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How are TMDLs Managed?
Because TMDLs are based on federal law (Section 303 (d) of the CWA),
the U.S. Environmental Protection Agency has primary responsibility for their
administration. However, US EPA generally
delegates this responsibility to the state or tribal department
charged with protecting environmental
quality, while maintaining oversight of the process. The state or
tribal environmental
agency then becomes responsible for compiling the 303(d) list and
delivering it to the US EPA in
a timely fashion.
The state or tribal environmental agency may further delegate the
responsibility for implementing, monitoring, and developing research related to TMDLs to environmental
arms of other state and local agencies and tribes such as state departments of forestry,
agriculture, or local utilities and conservation districts. These agencies may become Designated
Management Agencies (DMAs) responsible for the day-to-day decisions in the watershed
required to implement TMDLs. DMAs may be required to prepare monitoring and BMP related
plans, which require approval by the state or tribal department in charge. They can be
held accountable for reporting
the results of their monitoring and BMP implementation activities.
Additional groups of concerned citizens, scientists, and engineers may comprise watershed councils and technical advisory committees, either by invitation of
the state environmental agency or DMAs, or through grassroots organizations. While lending
considerable credibility and stakeholder involvement to the process, watershed councils and
technical advisory committees
rarely have any legal status in the TMDL process.
Because the longest-standing TMDLs in the nation are just a decade
old, it is still too soon to discuss typical time frames for the TMDL process from start to
finish. TMDLs can require years to generate and implement. First, all available water quality data
needs to be reviewed and analyzed. Additional data may need to be collected. Understanding
enough about a particular problem to assign a load or to even pinpoint the pollutant source(s)
can take years. So can the process of allocating loads.
Of course, once a model for TMDL development has been established,
the process may be used to expedite similar TMDLs. But watersheds are like human
fingerprints: no two are identical.
Due to the variations in watersheds, investigative patterns may be
duplicated from one watershed to the next, but the "cookie cutter" approach will never be
successful. Some watersheds aremainly agricultural, some are urban, some are heavily forested, some
are dominated by industry –and most are a mixture of these land uses. Even watersheds that are
predominantly of one landuse type can have great variety: for instance, there can be great
variety in groundwater inputs due to variations in hydrology in different sections of the watershed.
Basic geology can result in differences in background chemistry and loads. Different soils in the
same watershed may have much different erosion potentials.
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