Watershed decision puts first-ever numeric limits on toxicity in LA's water

jc-mg-200-names.jpgMark Gold writes: Last week, the Los Angeles Regional Water Quality Control Board approved discharge permits for two Los Angeles County Sanitation District water recycling plants. That's not news. The regional board approves discharge permits for industries and sewage treatment plants nearly every month. But these permits were different because they contained enforceable, numeric limits for toxicity to aquatic life--a first for sewage treatment plants in California.

Currently, there are approximately 80,000 chemicals that are commonly used in the United States. And every year, more than a thousand new chemicals come on the market. Despite all of these chemicals now being used in our daily lives, our system for regulating water quality is still based on 126 priority pollutants under the Clean Water Act. That means that there are tens of thousands of potentially toxic chemicals that are essentially unregulated under the Clean Water Act. Chemicals such as perchlorate, pyrethroids and dozens of other pesticides, MTBE, and hundreds of pharmaceuticals aren't regularly monitored or regulated in industrial, sewage, and urban runoff discharges to our waterways and beaches. As you can imagine, many of these chemicals are toxic to aquatic life, even at the parts per billion level.

Ceriodaphnia dubia.jpgOne of the safety nets in water quality permits is a requirement that polluters can't discharge toxic chemicals in toxic amounts. Currently, for plants that treat municipal waste, these limits are in a narrative form: "no discharge of pollutants in amounts toxic to aquatic life." This significantly limits the scope of measuring compliance and ensuring meaningful enforcement. As a result, the state of California's record on enforcing toxicity requirements has been dismal. Permit requirements are limited to using water quality triggers to identify the source of toxicity in effluent and come up with a plan to reduce toxicity when effluent is found to cause acute toxic effects (usually death) or chronic effects (such as limiting growth or reproduction) in fish, invertebrates, or other aquatic organisms. But even these toxicity identification and reduction requirements are rarely enforced by the regional boards that approve water quality permits. The new limits are based on the U.S. Environmental Protection Agency's approved "test for significant toxicity," and they include a single daily maximum and a monthly median limit for toxicity to fathead minnows, a water flea named Ceriodaphnia dubia (pictured above), and Selenastrum capricornutum, a green alga

The California debate on permit numeric limits for toxicity has been raging since the state Water Resources Control Board overruled a move by the Los Angeles Regional Water Quality Control Board in 2003 to put numeric limits in a discharge permit for the Whittier Narrows water reclamation plant. Since then, the state water board has said that establishing a numeric toxicity policy was a top priority, and the board even released a number of draft policies. But despite strong support for numeric toxicity limits from Heal the Bay, the EPA regional office, and the LA regional water board, the state water board has yet to release a final toxicity policy. As a result, dischargers in California have received permits without numeric toxicity limits for the last 11 years.

Last week, the LA regional water board decided that it wasn't going to wait anymore. In a bold and precedent setting move, board members unanimously approved discharge permits for the Whittier Narrows and Pomona water recycling plants that contain numeric rather than just narrative chronic toxicity limits. The new permits establish daily maximum and monthly median toxicity limits using rigorous scientific testing of the water that comes out of the treatment plants compared to clean water. Living organisms--fathead minnows, water fleas, and green alga--are placed in diluted treatment plant effluent and monitored for toxicological effects including larval survival, fecundity, and growth to determine if the effluent passes muster (minimal to no toxicity) or fails (if 25 percent or more of the organisms in the effluent samples suffer an adverse effect compared to those in clean water samples).

So what happens next? The Los Angeles County Sanitation District is likely to appeal the permit decisions to the state water board. But the larger scale impacts of this decision are still unclear. And they could be profound. Will this move lead to the state water board finalizing a long overdue toxicity policy? From now on, will all of the discharge permits issued by the LA region's water boards, including stormwater permits, contain numeric chronic toxicity limits? If so, protections for aquatic life will improve markedly in Los Angeles area waterways and perhaps even statewide. And one of the most glaring holes in water quality regulation will finally be patched.

Photo of Ceriodaphnia dubia courtesy of the Biodiversity Institute of Ontario.

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