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Implementing Agricultural Conservation Practices Improves Turbidity
Levels in Cottonwood Creek
Waterbody Improved E'evatec' turbidity resulted in the impairment of Cottonwood Creek
and placement on Oklahoma's Clean Water Act (CWA) section
303(d) list of impaired waters in 2006. Grazing, hay production, cropland management and urban
development contributed to these impairments. Implementation of conservation practice systems
(CPs) to improve agricultural land management, education and improved stormwater management
decreased turbidity in the creek. As a result, the downstream segment of Cottonwood Creek was
removed from Oklahoma's 2010 CWA section 303(d) list for turbidity. The delisted segment of
Cottonwood Creek now fully supports its fish and wildlife protection (FWP) beneficial use.
Cottonwood Creek is a 46.4-mile stream that flows
through Kingfisher, Canadian. Oklahoma, and Logan
counties before discharging to the Cimarron River
(Figure 1). Land use in the 243,420-acre watershed
is primarily pasture and grasslands (38 percent of
total). About 25 percent of the watershed is cropland
(primarily wheat), 11 percent is forested, and approxi-
mately 24 percent is developed land that Includes
portions of the Oklahoma City metropolitan area.
Because Cottonwood Creek is historically flood-prone,
an extensive network of upstream flood control
structures was established to protect citizens and
infrastructure (see Figure 1). These 16 structures built
between 1965 and 1973 have successfully reduced
flooding and also capture an estimated annual average
of 100,880 tons of soil from upstream areas. These
structures provide approximately $409,000 in annual
savings due to avoided flooding damages that benefits
174 farms or ranches in the watershed and protects a
network of 13 bridges. Construction of these struc-
tures has created or enhanced 484 acres of wetlands.
As a result of the age of the structures and down-
stream development, some needed eroded spillway
repairs while others needed renovation to better
protect new downstream development.
Grazing land and cropland management and urban and
infrastructure development contributed to excess tur-
bidity in Cottonwood Creek. It was listed as impaired for
turbidity in 2006 when 26 percent of assessed baseflow
turbidity samples violated water quality standards. An
¦ ¦
- rr^HiT^jrm
Oklahoma City
• Monitoring Site
— Delisted Cottonwood Creek Segment
6 Cottonwood Creek Upstream Flood Control Structures
Cottonwood Creek Landuse
H Water
Open Space Development
Low Intensity Development
Medium Intesity Development
High Intensity Development
Deciduous Forests
Evergreen Forests
^3 Pasture/Hay Lands
Crop Lands
| Wetlands
Figure 1. Cottonwood Creek is in central Oklahoma.
Oklahoma stream is considered to violate the turbid-
ity 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 a 22.01-mile segment of Cottonwood
Creek (OK620910040010_00) to the 2006 CWA section
303(d) list for nonattainment of its FWP beneficial use.
Project Highlights
Landowners worked with the East Canadian,
Kingfisher, Oklahoma, and Logan county conserva-
tion districts, the U.S. Department of Agriculture
(USDA) Natural Resources Conservation Service
(NRCS), and the Oklahoma Conservation Commission
(OCC) to implement CPs through Oklahoma NRCS's
Environmental Quality Incentives Program (EQIP) and
general conservation technical assistance program, as

well as through OCC's Locally Led Cost-Share Program
(LLCP). From 2006 to 2012, landowners improved
grasslands and croplands, which reduced runoff of
sediment and other pollutants, CPs installed included
brush management (546 acres), conservation crop
rotation (35 acres), contour farming (206 acres), critical
area planting (19 acres), forage and biomass planting
(256 acres), grassed waterway (12 acres), one ground-
water testing event, nutrient management (337 acres),
prescribed grazing (470 acres), no-till (558 acres), two
ponds, range seeding (75 acres), seasonal residue
management (74 acres), terraces (187 feet) and one
water well.
Rehabilitation of upstream flood control structures
in the watershed also improved water quality in the
basin. Rehabilitation on one dam was completed in
January 2011; another dam was decommissioned In
July 2012. A third structure will be rehabilitated in the
fall of 2017. These projects reduce erosion by stabiliz-
ing structures and can also increase sediment and
floodwater storage. The structure decommissioning
involved dam removal and site regrading and revegeta-
tion to stabilize slopes and tie the stream channel back
into natural configuration.
Blue Thumb volunteers monitor three sites in
the Cottonwood Creek watershed. As part of the
Oklahoma City and Edmond area efforts, Blue Thumb
and participating partners also conduct frequent edu-
cation events such as natural resource days, volunteer
trainings, and other activities that educate citizens
about water quality. Finally, Edmond and Oklahoma
City have been growing their stormwater programs,
resulting in increased regulation and compliance from
the construction industry. Oklahoma City has a robust
stream monitoring program with multiple sites in the
watershed; they use data from the program to inform
stormwater policies and remedial projects.
The OCC documented improved water quality in
Cottonwood Creek through its statewide nonpoint
source Rotating Basin Ambient Monitoring Program.
The management changes decreased erosion and
reduced turbidity. Monitoring data compiled for the
2006 Integrated Report showed excessive turbidity
in Cottonwood Creek when 26 percent of baseflow
samples exceeded the state standard of 50 NTU.
Cottonwood Creek Turbidity
% exceedance: 0% 26% 27% 8% 0% 8% 7%
~ 1 ~

5" 250.00
3	150.00

t • ~ ~ ~

! i i 1 I i i

2004 2006 2008 2010 2012 2014 2016
Figure 2. Turbidity levels decreased as conservation
efforts increased in the watershed.
However, by 2010, turbidity values had decreased such
that only eight percent of samples exceeded 50 NTU;
this decreasing trend continues through the 2016
assessment (Figure 2).
On the basis of these data, the lower segment of
Cottonwood Creek was removed from the Oklahoma
CWA section 303(d) list for turbidity in 2010. This
change resulted in full support of its FWP beneficial
use. Future monitoring efforts will assess the upstream
segment to determine if improvements also exist in
that segment.
Partners and Funding
The OCC Rotating Basin Monitoring and Blue Thumb
programs are supported by the U.S. Environmental
Protection Agency's (EPA) CWA section 319 grant
program, with approximately $1.5 million invested
annually. OCC invested approximately $340,000 in
monitoring and education programs in the watershed
between 2006 and 2010, funded by section 319. NRCS
supplied approximately $31,000 for implementation
of CPs in the watershed through NRCS EQIP. The LLCP
provided $28,398 matched by $28,646 from land-
owners. A large number of practices were funded by
landowners based on recommendations through NRCS
general technical assistance and conservation plan-
ning. Upstream flood control structure rehabilitation
and decommissioning was funded with $997,500 in
state funds and $1,852,500 from USDA NRCS.
U.S. Environmental Protection Agency
Office of Water
Washington, DC
W .1
^ EPA 841-F-17-001H
pR0*t^° August 2017
For additional information contact:
Shanon Phillips
Oklahoma Conservation Commission
405-522-4500 • shanon.phillips@conservation.ok.gov