Stormwater Conference -Revitalizing an Impaired Lake: Hillside Lake East Fishkill NY

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Hillside Lake is a 26-acre, DEC-listed impaired lake surrounded by a residential community
of about 500 located in East Fishkill, NY. It suffers from a combination of stormwater runoff and the
drainage of unwanted nutrients into the lake from non- or low-functioning aging septic systems, causing
degradation of water quality over time.
These problems have compromised groundwater significantly and created crisis-level stormwater issues
during maximum weather events and resulted in the loss of a vital resource. Recent well reports from
homes near the lake show elevated levels of coliform and other hazardous pollutants. The lake that was
once the life force of a community is now shallow and unusable, covered with algae and other
unwanted plant blooms and has caused harm to the local ecosystem. The residents depend upon
aquifer-based resources for their drinking water. As in many communities that have been developed
around recreational assets, the lake and its inflow of suspended solids and phosphorus have influence
on this groundwater source. As goes the lake, so goes the water source. Preservation of water quality is
the key issue to the area’s sustainability
The Town was recently awarded a NYSDEC Water Quality Improvement Grant. A muti-faceted plan has
been developed and the first phases of the project are expected to go to construction this year.
The plan includes:
• Hydro raking of plants and vegetation in the lake
• Construction of an innovative gravel filter wetland filter to capture and treat at least 50
percent of the stormwater runoff
• Floating islands throughout the lake that will provide “in-lake treatment” and aeration,
• Constant recirculation of lake water back through treatment wetland filter from various critical
points in the lake
• Introduction of a unique Phosphorus media absorbent material
The system will remove 85 to 95 percent of the suspended solids and up to 50 percent of the
phosphorus loading into the lake, ultimately reversing the endemic deterioration of the lake’s water
quality and improving the natural ecosystem and protecting drinking water sources. In addition to water
quality improvement the project will provide flood resiliency and other provide eco-system and
economic benefits. This demonstration project illustrates how water bodies can be returned to health
using low-impact design practices. A future phase involves replacement of ageing and dysfunctional
septic systems with enhanced treatment units and other on-site natural mimicry treatments.
It is hoped that the presentation of this project, its treatment technologies and practices will provide
guidance for other communities with similar water quality problems in the Hudson Valley and elsewhere
in NY and around the world.
Beacon, NY
Distance Learning
Course Equivalency
Water / Stormwater Management
Health, Safety and Welfare
Learning Outcomes
1) Lake-specific water quality and stormwater issues
2) Treatment practices and effectiveness
3) Applicability regionally of the above
Steven Gruber (LEED Green Associate), Renewage David Whitney P.E., ECO-SOLUTIONS
Website Registration
Course Codes
New York Chapter of ASLA

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