Beaver Patrol – Worth A Dam

“Are you a good witch? Or a bad witch?”

heidi08 Beavers and salmon, Beavers and water, Beavers elsewhere, Creative Solutions, Who's blaming beavers now?, Who's saving beavers now? May 23, 2017

The “Beaver Patrol” in Juneau understands how beavers are important to salmon. It was started by our friends Bob Armstrong and Mary Willson years ago. But obviously beaver beliefs are still forming and changing up there, because the forest service isn’t so sure about them. The reporter still thinks they live in the dam, and even one of their volunteers needs to look up the word “Destructive” in the dictionary, I think.

Coho habitat destroyed by beaver dam dismantler

Last summer was a great year for coho salmon returns to Dredge Creek. Unfortunately, salmon redds in the creek below Dredge Lake have been negatively impacted by someone it appears was trying to help them, says the Beaver Patrol.

The “Beaver Patrol” is a group of volunteer Juneau naturalists and concerned citizens who have been working in the Dredge Creek and Dredge Lake area — U.S. Forest Service Land — for about five years. They and the Forest Service manage the dams and have improved salmon habitat in the stream, said member Chuck Caldwell.

Another factor helping Dredge Creek’s coho rearing? Beavers.

Caldwell had taken note of three different redds — nests of pebbles where salmon deposit their eggs — just above a beaver dam. A fourth was outside the main channel and needed a nearby dam to maintain its water depth. The destruction of the dam lowered the water and this winter that area froze, he said.

“He was tearing (the dams) out once or twice a week. Clearly he just hated beavers. He also wanted to dig in the stream to make a nice, deep channel. He dug through two of the redds,” Caldwell said.

The digging and the dismantling of the dams destroyed all the salmon redds he had observed in that area, Caldwell said.

In the first half of November, Beaver Patrol member Jos Bakker ran into and confronted the man when he was in the process of destroying a dam. The man doesn’t appear to have come back after that, but the damage was already done, Caldwell said.

The Beaver Patrol emphasizes beavers’ positive impact on salmon rearing.

“If you look back a couple of decades, people used to think that if you got the dams out, the fish could move back easier,” Caldwell said. “That’s not the limiting factor in the coho population. The limiting factor is having a habitat the juvenile cohos can live in.”

“By and large, it’s a safe bet that beaver dams do provide excellent coho rearing habitat,” Schneider said. “They can cause major problems for adult cohos to access fish habitat, and that’s probably what gets most folks in the public tempted to tear out dams. It has to be a fine balance, like anything else … In a normal setting, you would have these major flood events on occasion. It would rearrange them and keep them in check. You’re not going to get that in Dredge. On top of that, there are not normal predator levels that you would find in a normal wild setting.”

Dams’ impact on adult salmon in a setting like Dredge is something about which the Beaver Patrol and the Forest Service are not in complete agreement. Member Mary Willson says 90 percent of the time beavers are actually helpful to coho populations. Schneider disagrees.

When he and the cub scouts notch the dens, they use specific techniques and tools to ensure muddy debris doesn’t end up covering redds.

Beaver management does require a balance, Miller said.

It’s one of those interesting situations,” he said. “It’s true that habitat is being created, but at the same time, beavers are very destructive.”

In areas where beavers might create an aesthetic issue, the patrol has put a cloth around the trees that will keep the beavers from gnawing them, Miller said.

In my old days back before my time as a psychologist we used to call that “they’re good, they’re bad, they’re really good, they’re really bad” kind of messaging ‘schizophrenogenic’. Meaning if it kind of makes you crazy. Of course now they no longer think schizophrenia is caused by parenting BUT I would argue the term still applies to beavers. Just look at the dedication of folks in a very small area on both sides of the fence. Bob Armstrong even got the forest service to bring out Mike Callahan to talk about flow devices in 2009, but they never let him install one. The breadth of understanding of beaver benefits there is razor thin. But still a lot thicker than some places.

Here’s what Michael Pollock said to me in our podcast interview. “Does some particular beaver dam ever prevent some particular salmon from getting over at some particular time? Sure. But that’s asking the wrong question”.

Beaver dams are doing so much good for so many salmon it balances out.

Here’s my own unscientific variation: “Do people ever get hit by ambulances? Of course they do. Does that mean we shouldn’t have ambulances? Absolutely not.”

mendenhall — Beaver Dam at Mendenhall Glacier: Bob Armstrong

Report from the Beaver Patrol

heidi08 Beavers and salmon, Beavers elsewhere, Creative Solutions March 17, 2014

Remember the story out of Juneau about a beaver patrol protecting Dredge creek and worrying because the beaver dams were ripped out? Well, it turns out a member of that patrol (Patricia O’brien) is a friend of the beaver management group on facebook and she sent us this:

Background

Dredge Creek runs through a U.S. Forest Service recreation area adjacent to a residential neighborhood. The creek heads near the Mendenhall Glacier Visitors’ Center. From its headwaters to Dredge Lake is only about one mile. Downstream from Dredge Lake it runs only about a third of a mile before emptying into a small holding pond before joining the Mendenhall River. Dredge Creek features coho salmon, Dolly Varden char, and cutthroat trout.

Beaver dams exist throughout Dredge Creek’s length. However, those dams have the potential for flooding trails. Below Dredge Lake, major trails are near the creek and the elevation of the trails is only slightly higherthan the creek. This area is heavily used by hikers, and dog walkers. Above Dredge Lake much of the terrain is rugged, and the area sees fewer hikers.

