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Implementing Best Management Practices Results in Bayou des
Cannes Meeting Its Standard for Total Dissolved Solids
WatprhnHv ImnrnvpH Bav°u des Cannes, subsegment 050101, was added to the Louisiana
Department of Environmental Quality's (LDEQ) 2008 Clean Water
Act (CWA) section 303 (d) list for not supporting its fish and wildlife propagation (FWP) designated
use, due to elevated levels of totai dissolved solids (TDS), The U.S. Department of Agriculture-
Natural Resources Conservation Service (USDA NRCS) as well as the Louisiana Department of
Agriculture and Forestry (LDAF) implemented best management practices (BMPs) in the watershed.
In December 2015, LDEQ Water Surveys began collecting water quality samples to monitor critical
areas and to evaluate water quality changes in the watershed. Recent data indicate the subsegment
no longer exceeds the TDS standard; as a result, LDEQ removed the waterbody's FWP impairment,
due to TDS, from the state's draft 2018 Integrated Report (IR).
Problem
Bayou des Cannes is a 68-mile perennial stream
located in southwestern Louisiana. The northern por-
tion of the watershed is characterized by rice, pasture-
land and soybeans, and the southern segment features
aquaculture, rice and a large area of forested wetland.
The watershed is sparsely populated outside of its
municipalities (Figure 1). Excessive nutrient deposition,
stemming from agriculture, led to increased concen-
trations of TDS in the watershed.
TDS data collected during the 2007-2008 ambient
water quality network (AWQN) monitoring cycle
revealed four of 11 samples (36%) exceeded the stan-
dard (i.e., no more than 25% of samples may exceed
260 milligrams per liter [mg/L]) (Figure 2). Therefore,
Bayou des Cannes was listed on LDEQ's 2008 IR for not
supporting its FWP use. According to LDEQ's 2016 IR,
the waterbody's FWP use remained impaired due to
high levels of TDS, in addition to increased concentra-
tions of turbidity, nitrate-nitrite, phosphorus (P), and
low concentrations of dissolved oxygen (DO).
Story Highlights
Between 2009 and 2018, USDA NRCS and LDAF
implemented BMPs in Bayou des Cannes to reduce
erosion, sedimentation and nutrient runoff (Table 1).
Outreach activities were initiated before and during
BMP implementation to educate landowners on the
Figure 1. Land use in Bayou des Cannes.
importance of reducing agricultural impacts to the
environment. During local soil and water conservation
district (SWCD) meetings, technical specialists pre-
sented details on the bayou's water quality impair-
ments, sources, causes, and methods of remediation.
1201030'
[ 080802010304
080802010307
[legend j
CLASS
—
Rice
Aquaculture
Woody Wetlands

Soybeans

Developed

Grass/Pasture

Other cropland

Other shrub/barren

Fallow/Idle Cropland

Upland forest

Water
USDA HUC12 Boundary
® Bayou des Cannes Sampling Sites
o Ambient Water Quality Network Site
— Stream
Bayou des Cannes
Subsegment 050101
Land Use/Land Cover

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Table 1. Practices installed in the watershed by NRCS
2009-2016) and LDAF (2015-2018).

Amount installed
Practice type
By NRCS
By LDAF
Irrigation land-leveling (acres [ac])
9,102
3,759
Brush management (ac)
135

Forage and biomass planting (ac)
723

Grade stabilization structures
256
51
Heavy use protection areas (ac)
2,175

Irrigation pipeline (feet [ft])
33,838

Livestock shade structure
1

Nutrient management (ac)
419
8,857
Pasture and hay planting (ac)
96

Prescribed grazing (ac)
266

Shallow water development (ac)
10,368

Watering facilities (ac)
10

Critical area planting (ac)
0.5

Fencing (ft)
6,242

Mulching (ac)
0.5

Prescribed burning (ac)
92

Water control irrigation
6

Water pipeline (ft)
34,257

Irrigation water management (ac)

7,783
Conservation crop rotation (ac)

10,225
Pest management (ac)

8,817
Shallow water for wildlife (ac)

2,568
LDAF began implementing BMPs in March 2015,
focusing initially on the central and northern areas
of the subsegment, which were identified by LDAF as
having significantly larger coverage and total acreage
of intense agricultural land uses known to cause the
impairments. High-priority areas were based on land
use/land cover data, output from the Soil and Water
Assessment Tool (SWAT) model, and AWQN monitor-
ing data. Output from the model was used to identify
critical areas within those prioritized by LDAF, to help
develop ranking criteria for selecting applications
for implementation. Thirty-four applications have
been received and 29 contracts have been written.
Implementation will continue through 2023.
LDEQ Water Surveys began collecting water quality
samples and in-situ readings at seven locations for
field parameters and nutrients in December 2015.
The sampling effort entails monitoring critical areas
Bayou des Cannes Ambient Data, 2003-2016
^ 450
Limit: 260 mg/L
Figure 2. Bayou des Cannes TDS data, 2003-2016.
identified by SWAT, evaluating water quality changes,
and utilizing data to aid in future placement of BMPs.
Sampling sites were selected based on watershed
drainage and hydrology, SWAT results, land use data,
implementation areas, and accessibility. In-stream
baseline data was collected for 12 months. Long-term
monitoring began in January 2017, and will continue
throughout the implementation period. Post-BMP
monitoring will be performed for approximately one
year after implementation. LDEQ developed a water-
shed implementation plan in 2017.
Results
TDS data collected from October 2015 to August
2016 show two of 11 samples (18%) exceeded the
standard (Figure 2). Based on these data, the subseg-
ment currently supports its FWP designated use due
to decreased TDS; as a result, LDEQ removed TDS as a
cause of impairment in the draft 2018 IR. The subseg-
ment remains impaired for failing to support its FWP
use due to excessive nitrate-nitrite, total P, turbidity,
and low DO concentrations.
Partners and Funding
The U.S. Environmental Protection Agency, LDEQ,
LDAF, the Evangeline Parish SWCD, and USDA NRCS
are responsible for improving the water quality in
Bayou des Cannes. LDAF has allocated approximately
$927,000 for BMP activities, of which $358,132 has
been expended. Approximately $481,992 has been
received in matching funds. LDEQ has allocated
approximately $200,640 ($120,384 federal and
$80,256 matching funds), for LDEQ nonpoint source
staff activities, and water quality sampling and analy-
sis. The USDA NRCS's total financial assistance
obligation was approximately $2,729,790.
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-19-001F
February 2019
For additional information contact:
John Sheehan
Louisiana Department of Environmental Quality
225-219-0879 • john.sheehan@la.gov

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