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What's a TMDL?
Total Maximum Daily Load (TMDL) is
the amount of a particular pollutant that a particular stream, lake,
estuary or other waterbody can 'handle' without violating state water
quality standards. Of course, this is a greatly simplified
explanation! For details see our TMDL fact
sheet. So what's the big deal?
Once a TMDL is established, responsibility for reducing pollution among both point sources (pipes)
and diffuse sources is assigned. Diffuse "sources" include, but are not
limited to run-off (urban, agricultural, forestry, etc.), leaking underground storage tanks, unconfined aquifers, septic
systems, stream channel alteration, and damage to a riparian area.
Who's responsible for TMDLs?
Ultimately this responsibility lies
on the shoulders of everyone who lives works or plays in a watershed that
drains into an impaired waterbody. However, according the the Clean Water
Act, EPA is responsible ... if the states forgo their
responsibility. For your ease of use, we have collected and linked
state TMDL websites.
An overview of the TMDL process.
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Identify waters that do not meet water quality standards. In this process, the state
identifies the particular pollutant(s) causing the water not to meet standards.
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Prioritize waters that do not meet standards for TMDL development (for example, waters
with high naturally occurring "pollution" will fall to the bottom of the
list).
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Establish TMDLs (set the amount of pollutant that needs to be reduced and assign
responsibilities) for priority waters to meet state water quality standards. A separate
TMDL is set to address each pollutant with concentrations over the standards.
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Strategy to reduce pollution and assess
progress made during implementation of the strategy. This is when a watershed partnership
most likely will want to get involved. If the partnership has already developed a plan of
action, it should be shared with the state. In fact, several states have incorporated
watershed partnership plans in the state's strategy for specific TMDLs.
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