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Real Science for Real People: What is a TMDL? By
Beth Ravit We have
now passed the 30th anniversary of the Clean Water Act. While there
has been notable success in eliminating point source pollution – direct
discharges into a water body from known sources – everyone acknowledges that to
meet the law as set forth in the Clean Water Act, we must now address pollution
coming from non-point sources. This is pollution that cannot be traced to a
specific site of discharge. Non-point source pollution is caused by lawn,
street, golf course and agriculture runoff, atmospheric deposition, or
subsurface water flow. Today in the United States an estimated 64% of
pollutants entering streams and 57% of pollutants entering lakes are from
non-point sources. Since the passage of the Clean Water Act, progress in
controlling non-point source pollution has been a notable failure. There are
currently 20,000 water bodies in the U.S. that do NOT meet the water quality
goals set by each State. In an effort to meet the
mandate of the Clean Water Act, EPA has joined with the States to establish a
“total maximum daily load” (TMDL) for each impaired water body. A TMDL should
represent the total maximum amount of a particular pollutant that a water body
can receive and still meet water quality standards. The amount of a pollutant
allowed under the TMDL program will be different for different categories of
water bodies. For example, a river designated “fishable and swimmable” or a
drinking water source will have a more stringent TMDL (lower value) than a
river not classified as “fishable and swimmable.” Setting
the TMDL is just the first step in improving water quality. Once the TMDL
establishes the total amount of a pollutant that can be received by a
particular water body, current sources of the pollutant must be identified and
a plan developed to reduce the pollutant to the level required by the TMDL.
This is obviously the more difficult step. New Jersey has 6 years left to
implement TMDLs for our surface water bodies (36 years after the passage of the
Clean Water Act). In September of this year, NJDEP Commissioner Bradley
Campbell committed NJ to establishing TMDLs on 159 stream segments by July,
2003. The first TMDL, already underway, is addressing fecal coliform bacteria
that indicate the presence of fecal material in surface waters. It is believed
that geese and dogs play a particularly important role in fecal contamination
of the upper Hackensack River. While the
TMDL process will hopefully do much to improve water quality in the upper
Hackensack River, it will not address combined sewer overflows (CSO) that
release fecal material into the lower River during storm events – a point
source of pollution. Combined sewer pipe systems, like those in Jersey City,
Hackensack, Ridgefield Park and North Bergen, direct rain runoff from municipal
streets into the sewer system, which then flows into the city’s sewage pump
systems. Under normal conditions, the pump station sends this combined water to
a local sewage treatment plant or to the regional Bergen County Utilities
Authority (BCUA). However, when it
rains, there is more incoming water than the plants were designed to handle, so
a portion of the water (containing raw sewage) is diverted from the city’s pump
station and released directly into the Hackensack River. While these municipalities
have tried to improve the outflow from their CSOs to meet EPA minimum
regulations, this is not enough to get the Hackensack River to “fishable and
swimmable” status. Captain Bill and Hackensack Riverkeeper continue to fight to
have the Hackensack River re-classified as “fishable and swimmable,” but to win
this fight, the fecal coliform levels that result from existing CSOs must be
eliminated. This means we must find the political will to deal with the large and
expensive fecal coliform issues. Unfortunately geese and dogs don’t vote. |