Nonpoint Source Success Story Louisiana Implementing Conservation Practices in Boston Canal Reduces Turbidity Problem

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Implementing Conservation Practices in Boston Canal Reduces Turbidity

Waterbody Improved Sediment from agricultural runoff led to a turbidity impairment in

the Boston Canal (Subsegment 060910). The Louisiana Department
of Environmental Quality (LDEQ) determined the waterbody was not supporting its fish and wildlife
propagation (FWP) designated use because of high turbidity concentrations in its 2010 Clean Water
Act section 305(b) assessment. Beginning in 2013, LDEQ worked with the Louisiana Department of
Agriculture and Forestry (LDAF), the U.S. Department of Agriculture Natural Resources Conservation
Service, and the Vermilion Soil and Water Conservation District to address the impairment through
monitoring water quality, conducting outreach, and implementing best management practices
(BMPs). These efforts prevented the erosion and runoff of an estimated 3,000+ tons of soil; as a
result, in 2020, LDEQ removed the waterbody's turbidity impairment in the state's Clean Water Act
305(b) water quality assessment.

Problem

Boston Canal iies in southwestern Louisiana in the
Vermiiion-Teche River Basin. The basin contains one
12-digit hydrologic unit code (HUC-12) watershed,
080801030204. Of the approximately 16,000 acres
within the Boston Canal watershed, roughly 8,000
acres are classified as agricultural use; the remaining
acreage is coastal marshland (Figure 1).

Louisiana's water quality standard for turbidity states
that no more than 30% of the samples collected during
a sampling year can exceed the water quality standard
of 50 nephelometric turbidity units (NTU) per sample.
If more than 30% of the samples collected during a
sampling year exceed the standard, the waterbody is
considered impaired.

The state's 2010 assessment indicated the FWP use in
Boston Canal was impaired because of high sediment
loading and turbidity concentrations. The assessment
listed the suspected source of this sediment as agricul-
ture. Soil erosion in sugarcane production areas was
suspected to be contributing to the turbidity issues.

Boston Canal
Subsegment 060910
Land Use

Legend

Figure 1. Boston Canal is in southwest Louisiana.

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Story Highlights

Partners and Funding

From 2013 through 2018, partners worked in the
Boston Canal watershed to identify areas of high
sediment loading, conduct outreach to agricultural
producers, and garner participation in BMP imple-
mentation. LDAF initiated conservation plan sign-ups,
technical assistance, cost-sharing contracts, and BMP
execution through Clean Water Act section 319 fund-
ing. The Vermilion Soil and Water Conservation District
conducted on-site waste water system pump-outs.
The Natural Resources Conservation Service partici-
pated in agricultural BMP implementation through its
Environmental Quality Incentives Program funding.
BMPs implemented in the Boston Canal watershed
include over 3,600 acres of conservation crop rotation;
238 acres of cover crops; over 890,000 linear feet of
field borders; 1,800 acres of nutrient management;
48 on-site wastewater system pump outs; and 1,800
acres of pest management.

Results

Conservation practices implemented in the Boston
Canal watershed reduced the amount of soil eroding
and leaving the fields by 3,049 tons over the 2014-
2018 period (2014: 674 tons, 2015: 966 tons, 2016: 572
tons, 2017: 522 tons, and 2018: 315 tons). Turbidity
water quality criterion excursion rates also declined.

The 2020 water quality assessment was based on
monthly ambient monitoring in Boston Canal from
October 2017 through September 2018. Of the 12
sampling events, there was only one exceedance in
February 2018 (130 NTU). This 8% exceedance rate
fell below the 30% rate allowed by the water quality
criterion—and far below the 52% exceedance rate
found during the 2014-2015 water year. As a result of
this water quality improvement, LDEQ removed FWP
as a turbidity-impaired use in the Boston Canal in its
2020 assessment.

Partners responsible for making this project suc-
cessful included the U.S. Environmental Protection
Agency, the U.S. Department of Agriculture, LDEQ,
LDAF, and the Vermilion Soil and Water Conservation
District. Funding includes LDEQ Clean Water Act
Section 319 Program funds (federal: $260,550;
match: $173,700); LDAF section 319 project funds
(federal: $484,007; match: $408,971); and the Natural
Resources Conservation Service (federal: $108,164).
The total project cost for addressing the turbidity
in Boston Canal was $1,435,392 (federal: $852,721;
match: $582,671).

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U.S. Environmental Protection Agency
Office of Water
Washington, DC

EPA 841-F-24-001C
February 2024

For additional information contact:

Aimee Preau

LDEQ

225-219-3357 • aimee.preau@la.gov

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