SACO — What is at the bottom of the Saco River?

That is what researchers from the Maine Department of Agriculture, Conservation and Forestry’s Maine Coastal Mapping Initiative hope to determine this week.

Hydrographer Kerby Dobbs and a team from the Maine Coastal Mapping Initiative began work in the river Monday and expect to be finished today, said Dobbs. The crew is working out of the Amy Gale, a 35-foot lobster boat outfitted for survey work docked at Rumery’s Boat Yard in Biddeford.

Dobbs and the crew are using a device called a grab sampler to take samples of sediment. The grab sampler is fitted with a dive light and camera to record footage from the bottom of the river.

Scientist Ivy Ozmon said she is sifting through the sediment to determine what creatures are living there, and water samples are being taken for water quality testing.

The researchers are also using sonar mapping equipment and looking at the results on laptop computers to help determine the landscape of the river bottom.

The work is a precursor to a long-awaited dredging of a federal channel in the Saco River.

The Army Corps of Engineers has told local and state officials that submerged power cables, which got tangled in dredging equipment when the last dredging of the river occurred in the 1990s, and other debris must be removed before dredging can occur, according to a press release from the Maine Department of Agriculture, Conservation and Forestry.

The two cities are working together with hopes to get federal funding for the $3.2 million project in 2018, said Saco City Administrator Kevin Sutherland in a recent interview.

The proposed dredging would remove about 150,000 cubic yards of sand from the Saco River, creating an 8- foot-deep channel, and place it either in another location in the river or at the beach at Camp Ellis.

The channel has not been dredged since the early 1990s. Ideally, the channel should be dredged every 10 years, and the work is long overdue, according to Saco Public Works Director Patrick Fox.

Dobbs said he and the crew are trying to solve the “mystery of the alleged cable.” As of Wednesday morning, Dobbs said there was only anecdotal evidence of cables and no physical, tangible evidence.

However, he and the crew were going to further look at areas of the river that have come up on sonar maps as having signs of debris to determine if old cables or other refuse are in the water.

The Maine Coastal Mapping Initiative will document any anomalies found in the river, said Dobbs.

— Staff Writer Liz Gotthelf can be contacted at 282-1535, ext. 325 or [email protected].