What we want to make sure is that we don't end up with water quality criteria and standards that are on the books, but ignored like the ones we have now. The new criteria, they say, will be the best natural conditions that could be attained given that large portions of the watershed have been irreversibly altered. In other words, the criteria reflect that the clock can only be turned back so far. And, while dissolved oxygen is not directly discharged and therefore can't be regulated in a permit, the model-derived nutrient loads needed to attain the dissolved oxygen standard can be placed in a permit, officials say. A lot of other areas aren't able to do that.
Officials offer a variety of reasons why phosphorus and nitrogen criteria pose problems.
Such variables as the ratio of nitrogen to phosphorus in the water, salinity, temperature and the forms of the nutrients that are available determine the amount of phytoplankton production. Therefore, a single set of nitrogen and phosphorus concentrations might not achieve the desired habitat goals, Batiuk said. Wastewater treatment plant operators in Virginia and Maryland also oppose setting standards based on nitrogen and phosphorus concentrations in the water. Because they are so easily translated into permit limits, they fear that wastewater treatment plants will be targeted for a disproportionate amount of nutrient reductions, regardless of the cost. They view the allocation of nutrient loads among different sources of pollution as a more equitable way to make reductions.