Agricultural
land cover and Residential land use
To further assess the impact of agricultural and
residential development on E. coli concentrations, the areal extent
of agricultural land cover and residential land use was calculated for
each site and compared to extremely high anomalous peaks in E. coli
concentration occurring at particular sites during 1998. Agricultural land cover was
calculated as percent agricultural area within a 100 foot stream buffer
within each drainage area. Residential land use was calculated as
building density within a 100 foot stream buffer within each drainage
area.
As indicated in the figure below, the highest density of
agricultural land cover is on the eastern side of the valley with sites
9, 10, 11, 13, and 14 having 19% or greater agricultural land cover
within a 100 foot buffer zone. The highest building densities are
associated with sites 1, 2, and 3 on the western side and 8 and 13 on
the eastern side. Sites 6 and 7 are forested with no agricultural
land cover nor buildings. Sites 13 and 14 are in Freeman Brook below and above
Warren village respectively. Although the area of agriculture is
nearly identical at both sites, building densities at site 13 (in Warren
village) are much higher than at site 14 (above Warren village).
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| Data and analysis by Deb Sargent under the direction of Dr. Leslie Morrissey, School of Natural Resources, University of Vermont. Cooperator: Friends of the Mad River. |
| E. coli concentrations for 8/25/98 differ considerably on the
western and eastern sides of the valley corresponding to major land
use categories. High E.
coli counts were observed on the eastern side of the valley except
at site 12 which has little agricultural land cover or human
development. Sites 9, 10, 11, 13, 14, and 15 have relatively high
percentages of agricultural land cover along with moderate building
densities. In contrast, E. coli concentrations are low on the western side of the valley
where percent
agricultural land cover is low, although some sites (1, 2, 3) have high
building densities. Sites 1,
2, 3, and 5 had low E. coli concentrations, similar to control sites 6 and 7. Site 8
also has a low percent agricultural land cover and high building
densities, but the E. coli concentrations are higher compared to
similar sites (1, 3) with low E. coli values. Site 8 drainage area includes part of Alpine
Village, a housing development built in the early 1970s.
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| Data and analysis by Deb Sargent under the direction of Dr. Leslie Morrissey, School of Natural Resources, University of Vermont. Cooperator: Friends of the Mad River. |
| E. coli concentrations at low flow, shown here on 8/19/98, are uniformly
low with only one violation of the current water quality standard (site
11). At low flows, no significant differences are apparent
between the eastern and western sides of the valley as was evident at
peak flow.
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| Data and analysis by Deb Sargent under the direction of Dr. Leslie Morrissey, School of Natural Resources, University of Vermont. Cooperator: Friends of the Mad River. |
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