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Implementing Agricultural Conservation Practices Improves Bacteria
and Turbidity Levels in Main Creek
\A/ . i | |	i High bacteria concentrations and elevated turbidity resulted in
Waterbody Improved the |mpaimentofMa|nCreekand p|acementonok|ahoma,s
Clean Water Act (CWA) section 303(d) list of impaired waters in 2004 (Escherichia coli) and 2006
(turbidity). Pollution from grazing, hay production and cropland areas contributed to these
impairments. Implementing conservation practice systems (CPs) to promote better quality grazing
lands and improved cropland management decreased bacteria and turbidity levels in the creek. As
a result, Main Creek was removed from Oklahoma's 2010 CWA section 303(d) list for turbidity; it
has also been recommended for delisting for E. coli on the 2016 CWA section 303(d) list. Main Creek
now fully supports its warm water aquatic and primary body contact designated uses.
Problem
Main Creek is a 19.1-mile stream flowing through
Woodward and Major counties and into Woods
County, Oklahoma, before discharging to the Cimarron
River (Figure 1). Land use In the 25,000-acre water-
shed is primarily pasture and grasslands (40 percent of
total) for cattle and hay production. About 27 percent
of the watershed is forested and approximately 23 per-
cent is cropland used primarily for wheat production.
Poor grazing and cropland management contributed
to excess turbidity and bacteria in Main Creek. It was
listed as impaired for E. coli in 2004 when the geomet-
ric mean of samples collected during the recreational
season was 1,058 colony forming units/100 milliliters
(CFU). The primary body contact recreation designated
use is considered impaired if the geometric mean
exceeds 126 CFU for E. coli.
Main Creek was also added to the section 303(d) list
in 2006 because 17 percent of assessed baseflow
turbidity samples violated standards. An Oklahoma
stream is considered to violate the turbidity standard
when more than 10 percent of baseflow samples are
higher than 50 nephelometric turbidity units (NTU).
On the basis of these assessment results, Oklahoma
added Main Creek (OK620920010180_00) to the 2004
and 2006 CWA section 303(d) lists for nonattainment
of the warm water aquatic and primary body contact
designated beneficial uses.
Main Creek Watershed
Figure 1. Main Creek is in northwestern Oklahoma.
Project Highlights
Landowners in the watershed worked with the Major,
Woods and Woodward county conservation districts,
the U.S. Department of Agriculture's (USDA) Natural
Resources Conservation Service (NRCS) and USDA
Farm Services Agency (FSA) to implement CPs through
Oklahoma NRCS's Environmental Quality Incentives
Program (EQIP), Oklahoma's general conservation
technical assistance program, and FSA's Conservation
Reserve Program (CRP). From 2004 to 2010, landown-
ers improved many acres of pasture and grasslands,
which reduced runoff of bacteria and other pollutants.

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Main Creek, Turbidity
20%	17% 12% 6% 5% 5% 3%
exceed exceed exceed exceed exceed exceed exceed
90
_ 70
Z3
£ 60 ~ , t ~ *
J 50 	w	.	«-
2004 2006 2008 2010 2012 2014 2016
Main Creek, E. coff
Geomean = Geomean = Geomean =
4500	10sa3 2494	1114
Figure 2. Monitoring data indicate that turbidity levels
have met standards since 2010.
CPs installed included 5,537 acres of prescribed
grazing, three watering facilities and wells, forage and
biomass planting and nutrient management on 183
acres, 1,680 acres of brush management and 130 acres
of integrated pest management.
Landowners also focused on reducing erosion and
pollutant runoff from cropland through multiple CPs,
including 288 acres of conservation crop rotation, 195
acres of cover crops, native grass planting and nutrient
management on 181 acres, reduced tillage residue and
tillage management on 288 acres, and upland wildlife
habitat management on 121 acres.
Partners continued to implement CPs from 2011
through 2016, including 550 acres of livestock access
control, 241 acres of brush management, 584 acres
of conservation cover, 84 acres of nutrient manage-
ment, 7,019 acres of prescribed grazing, one well,
one pumping plant, one watering facility, 84 acres of
no-till residue and tillage management, and 69 acres of
reduced-till residue and tillage management.
Results
Through its statewide nonpoint source Rotating
Basin Ambient Monitoring Program, the Oklahoma
Conservation Commission (OCC) documented
improved water quality in Main Creek due to land-
owners implementing CPs. The installed grazing and
cropland management CPs worked to decrease erosion
and reduce bacteria. Monitoring data compiled for
the 2006 integrated report showed that turbidity in
Main Creek was high—17 percent of baseflow samples
Figure 3. Monitoring data indicate that bacteria levels
have declined and are now meeting standards.
exceeded the state standard of 50 NTU. However, by
2010 turbidity values had decreased to a 6 percent
exceedance rate. This decreasing trend continued
through the 2016 assessment (Figure 2). In addition,
Main Creek E. coli concentrations violated the state
standard of a geometric mean of 126 CFU in 2004
when the geometric mean was 1,058 CFU. However,
by the 2016 assessment, the geomean dropped below
the criteria (Figure 3). On the basis of these data, Main
Creek was removed from the Oklahoma CWA section
303(d) list for turbidity in 2010 and has been recom-
mended for delisting for E. coli in 2016. These changes
result in full support of its warm water aquatic and
primary body contact beneficial uses. Monitoring will
continue in Main Creek to ensure these water quality
improvements are maintained.
Partners and Funding
The OCC monitoring program is supported by the
U.S. Environmental Protection Agency's (EPA) CWA
section 319 funds at an average annual statewide cost
of $1 million. Approximately $500,000 in EPA CWA
section 319 funds support statewide water quality
educational efforts through Blue Thumb. From 2004
to 2010, NRCS supplied approximately $50,000 for
implementation of CPs in the watershed through EQIP.
From 2011 through early 2016, NRCS put an additional
$30,000 worth of CPs in the watershed through EQIP.
Additional funds were provided through FSA for CRP
practices. In addition, a large number of practices
were funded by landowners based on recommenda-
tions through NRCS general technical assistance and
conservation planning.
^edsj^ U.S. Environmental Protection Agency
0** Office of Water
^ Washington, DC
WJ
EPA 841-F-16-001AA
pro^° October 2016
For additional information contact:
Shanon Phillips
Oklahoma Conservation Commission
405-522-4500 • shanon.phillips@conservation.ok.gov

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