EPA has defined seven reasons to remove an impaired water from the 303(d) list, as described below. When a waterbody satisfies any of these seven criteria as determined by the state, a request can be made to EPA to delist the pollutant-waterbody combination from the 303(d) list.
- The state determines water quality standards are being met.
- There was a flaw in the original 303(d) listing.
- Other pollution controls are expected to meet the water quality standard.
- The impairment is due to a condition other than a pollutant, e.g., a natural environmental condition or a condition not addressed by the total maximum daily load (TMDL) process.
- EPA has approved a TMDL and the listing was moved to Category 4A.
- The waterbody is not within the state's jurisdiction.
- Other reasons that are defined as needed.
Waterbodies with approved TMDLs are currently placed in Category 4A. Water bodies that are in 4A and now meet the designated use may be categorized in Category 2. It is important to note that water bodies and segments must be moved into Category 2 by designated use, not by pollutant. To qualify for Category 2, the water body would have to fully meet the designated use; if other pollutants were still causing an impairment for that use, the waterbody could not be moved into Category 2, instead it would be listed in both Categories 4A and 5.
Also, if a waterbody does support the designated use for which the TMDL was written and is moved into Category 2, the TMDL will always remain in effect for the pollutant(s) it addresses, unless superseded by a subsequent EPA-approved TMDL. However, while the TMDL will still apply to such delisted waters, they will be treated as a tier 2, or high quality, water requiring consideration of the water quality parameters that exceed the minimum required to support the base minimum for applicable designated uses during the Kentucky Pollutant Discharge Elimination System (KPDES) application and permit development processes. A review that results from the antidegredation policy is a benefit from the water quality perspective. Impaired waters that receive a KPDES permit are given water quality limits; those are developed to provide limits to protect the base minimum qualities of the applicable designated use.
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