrate-nitrogen (N03-N)
concentrations in Lime Creek dropped 19 percent.
Reducing the sediment washing Into Lime Creek
improved the creek's native mussel habitat. The Iowa
DNR's statewide mussel survey, funded by a U.S.
Figure 3. Lime Creek watershed farmer and
conservation leader Dick Sloan (middle) stands in a
field of cereal rye he grows for cover crop seed.
Environmental Protection Agency (EPA) CWA section
319 grant, showed that the number of mussel species
in Lime Creek had rebounded from zero in 1998 to six
in 2011. Three of the species found are listed by Iowa
as threatened: ellipse (Venusaconcha ellipsiformis),
cylindrical papershell (Anodontoidesferussacianus)
and creeper (Strophitus undulatus). As a result, Iowa
removed one segment of Lime Creek from the state's
list of impaired waters in 2014.
Lime Creek was placed on the list of Outstanding Iowa
Waters as an outstanding state resource in 2010 due
to its exceptional ecological significance. As a refer-
ence site for ecosystems in the region, Lime Creek
consistently scores very well on studies that look at the
diversity and health of animals and plants that live in
the water (other than mussels), such as crayfish, snails,
dragonfiies and other aquatic insects. The mussels that
live there won't survive just anywhere, either—the
ellipse mussel and its fish hosts are both very sensitive
to habitat disturbance and water quality declines—
their survival depends upon the cleaner water now
found in Lime Creek (Figure 3).
Partners and Funding
Partners providing funding and technical assistance
to the Lime Creek Project included the Iowa WIRB
($202,710), ICGA ($90,000), Cedar River Monitoring
Coalition ($32,800), ISU ($28,241), Lime Creek
Watershed Council ($7,950), NRCS ($4,280), Buchanan
County Extension ($375), and project cooperators
($72,049). Project funding totaled $438,405. The
Iowa DNR statewide mussel survey was funded by a
$253,060 EPA CWA section 319 grant.
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©
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-18-Q01UU
December 2018
For additional information contact:
Jennifer Kurth
Iowa Department of Natural Resources
515-725-8381 • jennifer.kurth@dnr.iowa.gov

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