Current Updates
The plans for the first two BMP projects have been approved by Kentucky Division of Water. Click to download the plans for rain gardens or the Levi Jackson stormwater wetland.
In 2007, the Corbin City Reservoir Watershed Based Plan (WBP) was approved by the Kentucky Division of Water and the USEPA. Click Here to download. As of November 2007, Third Rock received notification that, in addition, our plan for implementing the WBP will be funded. This second phase of the project will begin in February 2008.
Background
None of the water quality problems that
exist in the Corbin City Reservoir watershed will be easily solved,
but we can achieve significant progress by prioritizing problems and
building community awareness. Many of the issues affecting our land
and water are highly interrelated. A watershed approach offers an
opportunity for comprehensive planning to better manage the
resources on which we all depend. The principle of a watershed
approach is to seek integrated solutions at a watershed level that
take into account all the land uses and needs of the community and
the environment.
Through a 2003-04 319(h) grant, Third Rock Consultants has identified and
quantified the pollutants negatively impacting the Corbin City
Reservoir and the tributaries within the watershed were quantified.
After thoroughly assessing and monitoring the watershed, the results
and recommendations for improving water quality were compiled in a
document for the Kentucky Division of Water. This document, or
Watershed Plan
indicates that failing sanitary sewers, stormwater runoff,
agricultural and construction activities, the London wastewater
treatment plant discharge, abandoned mine lands, and streambank
erosion are principal sources of pollutant to our water resources.
The Watershed Plan presents biological, chemical, and physical stream data,
locations where pollution control will be most beneficial, and a
plan for watershed-level remediation.
The Watershed Plan indicates that nutrient addition is the primary
source of the reservoir problem. Nutrients are entering the
waterways, and ultimately the reservoir, through the London
Wastewater Treatment Plant discharge (point source to Little Laurel
river via Whitley Branch), London’s stormwater runoff and suspected
sanitary sewer overflows (SSOs), exposed soil during construction
activities, cattle grazing, and other agricultural activities (nonpoint
sources). Measured phosphorus concentrations across the
watershed were often in the range where accelerated eutrophication
is likely for P-limited freshwaters. Elevated nitrogen
concentrations were also measured, especially at the station below
the wastewater treatment plant discharge.
Elevated total suspended solids (TSS) concentrations following storm
events indicate that overland sediment transport and/or
streambank erosion are contributing sediment to the streams.
Elevated phosphorus and iron levels correlate with the sediment
load. Based on personal communication with the director of the
Corbin City Utilities Commission (Herd 2006), sediment is indeed
accumulating and reducing the capacity of the Corbin City Reservoir.
Pathogen levels, from natural sources, cattle grazing,
failing septic systems, or SSOs, were elevated across the watershed.
Of the three major waterways draining the watershed, the Little
Laurel River contributed more to the nutrient, sediment, and
bacterial load entering the reservoir than the Laurel River and
Robinson Creek during all storm events measured.
The Watershed Plan also includes the physical stream character and potential
for biological support at 50 stream monitoring stations throughout
the watershed. This was determined using Rapid Bioassessment
Protocol (RBP) scores and measured pH, dissolved oxygen, and
conductivity. The RBP scores were consistently very low across the
entire watershed, and 41 of the 50 sites surveyed scored Not
Supporting. The other nine sites scored Partially Supporting.
Overall, the streams monitored consistently lacked adequate
riparian buffers, exhibited heavy sedimentation, and exhibited signs
of severe bank instability and degradation due to livestock.
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Poor Physical Habitat at
a Stream Monitoring Site |
Third Rock and Volunteers
sample a stream. |
Based on the level of impairment (as
indicated in the Watershed Plan), this watershed is in immense need of
watershed-scale remediation. In May 2006, Third Rock applied for
another 319(h) grant to fund projects and employ the remediation
solutions suggested by the Watershed Plan.
A holistic approach will be used to improve the water quality
throughout the entire watershed, targeting the most critical
areas in order to most efficiently and economically reduce
nonpoint source pollution. Likewise, it will be an iterative
approach, combining implementation projects and further study as
information becomes available.
A bioretention area or “rain garden” could be implemented to
capture, retain, and treat rooftop and parking lot runoff in a
developed area.
A bioretention area or “rain garden” can effectively treat
stormwater runoff in a rather inconspicuous way. The rain garden
has the capacity to treat and store runoff, but has the
appearance of an attractive landscape feature without using
large areas of land.
View of a rain garden adjacent to a parking lot.
A stormwater wetland could also be used to improve water quality
and reduce peak discharge. Like the rain garden, a
stormwater wetland offers passive, low-maintenance treatment of
nonpoint source pollution, as well as the aesthetic benefit of
unique habitat for vegetation, birds, animals, and aquatic life.
Like a natural wetland, a constructed wetland has the capacity
to capture runoff, releasing it slowly, and to improve the quality of
water passing through.
Stormwater wetland constructed to capture runoff
on a golf course in North Carolina.
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