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Is Cayuga Lake an "Impaired Waterbody"?
Bill Foster
Watershed Educator
As debate over the state of the lake continues in local papers
and between concerned organizations and individuals, it’s
easy to become overwhelmed with unfamiliar terms and figures.
In this article and others to follow, the Network will attempt
to keep its readership up to speed on the issue in language
that won’t require a PhD to understand. Please let us
know if we’re accomplishing that goal!
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What is a TMDL?
Simply put, the Total Maximum Daily Loads
that may be created for Cayuga Lake will calculate how
much phosphorus or sediment can be input into the lake
and its tributaries before adverse effects begin to
occur. However, in order to make these calculations
meaningful, the State must assess all contaminant sources,
and evaluate the relative impact of each source. For
example, phosphorus entering the system from farm activities
along Fall Creek would likely have a much different
impact than phosphorus entering the lake directly from
a wastewater treatment plant. Once pollution sources
and processes are modeled, calculations can be made
to determine how much each source must be reduced in
order to mitigate impairments in the Lake. The results
of this process would then be used to develop a TMDL
implementation plan in collaboration with stakeholders.
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To begin, the Federal Clean Water Act requires states to
periodically report on the quality of their waters. Section
303(d) of that Act also requires states to identify waters
that appear to be "impaired", because they cannot
be used for appropriate activities, or "designated uses".
These waters are then included in a biennial 303(d) listing,
and if it is appropriate, the state must characterize pollution
sources and calculate the level of reductions necessary to
mitigate specific impairments. This process results in the
calculation of a Total Maximum Daily Load, or TMDL.
Why Is Cayuga Lake Considered to be Impaired?
The "designated uses"for Cayuga Lake include bathing,
recreation, and drinking water supply. NYS Department of Environmental
Conservation (DEC) believes that the continuing closure of
the bathing beach that once existed at Stewart Park, coupled
with aesthetic complaints and a growing water quality database,
provides adequate evidence that the southern portion of the
Lake is not supporting its designated uses. Because of this
impairment, DEC identified southern Cayuga Lake as a candidate
for TMDL development on its 2002 New York State Section 303(d)
List of Impaired Waters, recently submitted to EPA.
Water clarity is complicated within the southern portion
of the lake due to a combination of factors. Tributaries carry
sediment to the lake and lake bottom sediment is stirred up
and resuspended as a result of high winds and waves. Both
types of sediment may carry phosphorus particles. Phosphorus
is a limiting nutrient meaning the growth of aquatic plants,
including algae, increases when more phosphorus is available.
Algal growth can have a significant effect on water clarity
and perceived water quality.
What Happens Now?
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Where does the DEC Stand?
DEC is required by federal law to move
forward with TMDL preparations for phosphorus and sediment.
However, final development of TMDLs for the southern
end of Cayuga Lake is a ways down the road. According
to Cliff Callinan, a DEC engineer who has been studying
Cayuga Lake during the past several years, "The
use impairment issues within the southern portion of
Cayuga Lake are complex, and the potential resolution
of these issues will require substantial additional
study of the south lake and tributary system. While
plans are not yet final, the effort will likely entail
several additional years of water quality monitoring
and model development. These activities are necessary
to further define pollutant sources and system dynamics
that will form the basis for TMDL development."
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The lake’s impairments are characterized largely as
the result of turbidity and sediment. DEC notes in its findings,
however, the need to better understand these closely related
water quality concerns. To that end, it is likely that DEC
will seek a comprehensive study of contributing factors —
particularly sediment and phosphorus sources — over the
next few years. While there is a common assumption that TMDLs
will be required for phosphorus and sediments, it is important
to understand that alternative solutions may arise as more
information emerges. Further, EPA has established criteria
intended to ensure that any steps eventually prescribed to
reduce pollution levels targeted by a TMDL will be the result
of a collaborative planning process between DEC and watershed
stakeholders. In the case of Cayuga Lake, the extensive effort
invested in the creation of the Cayuga Lake Watershed Restoration
and Protection Plan should provide an excellent starting
point.
Given the complexity and potential impact of the TMDL process,
it is important that watershed communities interact effectively
with DEC to ensure that conclusions reached are accurate,
and that eventual pollution reduction goals are realistic.
DEC maintains that public input is valued, and has already
responded to nearly 30 comments submitted regarding Cayuga
Lake’s 303(d) status. Readers may view responses and
additional information on DEC’s website, at www.dec.state.ny.us/website/dow
or may contact the Network for information.
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