At the mouth of the Charles River, where it meets Boston Harbor, the water seems clear, the river picturesque, the surface reflecting the city’s modest skyline. But further down, the Charles’s 70-mile main stem is an over-fertilized breeding ground for algae.
On September 30, a 10-year study by the Charles River Watershed Association—a nonprofit environmental organization—confirmed the river’s overabundance of nutrients. High levels of phosphorous—an important nutrient—has over-fertilized the aquatic ecosystem, causing runaway planktonic growth that renders the waterway toxic to its larger organisms and unappealing to fishers. The Massachusetts Department of Environmental Protection and the US Environmental Protection Agency released a draft report on September 30 that calls for cutting the annual phosphorous levels of the river’s upper and middle portions by 49 percent.
If the draft report is finalized, municipalities in the Charles’s vicinity would have to take measures to reduce phosphorous contributions from stormwater runoff and wastewater treatment facilities. The proposed limits pertain to the towns located in the river’s watershed—Medway, Millis, Needham, Waltham, and Wellesley—and portions of 28 more, including Arlington, Lexington, Brookline, and Newton. The state agency is accepting written comments on the plan through November 30.
Reaching the Limit
Nutrients are vital to all organisms and ecosystems. A nutrient is a chemical that an organism needs to live and grow, a substance that enriches the body, like carbohydrates, fats, proteins, vitamins, and inorganic chemical compounds like water and oxygen. In freshwater ecosystems like the Charles, phosphorous is what environmental scientists refer to as the limiting nutrient. It is the ecosystem’s scarcest nutrient and limits primary organism reproduction. Normally, the primary organisms cannot reproduce beyond what is allowed given the quantity of phosphorous. When there are large levels of the limiting nutrient, the primary organism—algae, in the case of aquatic ecosystems—growth explodes.
The river’s current phosphorous level has environmental, aesthetic, and recreational ramifications. The waterway is “choked by weeds and huge blooms of algae,” according to Kate Bowditch, the Charles River Watershed Association’s Director of Programs. The speed of vegetation growth stresses the river’s fish populations. The Charles also contains a toxic cyanobacteria masquerading as an ordinary blue-green algal bloom. Three years ago, one such toxic bloom led to the postponement of a swimming race.
A Total Maximum Daily Load Analysis (TMDL)—a calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards—of nutrients in the Charles River’s upper and middle sections began in 2000. The Federal Clean Water Act of 1972 requires that states undertake a TMDL when a body of water is severely impaired. The river’s nutrient levels currently exceed federal water quality standards.
Straight to the Source
Phosphorous is abundant in the natural environment, but polluting levels are reached from “combined sewer overflows (CSOs), wastewater discharges, stormwater runoff, accumulated organic sediments on the river bottom, and some groundwater sources,” according to the report.
Among these sources, wastewater, stormwater, and benthic sediments are the primary human sources of phosphorous in the Charles. Stormwater is the leading source of the Charles’s phosphorous, both during the summer and winter. In the summer months, stormwater contributes to 78 percent of the river’s phosphorous; wastewater and benthic sediment—the underwater accumulation of organic sediments that release nutrients—contribute 16 percent and seven percent, respectively. During winter, stormwater is still the leading source of phosphorous at 70 percent; wastewater is 22 percent, and benthic sediment is seven percent.
Stormwater runoff from rooftops, driveways, roadways, and vegetated areas “carries phosphorous that is adsorbed”—accumulated on the water’s surface—“to sediment and dissolved in the water,” according to the report.
Many human activities are known to raise the level of phosphorous in stormwater, particularly the use of lawn fertilizers, car wash products, and certain detergents. Car exhaust, other oil byproducts, pet waste, and lawn clippings are additional sources of phosphorous.
All municipalities would be required to regularly renew their stormwater drain permits with the EPA. The Massachusetts Department of Transportation would be responsible for reducing the phosphorous that washes off of roadways and contributes to the nutrient’s presence in stormwater runoff. Bowditch suggested more frequent street sweeping as one possible measure to cut the phosphorous in roadways.
A waste…of money
The draft calls on wastewater treatment facilities to reduce phosphorous by approximately 65 percent. A reduction this high will be costly, and operators at several facilities expressed financial concerns.
“It’s just a major reduction. We’re going to have to take low-interest loans out to pay for it,” Cheri Cousens, an engineer and assistant chief operator for the Charles River Pollution Control District, said. “I’m just not sure if that reduction is necessary.” Cousens noted that her plant has already reduced its phosphorous levels in accordance with federal standards.
But Ken Feeney, the superintendent of Medfield’s Department of Public Works, is less concerned. “Phosphorous is the easiest nutrient to remove,” Feeney told the Boston Globe.
Others are concerned about the actual process of eliminating phosphorous. While Peter Iafolla, the chief operator of Medfield’s wastewater plant, agrees that phosphorous is the easiest nutrient to remove, he noted that the required chemicals are expensive and dangerous.
But Bowdich does not think that money should even be a point of contention.
“Every time we’ve taken significant changes to clean up our rivers and streams, people have been very anxious about the cost, and people have been very unsure about whether the results were going to succeed and whether it was going to have a beneficial impact. Especially in the case of clean water, it has succeeded,” Bowditch said.
She noted that representatives from treatment facilities suggested that tackling the stormwater problem should be the top priority. “They feel like stormwater is the biggest problem, so why don’t we just go back and talk to them when we’ve cleaned the stormwater? We did a simulation that showed even if we did everything that we thought could be done to clean up the storm water, it still wouldn’t be enough to reach the target levels of phosphorous,” Bowditch said. “The only way to reach the targets was to reduce the phosphorous in the wastewater plants.”
Fish and humans both have a stake in the water quality of the Charles River. The algal blooms’ stress puts a stress on the entire ecosystem. Bowditch noted that there is a tremendous amount of sedimentation at the bottom of the river, because “year after year, the plant material dies and settles. We’ve lost a lot of the good bottom environment for fish.”
“There are obvious ecosystem impacts as well as human recreation and public health impacts,” she said. “It’s very clear that if we don’t take these measures to reduce the phosphorous now, we’re never going to make any progress on the problem.”
It’s not clean unless KATIE LINDSTEDT B’11 can take a bath in it.