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May 21, 2024 2:52 pm

Local News

Stormwater Runoff Problem: Efforts Continue To Clean Up New Hampshire’s Great Bay

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by Hadley Barndollar, New Hampshire Bulletin

The Conservation Law Foundation filed a petition this week urging the Environmental Protection Agency to regulate stormwater pollution coming from commercial and industrial properties surrounding the state’s Great Bay.

Filed under the Clean Water Act, the petition points to stormwater runoff as a “significant source” of harmful nitrogen pollution in the estuary spanning more than 6,000 acres in Rockingham and Strafford counties. 

Designated as one of 28 estuaries of national significance under the EPA’s National Estuary Program, Great Bay has experienced water quality issues for years as a result of nitrogen pollution – as high as three times the levels acceptable for eelgrass health, for example.  A map provided by the Conservation Law Foundation outlines the expanse of Great Bay through communities across Rockingham and Strafford counties. (Source: Conservation Law Foundation)

Eelgrass is considered one of the ocean’s most important plants, performing functions such as protecting the coastline, mitigating climate change, and improving water quality. Great Bay’s eelgrass “has declined so severely that in some places in the estuary only half the population remains, and in other estuarine locations eelgrass has disappeared entirely,” according to CLF. 

“The rivers and streams flowing into Great Bay are being inundated with polluted stormwater every time it rains,” said Melissa Paly, CLF’s Great Bay Piscataqua waterkeeper, in a statement this week. “The nitrogen in this stormwater runoff is harming the waterways that make New Hampshire’s Seacoast such a special place to live and visit, and it cannot be allowed to continue. Many of our communities have made great strides in reducing pollution from wastewater, now it’s time to step up and reduce pollution in stormwater.”

CLF’s petition focuses on large commercial, industrial, and institutional properties located on the Great Bay watershed. Stormwater runoff from large parking lots, big box stores, and strip malls, for example, aren’t regulated by the EPA. But CLF wants them to be, because properties as such contribute significant runoff to neighboring wetlands, streams, and rivers. 

According to the state Department of Environmental Services, nitrogen often reaches the estuary through stormwater via atmosphere deposition, chemical fertilizers, human waste through septic systems, and animal waste.

Great Bay has been the subject of costly, at times controversial cleanup efforts in recent years. The EPA previously issued a total nitrogen general permit to the 12 communities that discharge wastewater into the estuary and bodies of water that feed it. The goal of the permit, which runs through 2025 and is renewable thereafter, is to regulate how much nitrogen is entering waterways. Early predictions from municipal leaders pegged the total cost to meet the permit requirements at around $1 billion over 20 years.

And yet, despite investments made by cities and towns to upgrade their wastewater treatment plants or build new ones entirely, “science shows that the Great Bay estuary will not be restored to a healthy condition until stormwater pollution is addressed,” CLF says. 

This story was written by Hadley Barndollar, a reporter at the New Hampshire Bulletin, where this story first appeared.

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