ST. ALBANS — The Environmental Protection Agency (EPA) is preparing new pollution limits that will require the state to reduce the amount of phosphorous reaching Lake Champlain each year by 39 percent, or 188 metric tons.

Who will pay to clean up the lake and how large will those payments be? Those are the questions Vermonters will have to resolve in the next few months.

However, it is already being estimated that customers of stormwater treatment facilities could be forced to pay millions in new fees.

Vermonters will have to decide who will pay for the needed reductions and how, explained Dept. of Environmental Conservation (DEC) Commissioner David Mears on Thursday. Otherwise, the EPA will make those decisions.

“EPA is going to impose these costs on communities. The question is who pays and how is the money spent,” said Mears.

“There’s something in this for every body in terms of pain and responsibility,” said Eric Smeltzer, an environmental scientist with the Agency of Natural Resources (ANR). Smeltzer was in St. Albans Monday to speak to the board of the Friends of Northern Lake Champlain.

In 2010, EPA revoked its approval of Vermont’s phosphorous limits for Lake Champlain, known as the Total Maximum Daily Load (TMDL). “It’s an ultimate cap on the amount of phosphorous the lake can tolerate,” said Smeltzer.

Phosphorous encourages the growth of blue-green algae, which can be toxic to pets, hazardous to humans and disturbs the health of the overall ecosystem. State permits for stormwater and other discharges into Lake Champlain, including the permits for wastewater treatment facilities, are based upon the TMDL.

Absent a TMDL, both the renewal of existing permits and the issuing of new permits will be up in the air in the future. Without a valid stormwater permit properties can become difficult to sell.

The state is not in danger of losing its TMDL entirely. “One way or the other there will be a new TMDL,” said Mears.

The EPA is in the process of constructing that new TMDL. Although the limits themselves are based on science, embedded within the TMDL will be policy decisions about how the reductions will be achieved, according to Mears.

The TMDL is made up of three components:

• point source pollution from wastewater treatment facilities, large developments and other permit recipients;

• non-point source pollution from streambeds, agricultural lands, forests, local roads and any other unregulated stormwater discharges;

• a margin of safety.

Unless the state can assure the EPA that it will make the needed reductions in non-point sources, the EPA will demand greater phosphorous reductions from point sources, said Mears.

“One piece of it would necessarily be a focus on upgrading (wastewater treatment) plants to the highest level of technology possible,” said Mears. It is also likely municipalities would be required to purchase offsets for any remaining phosphorous discharges.

Upgrading the state’s wastewater facilities to achieve maximum possible phosphorous removal would cost millions. Upgrading the filters at the St. Albans City wastewater treatment facility alone would cost at least $2 million, Wayne Aldrich of Aldrich + Elliot reported earlier this year.

Such upgrades are “definitely not the best use of our dollars,” said Mears.

Large-scale developments most likely also would be held to more stringent stormwater discharge standards if the EPA is the agency enforcing the TMDL. “EPA’s tools are less flexible than the state’s,” said Mears. Any reduction efforts undertaken by EPA will be focused on permitted sources of phosphorous.

The state has the ability to require reductions from the non-point sources that scientists like Mary Watzin, of the University of Vermont, say are responsible for most of the phosphorous pollution. Those sources are many and vary across the watershed. For example, 52 percent of the phosphorous in St. Albans Bay is coming from cropland, according to scientists, while only 26 percent of the phosphorous in the Missisquoi River comes from cropland. [See accompanying graphic.]

Reaching phosphorous reduction targets will require addressing phosphorous from farms, developed lands, and stream erosion, Mears said.

“No sector gets off the hook here,” said Smeltzer.

Mears estimates $15 million to $20 million would have to be invested annually in lake cleanup efforts, although he said not all of it would need to be new money.

ANR is developing a plan to present to the Vermont Legislature in January and will hold a series of public meetings later this year to inform the public about what’s at stake and seek its input.

The new TMDL provides “an unprecedented opportunity for people to sit down at the table and develop practical, pragmatic solutions,” said Mears.

Everyone agrees on the importance of Lake Champlain to the state’s economy and the need to invest scarce dollars wisely, said Mears.

Asked about residents of eastern Vermont and their willingness to pay for Lake Champlain cleanup, Mears said that the Connecticut River and Lake Memphremagog have many of the same problems as Lake Champlain and any changes the state adopts would benefit those water bodies as well. The three watersheds combined cover 94 percent of the state.