Section 319
NONPOINT SDURCF PROGRAM SUGCESf STORY
Land Treatment Efforts Improve Water Quality
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Nebraska's Kirkmans Cove Reservoir had severe dissolved oxygen
prob|ems through the mid-1990s. High levels of sedimentation and
nutrients also impaired the reservoir. The Nebraska Department of
Environmental Quality (DEQ) added this waterbody to the state's 1998 Clean Water Act section 303(d)
list of impaired waters. In 2000 the Nemaha Natural Resources District partnered with several local,
state and federal agencies to initiate a Community Based Planning process. Through this locally led
process, the partners developed a Watershed Management Plan that incorporated a unique mix of cost
share and incentives to encourage farmers to implement a host of agricultural management practices.
The plan paid off, and water quality improved. DEQ removed the dissolved oxygen impairment for
Kirkmans Cove Reservoir from Nebraska's 2002 303(d) list.
Problem
Kirkmans Cove Reservoir is in southeast
Nebraska's Richardson County. It was
designed and developed as a multipurpose,
flood control/public use area. Part of the
Nemaha River Basin, the 160-acre reservoir
has a watershed of 4,896 acres of which 2,590
acres (53 percent) are used for crop produc-
tion. The reservoir had dissolved oxygen
problems linked to excessive nutrient loading
and organic enrichment. Data collected in
1997 and 1998 showed that the water column
average dissolved oxygen concentrations
fell below 5.0 milligrams per liter (mg/L) for
six of the eight water quality profiles. From a
sample size of eight, regulations would allow
only two violations of the assessment criteria.
Therefore, DEQ added the reservoir to the
1998 303(d) list because low dissolved oxygen
concentrations impaired the reservoir's benefi-
cial uses for aquatic life.
In 2002 DEQ developed a TMDL for total phos-
phorus to address dissolved oxygen problems.
The TMDL indicated that a phosphorus load-
ing reduction of 92 percent would be needed
to increase dissolved oxygen concentrations
above impairment levels.
Figure 1. One of several water quality basins
constructed in the watershed to complement land
treatment measures. These basins are effective at
controlling steep grades and trapping pollutants
that are mobilized during larger storm events. Each
structure is fenced to exclude livestock and alternate
livestock water is provided below the structure.
Project Highlights
Participation in the watershed project was
good—21 of the 36 landowners implemented
controls. Overall, project partners treated 1,911
acres of cropland with terraces, rehabilitated
seven existing water quality basins to increase
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sediment and water storage,
built four grade-stabilization
structures, converted 147 acres
of cropland to grass and cleaned
out an existing water quality
basin (built in 1996) on the prima-
ry reservoir inflow that provides
additional sediment storage.
Kirkmans Cove Reservoir - Dissolved Oxygen Assessment
Results
Data have shown that water
quality has steadily improved.
Reservoir data collected from
1999 through 2001 showed that
of eight profiles taken, only two
violated the assessment criteria.
Consequently, DEQ removed
Kirkmans Cove Reservoir from
the 2002 303(d) list for dissolved
oxygen impairment.
• Water Column Profiles
• violations
D Violations Allowed
1998 Listing 2002 De-listing
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1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Management Practice Implementation
Figure 2. Water quality profile data showing water quality improvement.
Dissolved oxygen conditions have continued
to improve through the course of the project.
From 2004 through 2007, only three of 40
profiles were found to violate the assessment
criteria. Although the TMDL identified a phos-
phorus loading reduction target of 92 percent,
the achieved reduction of 48 percent improved
oxygen conditions sufficiently to meet the dis-
solved oxygen standard.
Loadings of other targeted pollutants such as
sediment, phosphorus, nitrogen and atrazine
(a herbicide) have also decreased. Land treat-
ment measures in the watershed reduced
annual sediment loading by 54 percent,
phosphorus loading by 48 percent and nitro-
gen loading by 39 percent. Additionally, data
show that atrazine concentrations in the res-
ervoir exhibited a significant decreasing trend
(a = .05) from 1997 through 2007; overall, the
pre-project median atrazine concentration
declined by 59 percent.
Partners and Funding
The project was made possible through a strong
partnership of the Nemaha Natural Resources
District, U.S. Department of Agriculture (USDA)
Natural Resources Conservation Service,
Nebraska Environmental Trust, Nebraska
DEQ, U.S. Environmental Protection Agency,
Nebraska Game and Parks Commission,
Kirkmans Cove Watershed Council and water-
shed landowners/operators. Section 319 funds
supported land treatment technical assistance
($48,437), engineering design ($34,528),
management practice cost share and incentives
($566,301) and information/education ($3,453).
Additional sources of practice cost share and
incentive funds include the USDA Environmental
Quality Incentive Program ($115,699), Nebraska
Environmental Trust ($200,000) and Nemaha
Natural Resources District ($147,574). Project
partners implemented the majority of land
treatment measures from 2001 through 2007.
However, maintaining a high-quality reservoir
will continue to be a priority for the resource
management agencies, so they will continue to
maintain and implement traditional and nontra-
ditional practices as needed.
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-08-001T
September 2008
For additional information contact:
Paul Brakhage
Nebraska Department of Environmental Quality
402-471-4224 • paul.brakhage@ndeq.state.ne.us
Shawn Kreienhop
Nemaha Natural Resources District
402-335-3325 • skreienhop@nemahanrd.org
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