Taking stock of the busy work of beavers

Wildlife and natural resource experts tend to talk about beavers, the state’s largest rodent and off

Wildlife and natural resource experts tend to talk about beavers, the state’s largest rodent and official animal, with admiration of their substantial dam-building abilities.

With man-made dams in the spotlight over the past few years — particularly the pending overhaul the Schoharie Reservoir’s Gilboa Dam and state plans to beef up dam inspection regulations — Schoharie County officials are beginning an inventory of beavers’ handiwork.

Despite widely acknowledged benefits of beaver ponds in creating habitat for other wildlife, birds, fish and amphibians, scenic and recreational areas, and even flood control, failure of the mud and stick dams can pose dangers downstream.

Sometimes, even the beavers’ legendary engineering skills are not a match for major storms, which climate forecasters say seem to be coming more frequently in recent years.

“My concern is what happens down below [the damworks],” said Judith Warner, director of the Schoharie County Emergency Management Office.

“With any dam that’s regulated you have an emergency action plan, and a way to notify people,” Warner noted. “But beavers don’t get a permit … and with beaver dams, we don’t really have a handle on where the dams are.”

That’s exactly what the inventory is designed to accomplish, according to Zachary Thompson, coordinator of the project for the county’s Planning and Development Agency.

technology employed

Once the dams are located, mapped and measured by Thompson and satellite mapping technician Brian Fleury, computer modeling studies will be used to project what might happen to roads, homes or property downstream if a beaver dam broke.

The project, using satellite mapping and information systems, and laser-guided measuring instruments, is still in the planning stages.

With access to private property complicating the study, Thompson is seeking the help of landowners to tell the county Planning and Development Agency’s Cobleskill office about dams on their property.

Thompson can be reached at (518) 234-3751.

A June 23 incident in the town of Jefferson highlighted a need to map the dams, Thompson said. A beaver dam west of state Route 10, near Moxley Street, partially broke, sending a couple of feet of water to a nearby farm, threatening some baby goats, he said.

As it turned out, by the time state highway workers went to check the dam the next day, “they saw the beavers were already working on it,” said Peter Nichols, stream project manager with the county Soil and Water Conservation District.

Nichols is providing technical assistance for the inventory.

Like most local beaver dams, the Jefferson pond is out of sight, and on private land or near houses or cabins used only seasonally for vacations or hunting camps.

“The Jefferson situation is a little tricky because there are two dams that span four properties,” according to Thompson.

Even though the beavers typically rush to quickly fix any dam breach, usually at night, “every beaver dam is a risk to some degree,” Nichols said.

“The beaver dams provide habitat for wildlife, but it’s where you draw the line between the benefits and the risk,” Nichols said.

beavers admired

With inborn skills, beaver colonies have built large dams that have held solidly for decades, Nichols noted with admiration.

One dam along upper Mill Valley Road, in the town of Middleburgh, near the Cobleskill and Fulton town lines is more than 6 feet high and about 120 feet long.

“It’s been there years and years,” Nichols said. A pond of at least an acre is estimated to hold as much as 2 million gallons of water above a narrow gully that carries the headwaters of tiny Line Creek under Tinkley Holly Road, through a 36-inch diameter culvert.

If the dam, sitting at about 1,800 feet above sea level, were to break, portions of the seasonal roads would likely be washed out.

A couple of seasonal homes might be affected, officials project. But the water would likely spread out and lose much of its force by the time it reached more populated areas and farms a few miles downstream near state Route 30, Warner believes.

Mapping and computer modeling of effects would help officials better plan, or lessen threats, according to Nichols.

Complicating the process is that property owners have obvious authority over the land.

But the state does maintain some jurisdiction over the damworks, according to state Department of Environmental Conservation rules.

“No person is allowed at any time to disturb a beaver’s dam, house or den without written permission from the DEC,” according to state Environmental Conservation Law.

That includes highway crews, governmental officials and farmers, said Josh Choquette, a wildlife technician who deals with beaver issues out of DEC’s regional office in Stamford.

“The biggest concern that we have been facing is we have a lot of landowners that contact us and say they have a neighbor above [them] with a beaver dam,” he said.

Legal issues

If a dam fails, however, the liability is not with the state, according to a 1917 state Court of Appeals decision in Barret v. State of New York.

That ruling reversed a state compensation award stemming from property damage by a beaver, according to a comprehensive beaver-control manual available online through the nuisance animals link on the DEC’s Web site.

Permits are regularly issued, however, to trap, shoot, or otherwise control problem beavers, noted Choquette.

Any alteration or breaching of a beaver dam requires a DEC permit, with the goal to allow water to be released slowly to avoid potential damage or flooding downstream, he said.

Choquette is scheduled to discuss beaver dams and control options at the county Board of Supervisor’s Aug. 28 flood committee meeting.

Almost never are problem beavers relocated alive. “It would have to be a very extreme case,” he said.

“The beaver dams themselves create great habitat … but when it poses a threat, then they have to be dealt with,” Choquette said.

ahead of the curve

Schoharie County’s dam inventory was welcomed by an official in adjacent Otsego County.

“I think it’s a great idea,” said Scott Fickbohm, manager of the Otsego County Soil and Water District.

“We have a similar interest in the location and condition of beaver dams,” he said.

While not planning a similar inventory, the district’s Upper Susquehanna Coalition, is planning to provide some human engineering help to a beaver colony at the northwestern edge of Otsego Lake, north of Cooperstown.

A long-existing beaver dam across a small stream in the town of Springfield regularly washes out because the beavers built it on soft ground and it’s not anchored as well as they usually are in more solid subsurfaces.

“It’s a double-edged sword,” Fickbohm said of beaver dams in general. “The dam serves a flood-control purpose, because they hold back water and release it slowly over three or four days.”

In the case of the dam near Otsego Lake, heavy rains increase water pressure in the pond and push the dam open, he said. Each year or so that sends water over state Route 80. It also sends muck and sediment into nine-mile-long Otsego Lake, according to Fickbohm.

A planned $15,000 coalition project expected to begin next month won’t strengthen the existing beaver dam, but is designed to control the flood and hold back sediment.

The plan is to install plastic sheets vertically in the stream below the beaver dam, Fickbohm said. Once in place, it should slow flood waters and block muck while giving the beavers time to put their own dam back together. The flooding from the weak beaver dam also increases potential risk from Giardia lamblia, a parasite sometimes carried by beaver and deer that sickens people drinking from untreated streams or water.

Otsego Lake is the source of the Susquehanna River, which supplies water for Cooperstown and ultimately empties into Chesapeake Bay in Maryland.

Categories: Schenectady County

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