For about five years the U.S. Forest Service has agreed to allow a volunteer group (the Beaver Patrol) to work inthe recreation area. Additionally, a Boy Scout Weblos troop works with the Beaver Patrol, and the troop does most of the work in the creek above Dredge Lake. Except for months when ice limits beaver activity, the Beaver Patrol works in the area twice each week, and sometimes more. A goal of this partnership is to manage water levels to minimize trail flooding, while maintaining much of the habitat provided by the beavers. The Beaver Patrol has built; and maintained devices; to control water levels, even if beavers continue to add material to their dams. Where fish migration is encouraged, those devices are designed to allow fish to pass.

Excellent resource from Chuck! Thanks for putting this together. Every part of this is worth reading, but I especially liked this.

Obstructions to Migration

The first reaction for many viewing salmon in a stream with beavers is that the dams must be blocking salmon migration. Yet salmon have spawned upstream from several beaver dams in many watersheds for thousands of years. Often salmon may be seen mingling below a beaver dam until after a rain raises a stream’s level. One article commented that coho had no problem getting past beaver dams that were as high as two meters.Other articles observed no problems with coho getting past beaver dams. Steep steam banks allow beavers to build a much higher dam. Intuitively, it seems shallow water immediately downstream would make it more difficult for coho to jump over a beaver dam. Deeper water below an obstruction should enable coho to more easily jump over it. The higher the obstruction the deeper the takeoff pool should be. While the studies reviewed for this article did not cover this topic, the Beaver Patrol routinely clears material that would reduce the depth of areas below obstructions in Dredge Creek.

And what are their conclusions about beavers and salmon?

Conclusions

Pools created by beaver dams provide tailout areas preferred by coho for spawning. Since the Beaver Patrolclears impediments to fish passage twice each week when Dredge Creek in not frozen, it is unlikely that

spawning habitat will be a limiting factor to coho populations in Dredge Creek unless:

-people destroy redds after coho spawn

– construction causes sediment cover or otherwise degrade potential spawning habitat, or

– pollution degrades water quality.

Beaver ponds add summer coho rearing habitat in Dredge Creek. At least as important, by increasing water temperature and slowing stream velocity, beaver dams improve the winter survival of coho salmon in DredgeCreek.

Oh yeah, I guess that crazy researcher from the rogue agency NOAA has been right for all these years.

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Bonus points this morning: Best. Headline. Ever.

Say it ain’t so, Mr. Beaver!

A Reminder: Beaver Dams Protect Salmon

heidi08 Beavers, Beavers and salmon, Beavers elsewhere, Creative Solutions March 14, 2014

Coho habitat destroyed by beaver dam dismantler

Another factor helping Dredge Creek’s coho rearing? Beavers.

In late October of last year, the Beaver Patrol became aware that someone was destroying the dams in Dredge Creek between the holding pond and Dredge Lake.

Caldwell had taken note of three different redds just above a beaver dam. A fourth was outside the main channel and needed a nearby dam to maintain its water depth. The destruction of the dam lowered the water and this winter that area froze, he said.

This is a nice reminder from Juneau that beavers help salmon and people who rip out beaver dams hurt salmon. (Just in time for the salmonid conference, and I hope everyone attending reads it.) If I had my way every person in the hemisphere would read it, and probably a few in Scotland.

The Beaver Patrol emphasizes beavers’ positive impact on salmon rearing.

“By and large, it’s a safe bet that beaver dams do provide excellent coho rearing habitat,” said Schneider. “They can cause major problems for adult cohos to access fish habitat, and that’s probably what gets most folks in the public tempted to tear out dams. It has to be a fine balance, like anything else … In a normal setting, you would have these major flood events on occasion. It would rearrange them and keep them in check. You’re not going to get that in Dredge. On top of that, there are not normal predator levels that you would find in a normal wild setting.”

I want a beaver patrol! How do we get a beaver patrol? My guess is that this is the off shoot of the group of folks started by Bob Armstrong who dismantled dams in Mendenhall Glacier State Park so that the rangers wouldn’t have to exterminate to control flooding. He made sure that Mike Callahan came out and did a field assessment for them. The Tongass forest isn’t that far away, so I’m guessing these groups are related.

Something they do agree on: even when dams are at a level at which they may impact adult salmon, that’s no reason to rip one out. That’s where people like Beaver Patrol member and Cub Scout leader Scott Miller come in.

Miller is leader of Mendenhall River Community School Cub Scout Den 1, Pack 7. He and the cub scouts, also Beaver Patrol members, have been helping to open fish passage in the upper dams above Dredge Lake for the last five years.

Some of the redds in that area may have fared better, as the dams weren’t destroyed, Caldwell said.

Miller said he’s seen coho clear a six-foot dam when the water is high. “They definitely can jump if they can get a deep enough pool below,” he said.

If we learn anything about beavers and salmon it will happen in Alaska first, where there are four species of salmon in massive supply and the entire economy hinges on their life cycle. That’s where Michael Pollock started his research and where people really started to see that beavers make the difference to population numbers. People in Alaska are really really smart about beavers. Maybe I should move there.

Beaver management does require a balance, Miller said.

It’s one of those interesting situations,” he said. “It’s true that habitat is being created, but at the same time, beavers are very destructive.”

Sigh. Never mind.