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(&z) NONPOINTSOIREE SICEESS STORY
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Implementing Agricultural Best Management Practices Reduces Total
Dissolved Solids in Bayou Queue de Ibrtue
Water body Improved ^ar '3ac'< as t'ie '-ou's'ana Department of Environmental
Quality (LDEQ) Integrated Report (IR) has indicated total dissolved
solids (TDS), total suspended solids (TSS), sedimentation/siltation and turbidity as impairments
to fish and wildlife propagation (FWP) use support in Bayou Queue de Tortue. LDEQ chose Bayou
Queue de Tortue, LDEQ subsegment 050501, as one of the 40 priority watersheds and partnered
with the Louisiana Department of Agriculture and Forestry (LDAF) and the U.S. Department of
Agriculture (USDA) Natural Resources Conservation Service (NRCS) to implement best management
practices (BMPs) to improve the health of the waterbody. The 2014 IR shows that FWP is no longer
impaired due to TDS. It remains impaired by turbidity, but water quality data show progress.
Problem
Bayou Queue de Tortue is 56 miles long and flows
from the city of Duson to the Mermentau River in
Riceville, Louisiana (Figure l).The bayou receives
much of its flow from agricultural runoff from rice and
soybean production, and is heavily hydromodified in
the upper and middle reaches. Dredging has.caused
a reduction in flow velocity and eroding spoil banks
have increased the amount of solids found in the water
column contributing to high turbidity and TDS.
LDEQ has listed the FWP use in this subsegment as
impaired since 2002 with suspected causes of impair-
ments including low dissolved oxygen (DO), turbidity,
TSS, TDS, sedimentation/siltation, phosphorus (total),
nitrate/nitrite (nitrate + nitrite as N), mercury in fish
tissue and Fipronil (a broad-spectrum insecticide).
Suspected sources of impairments were irrigated crop
production, atmospheric deposition-toxics, natural
conditions, flow alterations from water diversions, and
non-irrigated crop production.
Project Highlights
Figure 1. Southwestern Louisiana's Bayou Queue de Tortue
watershed is influenced by agricultural uses including
pastureland and rice and soybean production.
3,112.4 ac), nutrient management (590 sites; 17,052.2
ac), pest management (595 sites; 17,052.2 ac), record
keeping (tracking pesticide and nutrient use to avoid
overapplication) (748 sites; 17,052.2 ac), and dry seed-
LDAF began implementing BMPs in 2004 and com-	ing (2,232.4 ac).
pleted implementation in January 2017. BMPs imple-
mented to date include conservation crop rotation	A watershed implementation plan was developed
(328 sites; 1,117.4 acres [ac]), residue management	for Bayou Queue de Tortue in 2013. Bayou Queue
(344 sites; 6,008.2 ac), grade stabilization structures	de Tortue was made a priority in The Gulf of Mexico
(410 sites; 32 ac), irrigation land leveling (464 sites;	Initiative (GoMI). BMP implementation occurred in
4,638.72 ac), shallow water for wildlife (646 sites;	2012-2014- to improve ecosystem health in the Gulf of
Duson
Morse
Guevdan
Bayou Queue de Tortue Land Use
LDEQ Subsegment 050501
Developed	( )	Rice/Aquaculture
Forested Wetlands <"	Row Crop Agriculture
C 3 Grass/Pasture/Hay	Shrubland
C~ 1.) Herbaceous Wetlands	Upland Forest
Open Water	®	Ambient Monitoring

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Ambient Water Quality Network Data: TDS
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Figure 2. Irrigation land levelling in the Bayou Queue
de Tortue watershed.
Mexico, and also as part of the National Water Quality
Initiative (NWQI) starting in 2014.
After reviewing the BMPs implemented and their
purposes, LDEQ determined that the most effective
in reducing the TDS loads are the grade stabilization
structures (constructed between October 2013 and
September 2016) and the irrigation land leveling tech-
nique (implemented between April 2013 and March
2017) (Figure 2).
LDEQ and its partners began to see steady improve-
ment in the TDS levels in early 2016. LDEQ plans
to continue monitoring Improvements from BMP
implementation, and will use the information to apply
to future restoration efforts in other watersheds.
Results
As a result of BMP implementation, water quality has
improved, prompting LDEQ to remove TDS as a cause
of FWP impairment in the 2014 IR. The FWP use is
considered impaired if more than 30 percent of the
TDS samples for a reporting period (typically one year)
exceed 260 milligrams per liter (mg/L). The ambient
water quality network data in Figure 3 shows only one
TDS exceedance between May 2012 and September
2016, well below the 30 percent threshold.
In 2014 the TSS sedimentation/siltation and turbidity
impairment classifications were combined and listed
simply as turbidity. Although turbidity is still indicated
as a cause of impairment to FWP, the ambient and
monitoring data show a downward trend throughout
2016. Only two data points exceed 150 nephelometric
turbidity units (NTU), a criterion for FWP use support
Figure 3. Ambient Water Quality Network data for TDS
at site 0046 from January 2012 to September 2016.
in the Mermentau River (downstream of Bayou Queue
de Tortue). In the watershed implementation plan,
LDEQ predicted that the average turbidity would be
reduced to 149 NTU by 2016. The average of the 2016
monitoring data is 84 NTU. which is 44 percent better
than predicted!
Partners and Funding
DEQ spent a total of $108,350 of Clean Water Act
(CWA) section 319 funds on the Bayou Queue de
Tortue Project: $10,350 on laboratory analysis and
$98,000 on sampling staff and supplies. LDAF and
NRCS were instrumental in implementing BMPs in the
Bayou Queue de Tortue watershed. A total of 5,827.8
acres are currently under contract. The total payments
made in the Bayou Queue de Tortue CWA section 319
project from LDAF are $981,777.67 from 2013 to 2017.
The total match received is $1,337,336.58.
The conservation programs used to support the
goals and objectives of the GoMI are the USDA's
Environmental Quality Incentives Program (EQIP),
Conservation Stewardship Program, Wetlands Reserve
Program, Grasslands Reserve Program, and the Farm
and Ranch Lands Protection Program. This watershed
project receives EQIP funds which in some cases are
leveraged by funds from local and state partners. The
sign up for the Bayou Queue de Tortue 319 Project
occurred in February 2013. The Acadia and Vermilion
Soil and Water Conservation District boards set a cap
of $40,000 per contract with a maximum of one con-
tract per farm entity per parish. A total of 45 applica-
tions were received and 38 contracts were written for
a total of $1,059,967. The total amount allocated for
BMPs was $1,075,000.
U.S. Environmental Protection Agency
0** Office of Water
\ Washington, DC
. •if*	EPA 841-F-18-001E
^ pro^° February 2018
For additional information contact:
John Sheehan
Louisiana Department of Environmental Quality
225-219-0879 • John.Sheehan@la.gov

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