The Bay Program has a new message for dischargers across the watershed: Dilution is no longer an acceptable solution to pollution, at least when it comes to potentially harmful chemicals.

On October, it approved a new strategy aimed at convincing industries and wastewater treatment plants to voluntarily phase out “mixing zones” by 2010. Almost everyone agrees the goal, part of the Chesapeake 2000 Agreement, will be a hard sell.

“It’s not going to save them money,” said Bob Steidel, of the Hopewell Regional Wastewater Treatment Facility in Virginia, who co-chaired the Bay Program group that wrote the strategy. “It is going to cost them money initially.”

Mixing zones are areas beyond the end of a discharge pipe where chemicals are allowed to exceed water quality standards while they are diluted in the water. They are legal under the Clean Water Act, and are supposed to be designed in a way that minimizes impacts on aquatic life.

Still, there are worries that certain chemicals, even in small quantities, may pose long-term hazards because they can build up in sediments, or bioaccumulate in the food chain. As a result, mixing zones have become more controversial, and environmental groups have urged an end to their use in the Bay watershed.

“This is focused on a specific group of bad chemicals and an archaic pollution control technique,” said Kim Coble, of the Chesapeake Bay Foundation, who participated in the group developing the strategy. “I think this is one of the first real tests of how effective a voluntary strategy will be. I really hope we are successful.”

The Chesapeake 2000 Agreement called for eventually achieving a “zero release” of chemical contaminants into the Bay. While there is no timetable to meet that goal, the agreement set a near-term goal of phasing out mixing zones for persistent or bioaccumulative toxics by the end of the decade.

“You can only get to zero release when everyone meets water quality at the end of the pipe,” Steidel said. “So the logical first step would be to voluntarily eliminate mixing zones.” Mixing zones have become increasingly controversial — some environmental groups refer to them as legal “killing zones” — and the EPA last year issued final regulations to phase out mixing zones for 22 toxic chemicals in the Great Lakes basin.

The Bay Program approach is dramatically different from that in the Great Lakes. The Great Lakes ban affects 22 chemicals, some of which — such as DDT and chlordane — are already banned. Also, the Great Lakes rule applies only to chemicals that bioaccumulate in the food chain.

The Bay Program’s phase-out strategy covers not only chemicals that bioaccumulate, but also those that persist in the environment, such as toxic metals. It initially covers 13 substances, but will be expanded in the future. “Chemicals will be added as new data become available to justify their inclusion on the list,” the strategy says.

The biggest difference, though, is that the Bay Program is hoping to achieve its goal voluntarily, rather than through regulation. By giving dischargers a long lead time, and potentially providing various incentives, officials hope industries and wastewater treatment plants will move forward on their own — something that offers more flexibility about how the goal is met than a regulation would.

“Nobody has ever asked for this voluntarily before,” Steidel said. “The Great Lakes program mandated it through regulation. The Bay Program has always been pretty much on the cutting edge of trying to do new things, and this is a new thing.”

In the Great Lakes, the EPA’s regulations affected about 300 facilities. When fully implemented, the regulations are expected to eliminate discharges of about 700,000 pounds of chemicals a year. The EPA estimated the regulations would cost about $12 million to $35 million annually.

So far, comparable figures for the Bay watershed on the number of facilities affected, the amount of chemical discharges reduced and the cost of the program, are not available.

In part, that’s because the strategy lays out a phased approach to reaching the goal. Initially, it focuses on facilities in the Bay’s three “Regions of Concern” — the Anacostia and Elizabeth rivers, and Baltimore Harbor — which are known to have contamination problems, as well as 10 tidal river areas, known as “areas of emphasis” which are suspected of having toxic contamination problems. Virginia and Maryland officials estimate a few dozen facilities in those areas will initially be affected. Eventually, the phase-out will spread throughout the watershed.

The mixing zone phase-out ultimately calls for meeting water quality standards “at the point of discharge.” Some facilities don’t actually have mixing zones delineated, but are allowed to exceed water quality standards at the end of their pipe because some amount of mixing is figured into their permit. In Virginia, for example, some degree of dilution is automatically factored into permits for discharges into tidal areas. In Pennsylvania, there are no mixing zones but the state has “effluent compliance time areas” which allow dilution after discharge.

“Some places don’t have regulated mixing zones per se,” said Mark Richards, of the Virginia Department of Environmental Quality, who helped to develop the strategy. “But the bottom line of the strategy is the water quality standard has to be met at the end of the pipe.”

