Imagine, for a moment, that you are a blade of underwater grass stuck 3 feet deep in a salty portion of the Chesapeake Bay.

Like a seedling trying to survive in the middle of a forest, you would want as much sunlight as possible to keep from withering away. But in your case, algae and sediment floating overhead keep hogging the light.

To survive, years of research suggest, you would want the water to be clear enough for at least 15 percent of the sunlight that strikes the surface to reach you.

Otherwise, like nearly 90 percent of the “submerged aquatic vegetation” that once existed in a cleaner Chesapeake, you would become a grass of the past.

Similarly, if you were a fish swimming through much of the upper layers of the Bay, you would want at least 5 milligrams per liter — roughly five parts per million — of oxygen in the water to keep from literally turning belly up.

If you were a clam living in deeper parts of the Bay, you might be satisfied with 3 mg/l of oxygen. And if you were a lowly worm, living in the deepest part of the Bay, you would likely be thankful for 1 mg/l of oxygen, because often there is none.

Some of those numbers have been around for years. But now, the Bay Program wants to firmly link those habitat conditions with enforceable water quality standards. Ultimately, officials intend to set new nutrient and sediment reduction goals that will achieve those habitat objectives. These would replace current nutrient reduction goals, which are aimed more at general water quality improvements than at achieving a specific outcome.

“This is getting at what we mean by a restored Chesapeake,” said Rich Batiuk, associate director for science with the EPA’s Bay Program Office, who has been working on developing the new criteria.

The Bay Program recently got the go-ahead from EPA’s Washington headquarters to begin moving toward developing a water quality criteria for dissolved oxygen, water clarity and chlorophyll (a measure of algae) which are based on the needs of key Chesapeake resources, such as underwater grasses.

Eventually, probably around 2003, those goals would be adopted by states as water quality standards. Attaining those goals — like 15 percent light penetration at depths of 3 feet — will eventually help to determine what is a “clean” Chesapeake.

Once those standards, or goals, are attained, the Bay could be removed from the EPA’s list of “impaired” waters. If the Bay is still on that list in 2011, state officials fear that a potentially costly regulatory cleanup strategy, known as a TMDL — or Total Maximum Daily Load — would have to be developed for the Chesapeake.

The proposed Chesapeake 2000 agreement calls for cleaning the Bay by 2010 to prevent that from happening.

The EPA’s approval, stemming from a December meeting with Bay Program staff and state officials, also allows the Bay Program to pursue the new criteria as a possible alternative to the nitrogen and phosphorus criteria the EPA is developing nationwide.

Excess nutrients, largely from runoff but also from wastewater treatment plants, is seen as one of the major pollution problems for waterways across the country. To address the issue, the agency wants states to adopt its new nitrogen and phosphorus criteria — when developed — as water quality standards.

But officials from the Bay region contend that the EPA’s nutrient criteria may not clean up the Bay as well as resource-oriented criteria.

“In some parts of the country, maybe that’s where they should start with the process,” said Robert Summers, director of the Technical and Regulatory Services Administration of the Maryland Department of the Environment. “But we’re way beyond that in the Bay. We’ve got the ability to look at nutrient effects directly on living resources.”

Indeed, Batiuk argues, nutrients themselves usually are not the problem in water; certain amounts of them are critical for aquatic life. Rather, nutrients are the cause of other problems. They stimulate algae blooms, which block sunlight from reaching important underwater plants and rob the water of oxygen needed by fish and bottom dwellers.

Therefore, the Bay Program wants criteria based on maintaining healthy habitat conditions. It then proposes to use computer models to “translate” — tributary by tributary — those conditions into maximum allowable loads of nitrogen, phosphorus and sediment.

Those reductions, which officials say will be enforceable, would then be allocated to animal feedlots, wastewater treatment plants, farms and other sources of pollution.

But not everyone is convinced. Mike Hirshfield, vice president for resource protection with the Chesapeake Bay Foundation, said he and other CBF scientists like the idea of basing criteria on habitat needs. But, they are concerned whether such criteria could be legally enforced if states fail to achieve needed nutrient reductions and the Chesapeake remains on the “impaired” water list.

