Rising sea level means Scarborough Marsh may have a wetter future
SCARBOROUGH — Steve Stracqualursi, an avid angler, said he sees changes when he casts his lines into Scarborough Marsh.
"I can catch more crabs than fish now. They grab right on to the line," Stracqualursi said during a Town Hall forum Wednesday on how rising sea level may affect the future of the 3,100-acre preserve.
Attended by perhaps 45 people, the workshop conducted by Assistant Town Planner Jay Chace, Peter Slovinsky, who is a marine geologist with the Maine Geological Survey, and Steve Walker of the Maine Coast Heritage Trust, took a look over the horizon to assess if and how the marsh can absorb elevated sea levels and endure the higher storm tides and surges that will accompany catastrophic weather events.
“This is not a 'Chicken Little' conversation,” Chace said at the outset. But data presented by Slovinsky suggested sea levels elevated up to 3 feet by the end of the century could place a substantial portion of the marsh under water and cause storm-related flooding on local roads and railroad tracks.
Based in part on readings over the last 100 years at the Portland tidal gauge and National Climate Assessment projections, Slovinsky said sea level rise estimates of 1 foot by 2050 and 3 feet by 2100 may actually be conservative, given the current rate of glacial melting.
Slovinsky estimated about 75 percent of the marsh is now "high marsh," generally above the water line. The remainder of "low marsh" areas are already experiencing an invasion of European green crabs because of warmer water temperatures.
Add elevated sea levels and the result may be a 50 percent reduction of high marsh areas and eventual inundation of current low marsh areas. A more drastic increase of 6 feet in water levels could put 60 percent of the marsh ecosystem under water, Slovinsky said.
Chace and town officials in Saco, Old Orchard Beach and Biddeford have been confronting the prospect of elevated sea levels on developed town areas for more than four years as part of the Sea Level Adaptation Working Group, known by its SLAWG acronym.
Marsh studies began this year in six communities selected by the ME Municipal Planning Assistance Program, using state provided data to examine potential local consequences.
Slovinsky also noted sea level rises will lead to increased storm tides and surges. U.S. Route 1 is now most affected by higher tides and flooding on the stretch through Scarborough Marsh near Milliken Road. A 2-foot increase in sea level could mean four miles of areas on Black Point, Pine Point and Snow Canning roads will face flooding problems with water depths as much as 4 feet if projections become reality.
The Pan Am railroad tracks used by the Amtrak Downeaster would also face flooding problems, as Slovinsky estimated adding 2 feet to the annual highest tide would put one mile of railroad tracks under water in a storm.
Nor'easters are as much a worry to Slovinsky as warm-weather storms. He noted some of the highest tides and surges recorded have come from cold-weather storms like the Patriots Day storm in 2007.
Slovinsky provided data Chace promised will soon be available on the town website, while Walker added visceral impressions from a visit to the Dunstan Landing area off Pine Point Road made just before the meeting.
Walker, who called the marsh “a big sponge out there,” said the Plymouth, Mass.- based Manomet Center For Conservation estimates marsh activities including fishing, birding and hiking create a value of $1,400 per acre annually in a local economy.
His visit to Dunstan Landing showed high marsh areas in retreat, compressing habitats for birds including least terns, several species of herons and the glossy ibis.
"As the sea rises, the marshes are going to gradually move inland,” Walker cautioned.
The workshop provided few directives for preserving the marsh. Slovinsky said the first steps are identifying the most vulnerable areas, while Walker urged people to begin monitoring conditions now.