An unhealthy glow

The problem was an overabundance of phosphorus, which feeds algae, and now federal and state environmental authorities are trying to clean up the river’s infamous “dirty water’’ by drastically lowering its levels of the chemical.

A draft report from the US Environmental Protection Agency and the state Department of Environmental Protection calls for cutting annual phosphorous levels by 49 percent along the 70-mile upper and middle stretches of the Charles River. The state agency is accepting written public comments on the plan through Nov. 30.

Although some phosphorus occurs naturally, polluting levels are reached when storm-water runoff carries the substance from sources such as fertilizers, sediment, auto exhaust, and animal waste, and from waste-water treatment discharges. The problem is made worse by large developments and parking lots, according to the draft report.

The report urges waste-water plants to cut back the amount of phosphorus contained in treated water before it is discharged, a move that could lead operators to pass on the procedure’s higher costs to residents. It also targets businesses, which could see their costs rise if cities and towns adopt regulations to better manage storm water. Agencies responsible for major roadways would also have to clean up their act if the report’s limits go into effect.

“It is ambitious, but it’s necessary,’’ said Kate Bowditch, director of projects for the Charles River Watershed Association, which helped prepare the draft report in collaboration with the federal and state agencies.

She said the Charles has come a long way from when sewage drains oozed bacteria and viruses into the river, but there is still plenty of room for improvement.

The proposed limits in the report pertain to five communities - Waltham, Wellesley, Needham, Medway, and Millis - in particular, and to a lesser degree to 28 others, including Arlington, Lexington, Brookline, and Newton. (Similar limits were placed on the lower Charles, from Watertown to Boston, in 2007.)

State Representative Jennifer Callahan, a Democrat from Sutton, filed a bill after Bellingham, one of the communities she represents, was made part of a federal pilot program on reducing phosphorus levels. Her bill proposes tax credits or other financial assistance for towns or businesses that have to meet new storm-water regulations.

“My biggest concern continues to be if we’re going to put new policies and new regulations in place for both municipalities and businesses to have to address in the future . . . we have to think about ways to provide financial assistance,’’ said Callahan.

She said some businesses in her district spent hundreds of thousands of dollars to meet new phosphorous limits.

The Department of Environmental Protection said the draft report did not estimate costs because “they are highly variable and depend on individual site conditions,’’ spokesman Ed Coletta wrote in an e-mailed response.

The draft report does briefly address financial tools, mentioning some grants and the state’s Revolving Fund Program, which provides low-interest loans for pollution-abatement projects.

Algae are largely a problem for swimmers and boaters in terms of aesthetics and convenience, but also use up oxygen in the water, inhibiting aquatic life, according to the draft report. An outbreak of blue-green algae, or cyanobacteria, has never caused illness or death in Massachusetts, said Bowditch, although it does have the potential.

This is how the draft rules, if finalized, would work.

All municipalities would need to regularly renew their storm-water drain permits with the EPA. The drains are used by residents and businesses alike, making it likely that towns and cities would try to educate homeowners about proper fertilizer use and pet-waste disposal.

The state’s new Department of Transportation would be responsible for cutting down on phosphorus washing off its roadways, including the Massachusetts Turnpike, according to Bowditch. There are many new technologies that can be employed but one of the simpler actions is to use street sweepers more often, she said.

When it comes to regulating businesses, though, it could get complicated. The municipalities would have to figure out how to keep more phosphorus out of storm drains (and ultimately out of the river) with permits, ordinances, or zoning changes, said Bill Walsh-Rogalski, an EPA lawyer who worked on the draft.

For example, a town might create a regulation to require existing businesses to do more street sweeping, which can help capture phosphorus, or a city might require a new development to produce no new phosphorus, he said.

“The best thing to do is put the water back into the ground,’’ said Walsh-Rogalski, rather than into storm drains, since phosphorus gets filtered out of water as it moves through soil.

Another player in the draft report is waste-water treatment facilities, which would have to reduce phosphorus by roughly 65 percent.

Here again, questions on cost surface.

“We are deeply concerned about the health of the Charles River but feel going to extremes may or may not help the river, but it will cost the users millions of dollars,’’ said Cheri Cousens, an engineer and assistant chief operator for the Charles River Pollution Control District, which is based in Medway and also treats sewage for Franklin, Millis, and Bellingham.

Her plant has already brought down phosphorous levels significantly to meet federal standards, she said, and lowering it even more would require an additional treatment process, which translates into an upfront capital cost as well as new ongoing maintenance costs.

“Waste-water treatment plants are one source of phosphorus, and we think we’re being unfairly targeted,’’ she said.

Medfield is not quite as concerned. “Phosphorus is the easiest nutrient to remove,’’ said Ken Feeney, superintendent of the town’s Department of Public Works.

Peter Iafolla, chief operator of Medfield’s waste-water plant, said that may be so, but chemicals needed to cut down phosphorus are expensive, and one in particular, sodium aluminate, can be dangerous for workers to handle. “I really don’t like to use chemicals but it looks like the only way to do it,’’ he said.

Bowditch acknowledged the concern about cost but said there are models around the country and even in Massachusetts for addressing that.

For example, some municipalities, including Newton, have set up a storm-water agency that charges a fee to residents and businesses - like a water or sewer bill, Bowditch said, but much lower - that helps pay for whatever techniques are needed to keep phosphorus (or other contaminants) out of waterways.

“I don’t disagree with them that cost is a legitimate thing for all of us to look at,’’ she said.

Lisa Kocian can be reached at lkocian@globe.com.