A section of the Presumpscot River downstream from the Sappi mill in Westbrook was completely blocked by a landslide for several hours on Wednesday, but began to flow without forcing the evacuation of residents and businesses.
Mayor Michael Foley, who signed an emergency declaration shortly after 2 p.m., said later in the afternoon that water levels had fallen significantly and seemed likely to continue declining.
“The risk of imminent flooding is not really there,” Foley said Thursday.
The river, which gained notoriety when a giant ice disk formed in it in January 2019, was blocked after a landslide near an excavation contractor’s facility at 161 Warren Ave. that was reported at about 11:30 a.m.. The river rose from just under 2 feet to a peak level of 13.3 feet at 2:30 p.m. before dropping to 12.2 feet about three hours later., said Mike Ekster, a meteorologist at the National Weather Service office in Gray.
“It’s slowly receding and that’s what we want to see,” Ekster said.
Foley consulted with the Maine Emergency Management Agency before signing the declaration, which mobilized relief efforts and will help secure remediation funding from federal and state sources.
The flood watch advisory covering coastal Cumberland County that the weather service issued shortly after noon will continue into the evening as a precaution, Ekster said.
That area of Westbrook has a lengthy history of landslides because it has large deposits of marine or quick clay, Foley said — soft soil typically found in coastal areas that is notorious for causing landslides.
About 25 miles long, the Presumpscot is the largest freshwater input into Casco Bay, running from Sebago Lake through Windham, Gorham, Westbrook, Falmouth and Portland. It is a watershed of 648 square miles, according to presumpscotriver.org.
Differing accounts detailed the start of the landslide. Chris Wilson, owner of the excavating firm, said the slide began around 9 or 9:30 a.m. on an adjoining parcel owned by Sappi and the Portland Water District and consumed piles of aggregate he was keeping on his lot. He said his property extends toward the river from Warren Avenue, but stops before the river, the Portland Press Herald reported.
“After their land failed, my land and the neighbor’s land followed,” Wilson told the Press Herald. “A lot of money [his piles of aggregated material] went over the edge.”
Another witness, Jeremy Tardif, who was working on a job site finishing a concrete foundation that overlooks the area, said a bucket loader on the Wilson property was dumping earth on top of a large pile before the slide.
The city is investigating what started the landslide, but Foley said he doubted that any one cause will be found.
“There is really no instant solution,” he said. “I don’t think it is necessarily any one person’s fault. There is a long-term history of construction work and other things here.”