Once set, officials would assign water quality criteria to each use. Ultimately, water quality managers will match up a particular designated use with the numeric criteria that will achieve that goal. For example, a shallow water habitat designated use intended to support underwater Bay grasses may have water clarity criteria that requires light to be able to penetrate to a specific depth so grasses can grow. An open water habitat designated use may have specific criteria for chlorophyll and dissolved oxygen. Once each of the designated uses is mapped and matched with new criteria, the Bay Program will crank up its computer models to determine the amount of nutrient and sediment reductions needed to achieve the new goals throughout the Bay.
Officials hope to accomplish that by the end of next year.
Then, the Bay states will formally adopt the new designated uses and criteria as their water quality standards. As that happens, the 40 percent nutrient reduction goal that has driven nutrient reduction efforts since 1987 will become moot. Officials fear TMDLs would be more costly and difficult to implement. Existing water quality standards don't do the job. At the same time, existing standards may overprotect other areas.