More than 130 volunteers will hit multiple sites on the South Portland and Portland waterfronts on Sunday in what the Friends of Casco Bay is calling a water sampling flash mob.

The volunteers will collect water samples simultaneously at 10:10 a.m., just before low tide, along the Fore River and Portland Harbor, from docks and piers and from kayaks and other boats, all in order to create a snapshot of the nitrogen levels in the ocean.

“Our nabbing nitrogen water sampling is a one-day, synoptic snapshot of the total nitrogen levels (on the ocean) in two of the largest cities in Maine,” Mary Cerullo, associate director of the Friends of Casco Bay, said in a press release.

“This first-of-its-kind, massive volunteer effort will help us map nitrogen levels in the Fore River and Portland Harbor—one of the most heavily populated regions in the state,” she said.

Cerullo added, “This (effort) may allow us to identify problem areas and explore sources of pollution (and) will (also) help our advocacy efforts with the state of Maine to establish a limit on how much nitrogen may be discharged into coastal waters.”

One they’ve collected their water samples, the volunteers will turn over the samples and data sheets to the Gulf of Maine Research Institute. If bad weather is predicted or approaching, the July 10 nabbing nitrogen event will be rescheduled to Sunday, July 24.

The nabbing nitrogen water sampling is important, Cerullo said, because “too much nitrogen can turn Casco Bay from a healthy blue to a slimy green.”

She said, “All living things need nitrogen to grow, but an overdose can trigger excessive nuisance algae, reduce water clarity and lower oxygen levels. This process also releases carbon dioxide, creating acidic conditions that can make it harder for clams and mussels to build and maintain their shells.”

Nitrogen pollution comes into Casco Bay from three different, land-based sources, almost in equal proportion, according to the Friends of Casco Bay – from sewage, from stormwater runoff and from air pollution.

Co-partnering with the Friends of Casco Bay on the nabbing nitrogen water sampling event are the Maine Department of Environmental Protection and the city of South Portland.

The project has also received funding from the Davis Conservation Foundation, the Birch Cove Fund at the Maine Community Foundation, the Horizon Foundation, the Maine Outdoor Heritage Fund, the Elmina B. Sewall Foundation, the Seth Sprague Educational and Charitable Foundation, RBC Blue Water Project, the Casco Bay Estuary Partnership and the Bowdoin College Common Good Grant, among other supporters.

– Kate Irish Collins