“Don’t tell us how to restore clean water in our backyard,” says the Chesapeake Bay Foundation in a response to attorney generals from 21 states, who last week joined the battle to stop an epic cleanup effort under way on Chesapeake Bay. But why would anyone argue against cleaning up the Bay? Well, it’s not cleaning up the Bay that these attorney generals have a problem with, per se, it’s the way the Environmental Protection Agency (EPA) is dictating how states accomplish that goal. Add in a large farming lobby and things get interesting pretty quickly.

Okay, a little science first, because it’s necessary to understand the issue. Unlike what many may think, it isn’t toxic chemicals such as PCBs, mercury, and other nasty sounding mixtures that are killing the Chesapeake Bay (although they obviously contribute). The real culprits behind the Chesapeake Bay’s decline are the billions of tons of nitrates and phosphates that get washed into the Bay every time it rains, or when one of the Bay watershed’s 17 million residents flush a toilet.

Nitrates and phosphates can be found in common household items such as dish detergent and lawn fertilizer to farm products and byproducts such as chicken manure and industrial fertilizers. Another huge contributor to the nitrogen and phosphorous problem is sewage, since even much of the treated effluent that makes its way into the Bay still contains these nutrients.

Once they get into the water, they these nutrients wreak havoc. Nitrogen and phosphorous are basically plant food, and when they get washed into a body of water, they cause the algae there to bloom in exponential numbers. When the algae die, and then decompose, that natural process sucks the oxygen out of the water, which in turn kills crabs, fish, and oysters. You might have heard the term “dead zone;” it is an area with little or no dissolved oxygen in the water, and they are almost always caused by nutrient pollution. Scientists wondered for years how to even start fixing a problem of this scale. And then the government stepped in.

In 2009, President Obama issued an executive order to clean up the Chesapeake Bay. That’s when the EPA proposed putting the Bay on a “pollution diet,” and required the Bay watershed states of New York, Pennsylvania, Delaware, Maryland, West Virginia, Virginia, and the District of Columbia to submit plans on how they intended to reduce runoff. This included limiting what’s called the “Total Maximum Daily Load for Nitrogen, Phosphorous, and Sediment,” or TMDL for short.

States submitted plans for upgrading sewage treatment plants and reducing storm water runoff. To pay for many of these enhancements, municipalities started adding “Bay Cleanup” and “Stormwater Utility” fees to folk’s water bills. It’s popularly known as the “rain tax.”

But the EPA’s plans also included placing strict regulations on farmers—primarily on how they keep animal waste and fertilizer from entering the water from their land. Unsurprisingly, the American Farm Bureau Federation filed suit, and was quickly joined by the Fertilizer Institute, National Pork Producers Council, and the National Chicken Council. The effort failed, and the decision went to appeal. That’s where all of those attorney generals come in. Just last week they filed an amicus brief to support the American Farm Bureau Federation’s appeal.

The attorney generals say that allowing the EPA to manage how Chesapeake Watershed states comply with the regulations is a federal overstep, and will ultimately affect how their own states (many of which are in the Mississippi River watershed) comply with federal Clean Water Act regulations. Their brief argues that the EPA’s Chesapeake Bay TDML “strips states of their traditional right to make the land-use decisions necessary to comply with federal water quality standards,” adding, “Instead of setting the aggregate amount of certain pollutants allowed in impaired waters, the Environmental Protection Agency (EPA) used the Chesapeake Bay TMDL to micromanage sources of pollution that by tradition—and by statute—have been beyond EPA’s reach.”

Decisions in this case could have far-reaching effects on how future waterway restoration efforts—especially those supported with federal funds—are carried out in the United States. An expected decision date for the appeal was not available at the time this story was being written. Stay tuned for more details when they emerge.