GREENFIELD — The water level in a large beaver pond off Spier Falls Road has dropped as much as 6 feet since a culvert was opened under a railroad track bed late last week, the town supervisor said Monday.

But a considerable amount of water remains in the pond, said Supervisor Richard Rowland.

A stream called Mud Creek runs in this area off Spier Falls Road and Route 9N in Greenfield. The creek usually runs through a large culvert under former Canadian Pacific Railway Company tracks that go from Saratoga Springs to Corinth.

In recent weeks the beavers plugged the culvert solid and what had been Mud Creek “turned into Mud Pond,” Rowland said.

Highway department and fire company personnel from Greenfield and Corinth were able to create an opening in the culvert last week and water has slowly been draining from the pond. Rowland said Mud Creek drains into a tributary of the larger Kayaderosseras Creek.

Rowland said he is keeping the limited state of emergency he declared Oct. 5 in place because rain is in the weather forecast through the end of the week.

Rowland said the culvert has been opened but is still substantially plugged by the beaver dam.

“Once the water level drops more, we are going to go in and get the bulk [of debris] out of the culvert,” Rowland said.

The supervisor added that he noticed over the weekend increased “evidence of beaver activity.” He said some trees were downed with beaver chew markings on them.

He said town and state officials are looking at a variety of alternatives to remove the beavers from the Mud Creek area, including trapping the animals.

“The beavers will start to plug it up again,” Rowland said.

Town and county officials are afraid that water building up behind the railroad bed could undermine the railroad bed and send a wall of water rushing down toward roadways and homes. A beaver dam created behind railroad tracks off Daniels Road did just this in May 2006. The rush of water damaged roadways, private property, and required an expensive rebuilding of the railroad bed in this area.

The town of Corinth purchased the railroad tracks between Saratoga Springs and Corinth several years ago using a federal grant. The town and county want to start running tourism and ski trains on the tracks once they are brought up to proper grade.

Rowland said that Taylor Pond and another small pond both feed into Mud Creek. When the beavers blocked the flow of water through the railroad bed culvert, a pond of between 100 acres and 200 acres was created behind the tracks.

Rowland said the town was helped by the cooperation of two dozen different agencies.

“This was intermunicipal cooperation at its finest,” Rowland said.

In addition to the highway departments and fire companies in Corinth and Greenfield, several state agencies, the Saratoga County Office of Emergency Management, state police and the county sheriff’s office all helped during the emergency.