Normally, the EPA sets water criteria based on the best available science, which establishes the maximum allowable concentration of a substance that can be present in the water without harming human or aquatic life.

That concentration can be translated directly into the permit of a wastewater treatment plant or other discharger. Replacing nitrogen and phosphorus concentrations with habitat-based endpoints adds another “link in the chain,” Hirshfield said.

That link relies on models to translate those criteria into nutrient loads which must then be assigned to different pollution sources. Each of those extra links in the chain, Hirshfield said, may open the door for court challenges if the EPA or others were to seek permit limits for nitrogen and phosphorus. “The appeal of in-stream or in-Bay nitrogen and phosphorus values is the relatively short chain link to sources of nitrogen and phosphorus,” he said.

Further, he noted, states already have dissolved oxygen standards, but they are not often met in the Bay. “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.”

Bay Program officials contend that existing standards are not met because they are not attainable — even in a “pristine” Chesapeake, Virginia and Maryland portions of the Bay will likely exceed their current dissolved oxygen standards. 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.

“It may add an extra link in the chain, but it’s a much stronger link than they would otherwise have to rely upon to remove water quality impairments, so it’s a link worth forging,” said Bill Matuszeski, director of the EPA’s Bay Program Office in Annapolis.

“We’ve got the kinds of information that allow us to go into a more direct relationship with the living resources,” Matuszeski said. “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.

But, he said, setting overall reduction goals for an entire river — based on the impacts to water clarity, dissolved oxygen and chlorophyll — should prove to be more technically defensible in court.

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.

Others agree. While concentrations can be assigned to sources like wastewater treatment plants, they would be meaningless to sources such as farm runoff. Runoff reduction goals, they say, have to be set in pounds, not concentrations.

Still, Hirshfield said, the use of concentrations and loadings — at least to some degree — can be interchanged. He said he is concerned about the apparent decision to remove nitrogen and phosphorus from the decision-making table at the beginning of the criteria setting process, rather than at the end. The Bay Program, he said, should instead develop criteria for both nutrients and living resource endpoints.

Officials will be making final decisions in the coming year about exactly what set of criteria they will develop to define a “clean” Bay and serve as the basis for water quality standards. While many details remain to be worked out, they are optimistic the final standards will be more closely linked to needs of grasses, clams — even worms — than any used in the past. “This is a huge step forward,” Batiuk said.

Possible Criteria

The process of establishing criteria, or “clean Bay” endpoints, is just beginning. But attention is focusing on three areas that are closely linked to a healthy ecosystem and which have been studied for years in the Bay. Because of such studies, quantifiable measurements — or criteria — can be applied to each.

  • Chlorophyll a: Chlorophyll a is a direct measure of algae biomass, which forms the base of the Chesapeake Bay food web. Too much indicates a highly nutrient enriched system dominated by types of algae considered to be poor quality fish food. Chlorophyll a concentrations within certain ranges have been directly associated with balanced ecosystems containing phytoplankton assemblages representative of healthy aquatic systems.
  • Water clarity: Water clarity is critical to the survival and growth of Bay grasses, the vertical movements of zooplankton, and predator/prey relationships involving visual feeding. Research in the Bay has established the amount of light needed to penetrate the water in various parts of the Bay to allow grasses to grow.
  • Dissolved oxygen: Dissolved oxygen is a direct measure of habitat quality for a wide diversity of living resources, and is critical to survival, growth, reproduction and avoidance behavior. Previous work supported by the Bay Program established minimum levels of dissolved oxygen needed in different areas to support aquatic life.

Criteria & Standards

  • Water quality criteria describe the quality of water that will support a designated use, such as being fishable, or swimmable, and so on. The EPA publishes water quality criteria that reflect available scientific information on the maximum acceptable concentration levels of specific chemicals in water to protect aquatic life or human health.
  • Water quality standards are laws or regulations that states adopt to maintain water quality and to protect public health. They are the foundation for accomplishing the goals of the Clean Water Act.