Barriers Can Stop Beavers From Plugging Pipes

Barriers Can Stop Beavers From Plugging Pipes MISCELLANEOUS EQUIPMENT Pest Animals 34-4-25 Beavers are notorious for plugging up overflow pipes. Years of work and experimentation at the Noble Research Foundation have produced a beaver barrier that works. "We tried PVC pipe and electric fencing around outlet pipes, and it worked as long as the electricity stayed on," recalls Mike Porter, wildlife biologist. "However, every time it flooded, the debris had to be dealt with, and trees fell on the lines. We had more than 140 ponds on 12,000 acres, and it just wasn't practical to check ponds on a daily or even weekly basis." Once the electricity was gone, it was only a matter of time before the beavers were back. Porter began looking for more passive ways to control beaver activity. He settled on parallel steel bar barriers that encaged the pipe. The 1/2-in. to 3/4-in. bars are welded in a horizontal pattern with 1-in. gaps and vertical framing at the corners. This allows water to flow through and debris to float up and over the barrier as water levels rise. "We found that you needed a minimum size or the beavers would just build a dam all around it," says Porter. "If the box was at least 4 ft. by 5 ft. and the bottom was buried at least 6 in. into the earth around the pipe, it would minimize beaver damage." Boxes with bottoms could also be installed over the pipes, resting on the pipe itself or on posts driven into the soil around the pipe. Porter also found that if the riser or standpipe was at least three feet above surrounding soil levels, the beaver were less likely to try to build around it. Since beavers are drawn to flowing water, running a perforated pipe from near the bottom of the pond to the overflow pipe can minimize activity. Porter found this was also a way to defeat a dam built around a barrier. In those cases, the parallel bar barrier was modified to allow the pipe through to the overflow pipe. What doesn't work, says Porter, is trapping or hunting. "You can run them out of the watershed, and if it is beaver habitat, they will be back within 6 months to a year," he says. "Now we just try to live with them and prevent damage. We have parallel bar barriers that have been in place for 25 years and should still be there in 75." Porter has used two different types of barriers. One was built in a single unit, while the second was built in panels and assembled on site. Regardless of type, he emphasizes that they be larger than the overflow pipe and never less than 14 in. above the overflow pipe. "We've tried sucker rod and seen some built out of rebar," says Porter. "I've seen wire netting panels, hardware cloth and even livestock panels, but they all tend to clog up. It is the vertical posts in the panels that cause the clogging. The fewer of them you have, the less likely it will clog." Contact: FARM SHOW Followup, Mike Porter, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, Okla. 73401 (ph 580 224-6444; fax 580 224-6420; mdporter@noble.org; www.noble.org).

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