Q
Section 319
NONPOINT SOURCE PROGRAM SUCCESS STORY
Verfnwt
Improved Agricultural Management Restores Stone Bridge Brook
Waterbody Improved
Nutrient and sediment runoff from agricultural sources
degraded the biological community in Vermont's Stone
Bridge Brook. As a result, Vermont placed a 2.0-mile segment of the stream on its
1998 Clean Water Act (CWA) section 303(d) list for aquatic life use impairments due
to agricultural impacts. Water quality improved after farmers implemented a variety of
agricultural best management practices (BMPs). Data collected in 2011 showed that
Stone Bridge Brook complied with state water quality standards, prompting the Vermont
Department of Environmental Conservation (VTDEC) to remove it from the CWA section
303(d) list of impaired waters in 2012.
Problem
Stone Bridge Brook (Figure 1), a 6-mile-long stream
in northwestern Vermont, flows through the towns of
Georgia and Milton and drains into Lake Champlain
south of St. Albans Bay. VTDEC classifies the stream
as a Class B water—a water that fully supports
aquatic biota and wildlife, high-quality aquatic habi
tat, good aesthetic value, swimming and recreation,
irrigation and agricultural uses, and public water
supply uses with filtration and disinfection.
VTDEC first assessed Stone Bridge Brook, just
above its confluence with Lake Champlain, in 1997.
VTDEC monitored macroinvertebrates in the stream
and assessed the biological integrity using a series
of eight biometrics, including the EPT (short for
the order names Ephemeroptera, Plecoptera and
Trichoptera) index—a measure of the number and
types of pollution-sensitive aquatic insects inhabit-
ing a waterbody. Streams showing high EPT rich-
ness (i.e., a high number of EPT taxa in a sample)
are less likely to be polluted than streams showing
low EPT richness in the same geographic region.
In addition, VTDEC used the Vermont Biotic Index
(Bl), which measures the proportion of organic
pollution-intolerant species to tolerant species
in a community (range: 0 to 10, where 0 = excel-
lent and 10 = poor). Among other measures,
VTDEC also assessed the abundance of a variety
of pollution-tolerant macroinvertebrates, includ-
ing the filamentous algae shredder Diptera
(Cricotopus spp.) and the filter feeding Trichoptera
l-igure 1. Stone Bridge Brook flows through
northwestern Vermont.
(Hydropsyche betteni). The presence of such
nutrient and sediment-tolerant macroinvertebrate
species can indicate poor water quality in streams.
Biological monitoring in 1997 found that the lowest
stream reach, which is 2.0 miles long, did not fully
meet Vermont's Class B water quality standards
for aquatic life. The segment had low EPT values
as well as modestly elevated Bl values, among
other indicators. These findings put the segment
in noncompliance with Vermont Class B water
quality standards for aquatic iife support. The state
suspected that nutrient and sediment runoff from
agricultural sources in the watershed contributed
to the aquatic life impairments. Vermont placed this
segment of the stream on its CWA section 303(d)
list of impaired waters in 1998.

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Project Highlights
The Vermont Agency of Agriculture, Food and
Markets (AAFM) and the VTDEC worked with farm-
ers in the watershed to address nonpoint source
pollution from agricultural areas. As a result of this
collaboration, farmers implemented a variety of
agricultural BMPs between 2010 and 2011, includ-
ing one roof runoff/clean water diversion, one
silage leachate collection and treatment system,
planting of more than 300 acres of winter cover
crops and use of no-till planting to reduce sedi-
ment runoff from agricultural fields. Additionally,
farmers developed and implemented nutrient
management plans covering 700 acres. Combined,
these actions helped to substantially reduce sedi-
ment and nutrient loading to Stone Bridge Brook.
Results
Data show that water quality has improved as a
result of the implemented BMPs. Biomonitoring
data from Stone Bridge Brook showed substantial
increases in EPT richness along with some mod-
est decreases in Vermont Bl scores between the
late 1990s and 2009-2011 (Table 1). The data also
show a substantial drop in the percent "shred
herb," the percent of algae-shredding organisms
that thrive in nutrient-rich conditions. A decrease in
the percent "shred herb" is a good indication that
filamentous algae have decreased as a food source
at the site. Although the 2009 EPT improvements
appear to pre-date much of the agricultural BMP
work in the watershed, the dramatic reduction in
algae-shredding organisms between 2009 and
2011 suggests that the waste management system
improvements and enhanced field practices in 2010
and early 2011 may have significantly improved
water quality. Stone Bridge Brook earned a rating
of "very good" and "very good-good" in 2009 and
2011, respectively, indicating that the stream com-
plies with Vermont's water quality standards. As a
result, VTDEC removed a 2.0-mile segment of Stone
Bridge Brook from the CWA section 303(d) list of
impaired waters in 2012. The stream is scheduled
for further biomonitoring in 2016.
Partners and Funding
The Vermont AAFM served as a key partner in this
effort, providing $102,977 in cost-share assistance
for agricultural field BMP implementation and
improvements to waste management systems.
Several farm producers and two local conserva-
tion districts also contributed to this work. VTDEC
conducted the biological and water quality monitor-
ing using approximately $4,000 in CWA section 319
funds. In addition, approximately $1,500 in CWA
section 319 funds supported the BMP design engi-
neering work conducted by the Vermont AAFM.
Table 1. Stone Bridge Brook Biomonitoring Results3 (1997-2011)
Sampling Site
Date
Assessment Rating
EPT
Index Score
Bl
(Biotic Index)
Percent Shred
Herbb
Mile 0.2
10/8/1997
Fair
12.0
4.74
6.7
10/12/1999
Good-Fair
14.5
4.20
4.3
9/29/2004
Good-Fair
14.0
4.15
6.9
10/9/2009
Very Good
21.0
4.02
7.0
9/22/2011
Very Good-Good
24.0
4.43
0.6
Warm Water Moderate Gradient Class B
Guideline
£16
<, 5.40
<, 5
8 Bold values indicate noncompliance.
b "Percent Shred Herb" refers to the percentage of filamentous algae shredders in the community.
£
<
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-12-001NN
September 2012
For additional information contact:
Eric Perkins, EPA Region 1
617-918-1602 • perkins.eric@epa.gov
Karen Bates, VT Department of Environmental Conservation
802-879-3229 • karen.bates@state.vt.us
Laura DiPietro, VT Agency of Agriculture, Food and Markets
802-828-1289 • laura.dipietro@state.vt.us

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