Eventually, the number of facilities affected by the strategy, either because they have mixing zones, or because they do not currently meet water quality standards at the end of the pipe, will likely number in the hundreds.

Steidel said no one should have illusions that selling the idea will be easy. Industries must request a mixing zone — a process that can be contentious — usually for economic purposes. Also, many facilities rely on mixing zones to offer them a margin of safety in their discharges to prevent permit violations — and potential fines. Getting rid of mixing zones, therefore, may not only cost money, but expose a discharger to penalties.

“Someone made a decision to ask for that mixing zone because they are not easy to get,” Steidel said. “So we are challenged to convince the same people who probably went through an intensive internal debate over whether to ask for a mixing zone, to give it up.”

Another compounding factor, officials say, is the likelihood that water quality standards for some contaminants will be strengthened over time. As allowable pollutant concentrations are reduced, facilities are more likely to want mixing zones to help avoid permit violations.

“The water quality standards get stricter over time, so we may be facing a moving target,” said Ed Stone, of the Maryland Department of the Environment, who was on the task force that wrote the strategy. “It is going to be very challenging.”

Publicly owned wastewater treatment plants may face particular hurdles. Many receive discharges from industries, so plant operators may need to persuade multiple companies to reduce wastes in order to phase out a mixing zone.

In addition, treatment plants may need to develop educational campaigns that encourage homeowners to abandon products that might release small quantities of harmful chemicals. And wastewater treatment plant operators may be reluctant to make the politically difficult action of raising costs to ratepayers to eliminate mixing zones.

Jim Pletl, environmental scientist with the Hampton Roads Sanitation District in Virginia, cautioned that too much emphasis on getting rid of mixing zones could result in a lot of money being spent to reduce a small amount of chemicals with limited risk, rather than addressing bigger water quality issues.

“We need to focus on the places where mixing zones are causing environmental problems,” he said. “If you have a persistent chemical like copper that is not causing a problem environmentally, it may cost money to eliminate that mixing zone for copper that could be spent on something that is really causing a problem.”

To sell the phase-out concept, the strategy envisions having teams visit facilities to try to persuade operators to give up their mixing zones. The teams would likely include state and federal officials as well as representatives from industry and public wastewater treatment plants who have made significant chemical reductions through pollution prevention.

The study calls for contacting all facilities in the initial focus areas by the end of next year.

To help make the sale, the strategy calls for working with facilities to provide technical assistance and incentives to those willing to eliminate mixing zones. One possible incentive could be giving plants potentially cost-saving flexibility in how they meet environmental regulations. The strategy also calls for giving facilities that eliminate mixing zones public recognition.

Lurking in the background though, is the potential that future federal regulations may eventually further restrict the mixing zones — something that has been discussed in the past.

“That’s where we may have some good explanations as to why they should consider it now,” Steidel said. “If they are ahead of the curve and it does become mandatory, they’ve already done it and they’ve gotten some regulatory relief for it, they can keep that regulatory relief.”

The Maryland Department of the Environment is already planning to incorporate some of the language into new permits to begin alerting dischargers. As permits come up for renewal, the agency is asking that dischargers submit a long-term plan about how they may work toward the goal. “There is no real teeth there, but it is an attention-getter,” Stone said.

Officials who wrote the strategy described it as a “living document” that will be revised over time to include new, effective ways to phase out mixing zones, as well as new information about toxic chemicals.

But they acknowledge that the first edition of the strategy leaves some key questions unanswered.

For example, it’s not clear whether facilities must have mixing zones removed from their permits — or just not use them — to comply with the strategy. It may be easier to phase out the use of mixing zones, officials say, than actually get rid of the zones themselves because facilities will likely want to keep them as a margin of safety against potentially costly permit violations.

It’s also unclear what happens with new mixing zones. The strategy does not prohibit new ones from being permitted, nor does not say what states should do about future requests for mixing zones.

Coble, of the CBF, expressed concern that if new mixing zones are allowed while others are phased out, the Bay Program would find itself “taking two steps forward and one step back.”

“Overall, I’m very impressed with the strategy,” she said. “But that’s one area that we need to take a hard look at.”

Steidel said state regulations allow anyone to ask for mixing zones, and agencies cannot reject mixing zones outright. “You can’t say no,” he said. “All you can do is educate them prior to their submitting a mixing zone request. But I think any new ones will have a higher level of scrutiny from the state.”

A copy of the report, “Voluntary Mixing Zone Phase Out Strategy” can be found at: www.chesapeakebay.net