Section 319
NONPOINT SOURCE PROGRAM SUCCESS STORY
Restoration Efforts Repair a Drinking Water Source and Recreational Area
\A/ t h H I H Erosion from heavily grazed pasture lands and intensively farmed
WdLei UUUy II ipi UvtJU cropland caused excessive siltation in Iowa's Lake Icaria, triggering
the Iowa Department of Natural Resources (IDNR) to place the lake on the state's 1998 303(d) list of
impaired waters. The local Soil and Water Conservation District realized that the lake, which serves as
both an important water supply and recreation area, was being slowly degraded. They began working
with landowners in the upper reaches of the watershed to install agricultural best management prac-
tices (BMPs) that reduce soil erosion. Their efforts were successful—water quality improved, and IDNR
removed Lake Icaria from Iowa's 2008 303(d) list of impaired waters for sediment.
Problem
The 669-acre Lake Icaria is in southwest Iowa's
Adams County, adjacent to a cluster of small lakes
that supply drinking water to surrounding communi-
ties. The watershed consists of active cropland,
pasture lands, and small portions of retired cropland
converted to grassland as part of the Conservation
Reserve Program. The lake is surrounded by a
county-owned park and serves as a popular com-
munity destination for recreation and fishing.
Increasing sediment loads originating from agri-
cultural practices in the upper reaches of the
watershed began reaching the lake and degrad-
ing the water quality. IDNR first added the lake to
Iowa's 303(d) list of impaired waters in 1998. A
December 2002 total maximum daily load (TMDL)
study determined that excess siltation contributed
to poor aquatic habitat, causing the lake to not
fully support its warm water habitat/aquatic life
designated use. Iowa does not have numeric water
quality criteria for siltation that apply to Lake Icaria.
Therefore, IDNR field staff members used their best
professional judgment of the water quality when
they added Lake Icaria to the list of Iowa impaired
waters.
Sediment affected Lake Icaria primarily by inter-
fering with reproduction and growth offish and
other aquatic life, particularly in the shallow, upper
portions of the lake that offer critical habitat for
spawning (70-90 percent of available habitat).
Although the entire lake was listed as impaired, it
was primarily the excessive sediment deposition
in the upper arms of the lake that caused the lake
to not meet water quality standards. The upper
reaches of the lake became covered with fine silt
that made successful spawning almost impos-
sible, severely limiting the fishery in the entire lake.
Additionally, the colloidal nature of the sediment
delivered to Lake Icaria created less-than-ideal feed-
ing conditions for sight feeders. Bass and bluegill
primarily feed along the shoreline, and the fry use
the shoreline's vegetative cover for protection from
predators. Reduced water clarity from sedimenta-
tion inhibits aquatic vegetation from growing, leav-
ing the smaller fish unable to feed successfully and
exposed to predation.
Project Highlights
Between 1996 and 2005, state and federal agencies
worked with landowners to promote and implement
numerous BMPs to alleviate the erosion within the
upper watershed. Practices include grade stabiliza-
tion structures, terraces, filter strips, pasture and
hay planting, grassed waterways, streambank
crossings and prescribed grazing systems. Partners
organized demonstration field days to show how
BMPs such as livestock management techniques
can reduce soil erosion in the stream corridor
(Figure 1). They also constructed a wetland along
Lake Icaria's largest
tributary as the last
line of defense for
trapping sediment
and nutrients. In
addition to the
water quality
benefits, the wet-
land offers other
benefits to wildlife
and hunters Figure 1. Landowners inspecting
":' ""' °' residue levels at a manure injection
field day.
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Results
This project was the first in Iowa to effectively use
a geographical information system (GIS) to initiate
detailed watershed assessment techniques. The
GIS has proven to be an efficient tool when map-
ping a watershed and planning strategic placement
of BMPs. GIS data for sheet/rill erosion indicates
that the practices implemented in the watershed
resulted in a soil-loss savings of 22,239 tons/year
(Table 1). Estimated sediment delivery rates
decreased from 12,095 tons/year pre-project to
4,350 tons/year post-project.
Assessments and surveys by IDNR's Fisheries
Bureau, Iowa State University and University
Hygienic Laboratory determined that Lake Icaria
now fully supports its aquatic life designated
use. The IDNR Fisheries Bureau indicated that the
extensive soil conservation practices implemented
in the watershed successfully reduced nutrient and
sediment loadings in Lake Icaria. As a result, IDNR
removed Lake Icaria from Iowa's 2008 303(d) of
impaired waters for sediment.
Partners and Funding
A variety of partners from local, state and federal
agencies combined efforts to ensure the project's
success. The project used approximately $500,000
of Clean Water Act section 319 funds to install 20
grade stabilization structures, four waste system
renovations, one stream crossing, one constructed
wetland, and to support the salary for the proj-
ect coordinator from 2001 to 2005. Additional
funds from Adams and Pottawattamie Counties'
Pheasants Forever and Ducks Unlimited supported
wetland construction.
Funds from the Natural Resources Conservation
Service helped to share the cost of implement-
ing BMPs on the estimated 3,052 acres that were
enrolled in the Conservation Reserve Program.
Iowa's Publicly Owned Lakes Fund provided cost-
share for installing 112,995 feet of terraces, 3 acres
of grassed waterways, and one sediment control
structure.
Iowa's Water Protection and Watershed Protection
Funds (WPF and WSPF) provided cost-share funds
for BMPs including 43,450 feet of terraces, 31
grade stabilization structures, 341 acres of pre-
scribed grazing, 32 acres of pasture and hayland
planting, one streambank crossing, one acre of
grassed waterway, and 987.4 acres of animal waste
management systems. The WPF and WSPF also
funded yield monitoring, water monitoring and the
project coordinator's salary.
The Environmental Quality Incentive Program
provided cost-share funds for three grade-stabiliza-
tion structures, 190 acres of prescribed grazing
systems, and 68 acres of pasture and hayland
plantings.
Table 1. Erosion and sediment delivery
reductions in tons/acre/year
Location
Lake Icaria
Sheet/Rill Erosion Reductions
Resulting from Project BMP
Installations
Before
82859
After
60620
Sheet/Rill
% Reduction
27%
Location
Lake Icaria
Sheet/Rill Sediment Delivery
Reductions Resulting from
Project BMP Installations
Before
12095
After
4350
Sediment
Delivery
% Reduction
64%
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-08-001M
September 2008
For additional information contact:
Steve Hopkins, Nonpoint Source Program Coordinator
Iowa Department of Natural Resources
515-281-6402 • Stephen.Hopkins@dnr.iowa.gov
Rachel Glaza, Nonpoint Source Project Officer
Iowa Department of Natural Resources
515-281-8158 • Rachel.Glaza@dnr.iowa.gov
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