Most lake pollution comes from lawns, gardens

Burlington Free Press
Sunday, March 24, 2002

By Nancy Bazilchuk
Free Press Staff Writer

Phosphorus from your garden and lawn fertilizer is the single largest pollutant in Burlington's stormwater, researchers say.

The finding comes from a $1 million, five-year University of Vermont study, now in its third year. UVM scientists are testing stormwater runoff to determine to what degree the water harms Burlington Bay.

Researchers thought they might find harmful levels of heavy metals, pesticides or petroleum residues in the stormwater. Although those substances were detected, the biggest surprise has been the high concentrations of phosphorus in the stormwater, said Angela Shambaugh, a research associate with the project.

Stormwater is the wash of rainwater that carries oil, grease and other pollutants from lawns and city streets into Lake Champlain. Burlington's stormwater carries enough phosphorus and bacteria into Burlington Bay to feed algae blooms that can sometimes make the lake unfit for swimming.

The research is timely. Twenty-five stream segments, half of them in Chittenden County, are so polluted with stormwater they don't meet state water quality standards.

In addition, the Environmental Conservation Department has failed to renew stormwater control permits for nearly a decade, allowing roughly 1,000 permits to expire. The majority of those permits are for projects that eventually drain into Lake Champlain. This lapse has contributed to the stream pollution problem.

Last summer, an appeal of a stormwater permit for a new South Burlington Lowe's Home Center showed developers the degree to which stormwater control -- and the existing pollution problems in the streams -- have become an integral part of development approval process.

In response to the Lowe's situation, the House passed a bill now being considered by the Vermont Senate that the bill's sponsors say would unsnarl the state's permitting woes while protecting streams. Bill Bartlett, executive officer of the state's Water Resources Board, says the bill would be the worst setback for water quality in 25 years.

"Given all the arguments in the state about stormwater right now, we need to do all we can to locate these sources and keep them out," said Alan McIntosh, director of UVM's Water Resources and Lake Studies Center, and a principal investigator in the Burlington Bay project. "I'm hoping as we move ahead, we'll educate people about what they can do to help, whether it's about fertilizing their lawns or using a pooper scooper."

Blue-green algae

Too much phosphorus in the lake feeds the growth of nuisance weeds and algae.

The phosphorus in Burlington's stormwater comes from anywhere fertilizer is used: lawns, gardens, golf courses, fields.

Thirty years ago, the biggest source of phosphorus for the lake was raw sewage. Sewage treatment plants have eliminated raw sewage and cut down on the phosphorus problem. Now, the major sources of phosphorus are farms and urban areas. Farms contribute 55 percent, and urban stormwater is responsible for 38 percent , according to a 1999 analysis for the Lake Champlain Basin Program. Yet urban areas cover just 5 percent of the land that surrounds Lake Champlain.

Shambaugh said some of the stormwater samples showed phosphorus levels several hundred times higher than the amount of phosphorus allowed in the lake itself.

Shambaugh is looking at what adding all that phosphorus to the bay does to algae growth, particularly blue-green algae, which in the right conditions, can produce a toxin in lakewater.

In the summer of 1999, three dogs were poisoned by blue-green algae after they drank large amounts of water from the lake. Blue-green algae is common in the lake, but the dog deaths were the first time the algae produced enough toxin to affect animals.

McIntosh said the work will help the Health Department as it monitors swimming conditions in the lake. In the summer of 2000, for example, Shambaugh found that blue-green algae in the lake was again producing toxins. Researchers are still analyzing results from last summer.

"Phosphorus is basically plant fertilizer, and aquatic plants are no different than the plants in your garden," Shambaugh said. "The more phosphorus we put into the water, the more is available for plant (and algae) growth. It's essentially like adding fertilizer to your lawn."

Bacteria and oil

The Burlington Bay research also shows that bacteria routinely contaminates Burlington's stormwater at levels far higher than those established by the state to protect human health.

Domestic dogs and cats and wild animals such as foxes and raccoons are the culprits.

The high bacteria levels are the reason for the permanent closure of Blanchard Beach, near Oakledge Park, and can contribute to occasional beach closings at other parks, says Steve Roy, a project engineer with the City of Burlington. Roy is coordinating a $1.3 million cleanup of Englesby Brook that's also being funded by Green Mountain Power as part of the Barge Canal Superfund settlement.

Oil and gasoline also routinely contaminate stormwater, so much so that petroleum products are accumulating in sediments near a drain from College Street.

Roy says the results of the stormwater research confirm that nearly every city resident has a share of the responsibility.

"It is caused by each and every one of us," Roy said. "It's caused by our habits and what we do and don't do, whether it's our fertilization practices to keep the lawn looking green or walking the dog and not picking up after it."

Water fleas

McIntosh and Shambaugh want to know if the mix of contaminants in stormwater could harm aquatic creatures. But making that direct link in the bay itself is impossible. Any number of factors -- aside from polluting stormwater -- can harm or kill small fish, animals and insects in the water.

Shambaugh and her co-researchers are raising water fleas in her lab at UVM's Rubenstein Ecosystem Science Laboratory at the bottom of College Street. Water fleas come in two sizes. One species is no bigger than the head of a pin and the second the size of a poppy seed.

The big fleas are the canaries in the coal mine. Researchers expose the fleas to samples of stormwater to see if it kills them.

Researchers use the smaller variety fleas as miniature guinea pigs. The fleas are bred in pampered conditions and then they're exposed in the lab to stormwater directly from Burlington storm drains. Some of the fleas aren't exposed to the tainted water. That gives scientists the ability to compare the reproduction of fleas in clean water to that of the fleas in stormwater-laced water.

Water fleas stop reproducing when they're stressed by contaminants. "They don't tend to show malformations as much as they just don't have babies," Shambaugh said.

Some of the water flea research has been surprising.

Stormwater collected near Leddy Beach, which drains a mostly residential area, significantly lowered water flea reproduction several times in the summer of 2000, Shambaugh said, a sign that something in the stormwater was harming them.

Yet when researchers analyzed the stormwater samples to see what kinds of toxic chemicals they contained, they found no obvious culprits.

Shambaugh says even before researchers pinpoint the exact effects of stormwater, residents can still take some common sense steps to reduce the problems it poses.

Reducing the amount of fertilizer on lawns, picking up pet waste and not emptying wastes down storm drains helps protect the lake, she said.

"We can't act like it's going to go away when it goes down the drain," she said, "because it doesn't."

Contact Nancy Bazilchuk at 660-1873 or nbazilch@bfp.burlingtonfreepress.com