A filtration avoidance determination (FAD) issued by the EPA in 1997 allows New York City to not filter the drinking water from this system, but does require it to complete a final design for a filtration system that could be used if filtration were deemed necessary in the future.

The EPA is willing to drop the FAD requirement for a final filtration system design as long as the city completes its preliminary design, sticks to a strict schedule for upgrading sewage treatment plants that empty into the watershed, takes other watershed protection measures, and designs and builds a facility that would disinfect the Catskill/Delaware water using ultraviolet (UV) light.

In its request to the EPA for relief from having to complete the final design stages of a filtration system, the city's DEP said it would upgrade wastewater treatment facilities in the watershed that make up more than 83 percent of the area's wastewater flow by the end of next June. The wastewater treatment plant upgrades would remove waterborne pathogens and greatly reduce phosphorus discharges into local streams. The DEP will also complete a feasibility study on the use of UV light to disinfect Catskill/Delaware water, and will submit its findings to the EPA by December 31.

The EPA is seeking public comment on its proposal.