Section 319
NONPOINT SOORGE PROGRAM SOGGESS STORY
Implementing Best Management Practices and Targeting Technical
Assistance Improve Powers Lake
A/ t h H I H Elevated nutrient levels caused frequent algae blooms in North
VVaterDOay imprOVea Dakota-s powers Lake. As a result, the North Dakota Department
of Health (NDDH) added Powers Lake to its 2002 Clean Water Act (CWA) section 303(d) list as fully
supporting, but threatened, for the lake's recreation and aquatic life designated uses. Stakeholders
developed a watershed plan and implemented numerous best management practices (BMPs) on
agricultural lands. Data show that water quality has improved significantly and some water quality
targets are being met. The lake, however, will remain listed as impaired (threatened) while watershed
partners work to remove phosphorus-rich lake bottom sediments.
Problem
Powers Lake, a 1,616-acre natural freshwater lake
in northwestern North Dakota, is an important
recreational resource (Figure 1). The lake drains
approximately 44,458 acres of primarily agricultural
lands (crops and livestock). In the mid-1990s local
residents became increasingly concerned about
deteriorating water quality and reduced recreational
opportunities as the lake experienced frequent
blue-green algae blooms in mid- to late summer and
fish kills in both the summer and winter. In response,
watershed stakeholders partnered to form the
Powers Lake Advisory Committee (PLAC) in 1998.
In 1999, with assistance from the NDDH's Division of
Water Quality, PLAC initiated a water quality assess-
ment project to monitor water quality, inventory
current land use practices, and generate pollution
estimates using the Agricultural NonPoint Source
(AGNPS) model. Modeling results indicated that
Powers Lake received an annual phosphorus load of
11,564 pounds (Ib)—6,339 Ib from external sources
and 5,225 Ib from internal sources (nutrient cycling).
North Dakota relies on Carlson's Trophic State
Index (TSI) as the primary indicator for assessing
beneficial uses of lakes. Carlson's TSI is derived
from several measures of water quality, includ-
ing turbidity (using Secchi disk depth recordings),
chlorophyll a concentrations (algal biomass), and
total phosphorus levels. A high TSI score indicates
a more productive lake. Based on Carlson's TSI and
water quality data collected between March 2001
and October 2001, NDDH and PLAC determined
that Powers Lake was a nitrogen-limited hyper-
eutrophic lake. On the basis of these data, NDDH
added the lake to the 2002 CWA section 303(d) list
Powers Lake, North Dakota
Powers Lake
Williston
Legend
• City of Powers Lake
• Cities/Towns
— Major Highways
Minor Highways
I I County Boundary
Fargo
Figure 1. Powers Lake extends southward from the City of Powers
Lake in northwestern North Dakota.
as fully supporting, but threatened, for its recreation
and aquatic life designated uses.
In 2008 NDDH developed a total maximum daily
load (TMDL), which indicated that the recreational
use impairments in Powers Lake were associated
primarily with nonpoint source pollutants from agri-
cultural lands, including nutrients (phosphorus) and
suspended sediments. Potential pollutant sources
included tilled croplands, overgrazed rangeland,
and livestock winter feeding areas. According to
the TMDL models, nutrient loading to Powers Lake
must be reduced by 75 percent from external sourc-
es and 50 percent from internal sources to restore
the lake to the target trophic state of eutrophic
(between 50 and 70 TSI) rather than hypereutrophic
(TSI of greater than 70). Because chlorophyll a is
the TSI variable most accurate at predicting algal
biomass, the TMDL identified a chlorophyll a TSI
of 55.02 as the TMDL target needed to achieve the
water quality improvement goal.
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Figure 2. Some farmers
implemented no-till management
in the Powers Lake watershed.
Project Highlights
The 1999 watershed assess-
ment and AGNPS modeling
allowed PLAC to develop a
watershed restoration action
strategy that identified ben-
eficial use improvement and
pollutant reduction goals,
outlined specific activities
for accomplishing the goals
and established a method for
evaluating progress. Thanks
to these efforts, PLAC began
targeting conservation planning assistance and
voluntary implementation of BMPs in high-priority
subwatersheds as early as 2003, including:
• Implementing 12,013 acres of nutrient manage-
ment and an additional 15,476 acres of no-till
management (Figure 2)
• Improving grazing management on 4,790 acres
• Converting 978 acres of cropland to hayland
• Installing 72,876 feet of livestock fencing
• Installing nine sediment dams and grass buffers
and protecting 3,940 feet of riparian area.
PLAC project staff also worked closely with the
North Dakota Game & Fish Department, the North
Dakota Natural Resources Trust, and the U.S. Fish
and Wildlife Service, which provided technical and
financial assistance to create or restore 11 wet-
lands, seed 176 acres in grass, and protect 167 feet
of shoreline and riparian areas. In addition, local Soil
Conservation District (SCO) staff worked coopera-
tively with local Natural Resources Conservation
Service (NRCS) personnel to identify and tap all
available funding assistance programs.
Results
Monitoring data collected between 2001 and 2009
indicate that TSI scores for Secchi disk transpar-
ency and chlorophyll a are improving (Figure 3).
The average TSI score for chlorophyll a in 2009
was 53.24, which meets the TMDL target of 55.02.
The phosphorus TSI scores, however, are high and
holding steady at around 85 (in the hypereutrophic
range), likely because in-lake phosphorus is continu-
ally recycled from the lake's bottom sediments.
A 2009 feasibility study found that selectively
2001
2006
2007
2009
Year
Figure 3. Average TSI scores show improving trends for
chlorophyll and Secchi disk transparency in Powers Lake,
2001-2009.
removing lake sediments would best reduce the
internal phosphorus cycling. In 2011 PLAC received
CWA section 319 funding to conduct the sediment
removal, which is expected to be completed by the
end of 2015. Although the TMDL target was met by
2009, Powers Lake will remain listed as impaired
until the high phosphorus levels are also addressed.
Partners and Funding
PLAC was formed by local educators; local citizens;
and representatives from the City of Powers Lake,
Mountrail and Burke counties (including SCO and
NRCS offices), and local townships. The Mountrail
County SCO served as the fiscal agent for the project.
PLAC hired staff to develop BMP contracts for agri-
cultural producers and deliver technical assistance.
Project staff worked closely with partners at the
federal, state and local level to support the project.
In 2003 the U.S. Environmental Protection Agency
awarded $418,349 in CWA section 319 funds to
support the project; these funds were matched by
$278,900 in local funds (cash and in-kind services)
from agricultural producers, PLAC, and state and
local stakeholders. PLAC received $282,350 in CWA
section 319 funds in 2011 (with $188,233 in match-
ing funds) to support the removal of phosphorus-
rich lake sediments.
NDDH provided oversight for project management,
developed the quality assurance project plan,
conducted water quality monitoring training, and
helped to develop and implement information and
education activities.
I
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-12-001P
June 2012
For additional information contact:
Kenny MacDonald, Powers Lake Advisory Committee,
Mountrail County Soil Conservation District
701-464-5055 • plwatershed@yahoo.com
Greg Sandness, North Dakota Department of Health
701-328-5232 • gsandnes@nd.gov
Eric Steinhaus, North Dakota Watershed Coordinator,
EPA Region 8
303-312-6837 • steinhaus.eric@epa.gov
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