Photo Courtesy of Chesapeake Bay Foundation

Algae blooms, like this one in the Chesapeake Bay, are typically caused by high levels of nitrogen and phosphorus.

Environmental groups say a pair of lawsuits they have filed against the U.S. Environmental Protection Agency are necessary to reduce the size of large algae blooms, or "dead zones," that stretch for miles in the Gulf of Mexico, Chesapeake Bay and other waterways across the nation.

But the National Association of Clean Water Agencies (NACWA) says court rulings in the environmental groups' favor could have "astronomical" financial impacts on wastewater treatment agencies, which would face facilities upgrades to comply with the stringent new standards.

In lawsuits filed on March 13 in two federal district courts, the Natural Resources Defense Council (NRDC) and other environmental groups are seeking to force EPA to take tougher action to curb pollution, including nitrogen, phosphorus and other nutrients, in U.S. waterways.

One lawsuit challenges a 2011 EPA decision to leave the responsibility for setting numeric limits for nitrogen and phosphorus to the states, instead of issuing a nationwide federal standard for those states that have not developed such benchmarks.

The other lawsuit seeks to direct EPA to respond to a 2007 petition submitted by the groups. The petition asked EPA to add nutrient removal to current Clean Water Act secondary-treatment requirements.

EPA says it is in the process of reviewing the suits but has said previously that although nutrient pollution is a high priority, the agency does not believe a comprehensive rulemaking "is the most effective or practical means" of addressing these concerns.

NACWA is not a defendant in the lawsuits but is considering intervening in the cases, says Adam Krantz, NACWA's managing director of legislative and government affairs. "We're taking this very seriously," he says.

Krantz adds, "Depending on how this goes, [the ruling could] impact every single treatment plant across the country at a time when municipalities are dealing with an enormous economic downturn that's been lingering for years." According to NACWA, a technology-based treatment limit for every U.S. wastewater treatment plant could cost more than $280 billion in initial capital expenses.

Noting that not all waters are impaired by nutrients, Krantz says, "this notion of a one-size-fits-all technology standard for utilities doesn't make any sense, nor does it get at solving the problem."

Ann Alexander, a NRDC senior attorney, argues that an EPA review of the technologies available to deal with nutrients in the secondary-treatment process is long overdue. Alexander says the Clean Water Act requires EPA to review the secondary-treatment technologies "from time to time." EPA last reviewed such technologies and issued standards in 1985, she says.