River remedies

With phosphorus choking water in the Assabet, a project to upgrade treatment plants offers hope

Email|Print| Text size + By John Dyer
Globe Correspondent / December 2, 2007

Everywhere, phosphorus abounds. It's in the soil, plants, even our bones. It's in fertilizers, matches, and toothpaste. The problem is, loads of the natural element also are in the Assabet River, where it is gagging the water and polluting sediment from Westborough to Concord.

Specialists say it's time for a cleanup.

"If you have too much phosphorus, you have too much algae and aquatic plant growth," said Susan Beede, acting executive director of the nonprofit, Concord-based Organization for the Assabet River, or OAR. "It's not pleasant to swim in the river and, where it's weedy, it's dangerous."

Much of the phosphorus in the Assabet comes from humans, in waste water treated by antiquated municipal sewage plants and dumped into the river. Tomorrow, state officials are expected to approve more than $80 million in upgrades to four such waste-water-treatment facilities along the 32-mile-long Assabet - improvements designed to eliminate the phosphorus discharge. During the summer, effluent from treatment plants can be a whopping 80 percent of the Assabet's flow.

The proposed changes, mandated by state authorities in 2004, will be good for the environment of Boston's western and northwestern suburbs, river advocates say. But they will not bring an end to the issue, which is also faced by communities elsewhere in the Commonwealth that have older waste-water-treatment plants along waterways.

Along the Assabet, local sewer and water customers must pay for the upgrades, and changes to treatment plant technology will not remove phosphorus currently saturating the riverbed. To do that, dams along the Assabet may have to be removed, a possibility some local officials find disconcerting.

Renovation costs for the plants in Hudson, Marlborough, Maynard, and Westborough range from $16 million to $30 million, said Rick Dunn, a watershed specialist at the state Department of Environmental Protection. That money also will pay for routine improvements to the aging plants. But each city and town has a schedule as to when new filters should be installed to properly remove phosphorus, with all now expected to be online by mid-2011 or earlier.

The changes will be pricey for residents who pay local sewer and water bills. Northborough homeowners who use the town's sewer system, around a third of the residents, could see the largest increase. Their bills might double to $900 a year, according to preliminary projections, said Public Works director Kara Buzanoski. Northborough sewers are connected to Marlborough's Westerly Treatment Plant.

At the other end of the spectrum of rate increases is Concord, where upgrades were completed recently. Concord ratepayers' bills could increase by $40 to an annual average of $800, said Alan Cathcart, superintendent of the town DPW's water and sewer division. Cathcart said the town had been preparing for the $15 million in upgrades with steady increases over the past few years.

"It's not going to be a rate-shock situation," he said.

Hudson Executive Assistant Paul Blazar said the high cost of the upgrades reflects a lack of state or federal aid. Ratepayers are footing the entire bill, he said. But, at the same time, he said, ratepayers also live near the river and benefit most from its improvement.

"People care about the environment, but everything is a balancing act," Blazar said. "How do you equate how much people care with an amount of money?"

Phosphorus, a natural element, normally leaches into rivers from decaying leaves and other organic materials, Beede said. The Assabet is now overloaded with phosphorus because the four waste-water-treatment plants being upgraded are outdated and cannot properly do the job. The plants remove and convert solid-waste materials into sludge, but allow the phosphorus to pass into the river.

"Phosphorus is necessary for life. It's not some pesticide that we created after World War II or anything," Beede said. "It's a natural element so plants will grow."

As a result, the Assabet contains an enormous amount of fertilizer that fosters algae blooms and duckweed, especially in the summer, when the plants decompose and produce the river's trademark rotten-egg smell. The algae and weeds, Beede said, also consume and expel too much oxygen, hurting some fish species.

State and local governments across the country have passed laws to curb the use of phosphorus in consumer products. In Massachusetts, phosphorus has been banned in laundry soap for years. The state Senate recently passed a bill sponsored by Senator Pamela Resor, Democrat of Acton, that would ban it from dish detergents. The House of Representatives is considering the bill.

The treatment plant upgrades will remove enough phosphorus in the waste water to eliminate half of the weeds and algae blooms, Dunn said.

But only 60 percent of the Assabet's phosphorus comes from the daily discharges of the treatment plants, said Tom Parece, a Concord-based consultant with Earth Tech, a firm working with the towns on the upgrades. The rest is what has accumulated in the muck at the bottom of the river, especially in the pools that form at the bases of the Assabet's dams.

The Army Corps of Engineers is conducting a $1 million study of the merits of removing six dams on the Assabet to help the river's current clear out phosphorus.

"It's apparent the dams slow down the flow of water and contribute to the water-quality issues," said Barbara Blumeris, who is managing the study, due to be published in March.

Already, however, local folks are worried about their dams disappearing. In Maynard, Selectwoman Sally Bubier said that the 1850s-era Ben Smith Dam near Clock Tower Place allowed industry to blossom in the town and that losing it would be a blow to Maynard's identity.

"Maynard is here because of the mill, and the mill is here because of the dam on the river," she said.

Bubier also wondered whether removing a dam that had been in place for so long would harm rather than help the local environment. "You have a 170-year-old ecosystem you are now going to mess with."

Patricia Perry, administrator of Stow's Conservation Commission, said her town would be hard hit if dams were removed on the Assabet because the town depends on them for keeping the river at its current water level.

"The river will change. It won't be as wide as it is deep," she said. "The wetlands will change. Wildlife habitat will change. Stow relies heavily on the river for fire protection. A lot of the farms irrigate from the river."

The Organization for the Assabet River has not taken an official position on whether the dams should go, but Beede said dams have turned the Assabet into more of a long pond than a moving channel, fostering still-water fish that can deal with the extra vegetation, like large-mouthed bass, carp, and perch, but excluding normal river fish, like trout, that thrive in clean, swift currents.

"Right now, there is a lot of questions hanging over these dams," Beede said. "Certainly there are benefits to dam removal but it's not a black-and-white issue."

Whether the dams go or not, Beede said she is optimistic that the upgrades of the waste-water-treatment plants, though costly, would help restore the Assabet to at least a shade of its former glory.

"The exciting thing is that the river is going to improve," she said. "The river really is beginning to enjoy a renaissance. We have treasure in our backyard."

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