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Estuaries in New Hampshire are still ‘fairly sick,’ but showing signs of improvement

Blue herons in the Great Bay at low tide
Amy Quinton / NHPR file photo
Blue herons in the Great Bay at low tide

New Hampshire’s estuaries are showing some signs of improvement, according to a new report from the Piscataqua Region Estuaries Partnership (PREP) at the University of New Hampshire. But the group of advocates, officials, and scientists behind the report say they’re still facing challenges.

Stressors like climate change and increasing human development threaten the ecosystems of estuaries, said Piscataqua Region Estuaries Partnership director Kalle Matso. And he says their vital signs are not good.

“Because it looks beautiful as you drive in your car and when you do certain hikes, people don't realize that our watershed is actually fairly sick. If it was a patient in a doctor's office, you would be highly concerned,” he said.

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PREP’s “State of our Estuaries” report says positive indicators – those that demonstrate improvement in the estuaries – include shellfish harvesting opportunities, bacteria, nutrient concentrations, conserved land, and seaweeds.

Excess nitrogen coming from sources like wastewater treatment facilities is the lowest it’s been since reporting started in 2003, and more communities are adopting standards for stormwater management that help protect the estuaries.

Other signs of improvement include an overall increase in oysters, which are at their highest level since 1998.

“The region’s oyster aquaculture industry has never been more vibrant,” the report says.

The levels of natural oyster reefs are still down 80% from where they were 30 years ago.

Eelgrass, which can help keep estuaries resilient against challenges, is continuing to increase in the Portsmouth Harbor region. And migratory fish are returning to the watershed in the highest numbers since 1992, following the removal of a dam in Exeter.

But some trends indicated deteriorating conditions in the estuaries, the report said.

Trends for salt marshes, beach advisories, and softshell clams were the most concerning, according to the report. Salt marshes are being impacted by sea level rise, and beach advisories have shown a sharp increase since 2017. Softshell clam populations have continued to decline since 1997.

Excess nitrogen that can’t be pinned to a particular source has increased by 15%, and new contaminants were found in blue mussel tissue.

The report also measured community involvement. Volunteer hours decreased during the pandemic, but the authors said federal and local leaders have begun to work together more effectively, particularly on permitting decisions.

Matso said residents who live near the estuaries, and their community leaders, can play a big role in protecting the bodies of water.

“It’s not impossible to grow," he said, “and to protect the environment at the same time,” he said.

It might take more work, he said, but considering how developments like new buildings, stormwater infrastructure, and choices about land conservation affect watersheds can make a big difference.

Mara Hoplamazian reports on climate change, energy, and the environment for NHPR.
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