Rain Gardens Promise Way to Limit Runoff Polluting the Bay

Randy Schmidt, background, with one of the sisters of St. Joseph planting a rain garden in 2017.

To solve your stormwater runoff and pollution problems, put the land and its flora and fauna — or at least strategically located patches of it — back to the way it was before we paved and planted it with lawns.

That was the unspoken subtext of everything landscape ecologist and wildlife biologist Rusty Schmidt told the 25 people gathered for what was billed a “Rain Garden Summit” in the Sag Harbor Municipal Building on Monday. The event was organized by Mary Ann Eddy, chair of the village’s Harbor Committee, which is charged with protecting Sag Harbor’s bays and wetlands.

Randy Schmidt at Monday’s “Rain Garden Summit.” Peter Boody photo

A rain garden, Mr. Schmidt explained, is a “shallow bowl” in the terrain planted with mostly native vegetation that collects rainwater runoff. The vertical pathways created by the long roots of the native species dramatically boost the absorption of water deep into the soil. Not only does that reduce the volume of water rushing through catch basins directly into surface waters, it filters out most of the runoff’s load of nutrients, toxins and pathogens — a must if the Peconic Bay system is to return to good health.

“It’s all about the roots,” Mr. Schmidt emphasized with a slide of an exhibit at the National Botanical Arboretum in Washington, D.C. showing the surprisingly long roots of native prairie grasses. The roots of typical lawn grass, he noted, barely penetrate the top inch or two of the soil.

With more than a dozen designs for rain gardens approved and funded and on track for  installation across Sag Harbor’s waterfront from Terry Drive in the Azurest community on the east to Middle Line Highway’s terminus at Round Pond on the west, Sag Harbor soon should begin to follow the example of towns like Maplewood in his native Minnesota, where “you’ll drive by a thousand rain gardens” along highway rights-of-way “and not realize it,” Mr. Schmidt said, because they all look like colorful border gardens in front yards.

Mr. Schmidt, who designed most of the rain gardens slated for Sag Harbor as a scientist with the village’s environmental consulting firm, Nelson, Pope & Voorhis of Melville, announced the news that “as of today” (March 9) still another government funding source had come through for the local rain garden initiative. Thanks to revenues now pledged from Suffolk County’s quarter-percent sales tax for water quality projects, the village will be installing rain gardens on Bay Street south of Havens Beach.

Funding also has been secured from the Community Preservation Funds of the towns of East Hampton and Southampton as well as the county-administered Peconic Estuary Program (PEP). Mr. Schmidt said seven rain garden projects are being funded by the Town of Southampton; four by the Town of East Hampton, and two by the PEP.

Describing a rain-garden project he designed and implemented for a suburban neighborhood in the city of Burnsville, Minnesota beginning in 2002 — before he moved to Long Island seven years ago — Mr. Schmidt reported that by 2004 he had documented an 83-percent reduction in the volume of water reaching catch basins that direct it into nearby Crystal Lake. By 2005, the neighborhood’s street-side gardens had captured 90 percent and, the following year, 93 percent as their roots developed.

Nor only do rain gardens dramatically reduce the threat of polluted runoff reaching open water, he said, they are aesthetically pleasing and added 5 percent to the value of residential properties, according to data he has collected. Once established, they only require weeding twice a year, in April and early July, he said.

If a homeowner does not keep up the rain garden adjacent to his or her property, the city of Burnsville will remove it instead of letting it turn into a weed patch. “One bad rain garden creates 10 times more talk than the 50 good ones beside it,” Mr. Schmidt said.

Data he collected on the expansive rain garden program in Maplewood, Minnesota, launched in 1997, showed that only one out of 20 homeowners failed to keep up the rain gardens adjacent to their yards. By seven years ago, when he left the area, the community had created 750 rain gardens and now probably there are more than 1,000, he said.

Mr. Schmidt also featured a large rain garden he installed in 2017 to solve the problem of a huge puddle that lingered in the parking lot after heavy rains at the Sisters of St. Joseph convent in Brentwood. A large clump of privet was removed, the soil was loosened, black compost was added, 1,500 native plants were put in the ground — most of them by Mr. Schmidt and one of the sisters — and mulch was spread on top. Two weeks later, there was a heavy rain and no puddle in the parking lot, he said.

During a question-and-answer period, Mr. Schmidt said homeowners can install their own rain gardens at a cost of about $12 to $14 per square foot if they use a landscape contractor. If they do the preparation and planting themselves, the cost could drop to $4 or $5 a square foot.

Rain gardens do not attract mosquitos, he said; in fact, they act as mosquito traps, luring the insects to lay their eggs in standing water after a heavy rain but then stranding them as the water rapidly seeps into the soil long before the eggs can hatch.

As questions turned to runoff problems at Havens Beach, Mr. Schmidt urged the village to consider diverting the drainage ditch or dreen there into a “serpentine” channel to slow the runoff it carries from the Hempstead Street catch basin, allowing more of it to percolate underground before reaching the bay.

“I have very little say in a municipality’s ideas or actions, but as citizens you should be able to make your voices heard,” Mr. Schmidt said in response to a call for rain gardens to be installed at the entryway to the village on the Sag Harbor Turnpike. Dai Dayton, president of the Friends of the Long Pond Greenbelt, made the suggestion because of the county’s plan to upgrade of the turnpike, which she said will exacerbate a runoff problem. Ligonee Brook, which runs along the base of the turnpike’s downhill slope, connects directly to Round Pond in the Long Pond Greenbelt.