ST. ALBANS — New Lake Champlain pollution limits being established by the federal government most likely will require changes to local ordinances, agricultural practices and require additional stormwater treatment within urban areas.

The landscape itself could change under measures designed to allow rivers and streams to meander within larger floodplains, and a permit process could be required for road projects.

The aim of all this is to a new and ambitious effort to remove phosphorous before it gets into the state’s waterways from agricultural lands, impervious surfaces such as roads and buildings, and erosion of the streambeds themselves.

The new Total Maximum Daily Load (TMDL) limits on phosphorus, as reported in Saturday’s Messenger, will not be released until next year.

However, the preliminary numbers show that the lake is receiving 317 more metric tons of phosphorous each year than it can handle. Vermont’s likely reduction target, under already discussed Environmental Protection Agency (EPA) limits, would be 188 tons.

To reach that goal, Vermonters would have to reduce the amount of phosphorous reaching the lake by 39 percent.

Divided over the various watersheds, Missisquoi Bay will need a 64 percent reduction and St. Albans Bay a 48 percent reduction.

In the Missisquoi River basin, stream bank erosion is the single largest source of phosphorous, at 41 percent.

“It’s not just about regulation. It’s about providing the ability to meet the new rules,” said Eric Smeltzer, an environmental scientist with the Agency of Natural Resources (ANR).

David Mears, commissioner of the Dept. of Environmental Conservation, estimates the state will need to spend $15 million to $20 million annually over the next 10 to 20 years.

“We’ve got to be brutally honest; we’ve got to be in this for the long haul,” said Smeltzer.

Since the devastation caused by Tropical Storm Irene a consensus has emerged at ANR that the state needs to change its approach to stream management.

Keeping development away from rivers and streams so that those streams can pool in floodplains and have room to meander is now considered the best way to prevent future floods and improve water quality over the long term, according to Mears.

That could mean changes to ordinances limiting development in flood plains and along stream banks. ANR has already begun advocating changes to local ordinances.

Some stream bank erosion is inevitable, but land uses can and do contribute to erosion, say state experts. Runoff from impervious surfaces, especially when it is collected and piped into streams, can accelerate erosion by increasing the volume and speed of water reaching the stream.

Similarly, when livestock is allowed to graze and wander alongside and into streams, it can destroy vegetation and expose the ground, making the shores of the stream more likely to erode.

In the St. Albans Bay watershed, cropland is the primary source of phosphorous, at 52 percent.

To date the state has relied on the carrot of financial assistance, often from federal agencies, to entice farmers to adopt best-management practices on their lands. Farmers have been encouraged to install stream buffers, plant cover crops in the winter months, and reduce tillage.

“I think there is consensus across the farm community that they need to make changes and improvements,” said Mears.

ANR and the Agency of Agriculture have been discussing how to both improve oversight of farms and provide more technical support for pollution reduction efforts, he said.

There’s been progress on reducing runoff from feedlots with compacted soils, but work still remains to be done on improving practices in crop fields, said Mears.

There is also the question of which, if any, best practices will be mandated.

The state will need to look at all farms, not just large-scale dairying operations, said Mears. “We need to do more outreach to those folks,” he said of smaller farms.

Mandated stormwater planning for communities is a possibility for reducing runoff from urban areas, according to Smeltzer.

That planning would likely include identifying current sources of phosphorous runoff and designing projects to reduce that runoff. The Friends of Northern Lake Champlain is working with several Franklin County communities on precisely that. But project will need to be implemented on a much larger scale to achieve the kinds of reductions required by the TMDL goals.

Road permits?

Stormwater permits for roads, both state and local, are another possibility under discussion.

All roads are contributing to stormwater runoff, said Mears.

Irene forced ANR and the Vermont Agency of Transportation (VTrans) to work closely and that relationship has continued, with the two agencies now cooperating to improve management of water coming from the state’s roads, according to Mears.

The practices being developed at VTrans, such as changes to ditching, will need to be implemented at the local level as well.

“People are looking very differently at road practices,” said Mears. “With VTrans’ help, there is a cultural change taking place.”

Within 20 years roads will be designed, built and maintained differently in Vermont, suggested Mears, who pointed out that designing roads to minimize erosion is smart investment.

“These are big lifts, obviously,” said Smeltzer of the needed changes to land use practices.

One of the more interesting analyses done as part of the TMDL development compared what would happen to Missisquoi Bay if phosphorous was reduced by 25, 50 and 75 percent tomorrow.

The only scenario under which the bay reached acceptable levels of phosphorous, defined as 25 micrograms per liter, was when phosphorous was reduced by 75 percent. Reductions of 25 and 50 percent did not reach the 25 microgram per liter level, not even after 30 years.

Missisquoi Bay and St. Albans Bay differ from the rest of the lake, in that they have large amounts of phosphorous stored within the their soil beds. Even if reduction targets were met, those two bays would take longer than the rest of the lake to show the effects, according to Smeltzer.

The Environmental Protection Agency (EPA) approved a TMDL baseline for Lake Champlain in 2002 that was calculated with data from the 1990s. EPA revoked that approval following a legal challenge to the TMDL findings by the Conservation Law Foundation.

EPA has been working with the state to develop new TMDL numbers using up to date data and more sophisticated models.

“I do think it’s the best shot that can be taken,” Smeltzer said of the new TMDL. “It’s still a combination of the best scientific information and some guesses in some cases.”

—  —  —

The first part of this report, published in the weekend edition, is available on the Messenger Web site (www.samessenger.com).