Oregon: The Beaver State

In colonial America, beaver fur was a high demand export. The pelt’s profitability as a hat-making material lured the French to present-day Canada. Simultaneously, hunting beaver paved the way to manifest destiny in the U.S, drawing trappers further west. In 1823, the Hudson’s Bay Company instituted its Fur Desert Policy. This agenda rapidly diminished the beaver population in what is now known as Oregon. At the peak of the fur trade, over 30,000 pelts were exported to Europe per year (1). Young offspring were regularly abandoned or killed. Near extirpation of the American beaver was a defensive move aimed at preventing colonizing fur trappers from encroaching on the area. At this time Oregon and Washington had not yet become part of the United States, and Hudson’s Bay Company aimed to keep it that way as a means to protect the more profitable resources of the north. Their plan did not prevent the U.S. from eventually incorporating the land in this region, but it did succeed in extinguishing beaver as a monetary source in Oregon and, unintentionally, eliminating the important ecosystem services which the beavers provided for the area essentially free of charge.

One of the primary reasons beavers construct dams is to evade predation in the resulting pools.

But what is a survival strategy for the beaver has cascading effects on the environment, not all intended by the fuzzy architects.

Beaver-built ponds keep runoff at higher elevations for longer so that the volume of water reaching lower elevations is more evenly distributed throughout the year. A dam series reduces the stream gradient, which reduces the power of the stream flows and the degree of erosion on channels. Less erosion means less sedimentation. Sediments instead settle into ponds, adding nutrients to the soil and often eventually becoming fertile meadows and bottomlands. Higher groundwater tables allow streams to run throughout the dry high desert in summer and support new plant growth and habitat that bolsters the integrity of the banks. A beaver dam’s ability to help reduce nitrogen from fertilizers and cattle waste in streams is of growing importance. All of this has varying effects on the animal and plant life of riparian habitat. For example, ninety-five percent of the land-based species living in Oregon’s Blue Mountains rely on riparian zones, and the beaver dams’ ponds act as excellent nurseries for aquatic species like salmon. With the decline of beavers all across North America, these benefits and more have been lost.

Beaver are no longer trapped at the dangerous rate they once were, but, unfortunately, many of Oregon’s streams lack the resources beavers need to make a comeback. Where woody plants are lacking, dams cannot withstand the flow of the currently incised stream, and there is no food to support the beavers through the winter. But without dams, the recovery of their habitat is difficult if not nearly impossible. No dams, no water. No water, no habitat. No habitat, no beavers, no dams.

Thankfully, there is a straightforward solution to this spiraling cycle: people can provide “a starter dam” for beaver. We call these structures “beaver dam analogs,” or BDAs for short.

Here’s how you build a BDA:

1. Pound a line of wooden posts into the ground using a hydraulic post pounder.
2. Weave branches and plant material between the posts to create a rough mimic of a beaver dam.
3. Add a few buckets of gravel and rock to plug up the bottom of the dam.
4. Let nature take over.

With time, debris naturally collects in the posts and branches. Sometimes flows are diverted, forcing the stream to cut into its banks, and it evolves from a straight canal to a twisting stream. This erosion supplies sediment to downstream dams and helps raise the stream bed. Eventually, the process reconnects the creek with its floodplain allowing for a healthy, more dynamic riparian environment. Sometimes beaver build their dams right on top of BDAs, other times they build nearby.

ONDA’s contribution

Since 2009, ONDA has built dozens of BDAs in the John Day, Malheur and Crooked River watersheds, working in close collaboration with the land managers in each of these regions.

While the work at Bridge Creek is definitely the best known in the state, one of the most rewarding projects is underway on Pine Creek Conservation Area. ONDA volunteers have spent a decade helping restore beaver habitat here. In 2015 volunteers constructed the first 15 BDAs on the creek. Within a year and a half, local beavers responded by outbuilding us more than 10 to one, and dramatically transforming and recovering entire reaches of the creek. This year, we will complete the final 30 BDAs on this creek, with high hopes for continued changes in the coming years.

Installing BDAs costs significantly less than traditional restoration methods, where large machinery is required to reconstruct sharply cut stream banks. And the lower price point isn’t the only advantage that BDAs have over other techniques.

As Ben Goldfarb, author of the new book Eager: The Surprising, Secret Life of Beavers and Why They Matter, told us, “ In our screen-dominated world, the opportunity to get out onto spectacular public lands, swing a sledgehammer, and work on behalf of nature is a rare and precious thing. Sure, using volunteers is cost-effective — but it’s also a chance to teach people about the value of beavers, fish habitat, and healthy aquatic ecosystems, and to cultivate a sense of stewardship in the next generation of conservationists.”

ONDA’s mission to conserve public lands and push for more areas to be protected as Wilderness helps beaver ecology as well. Stopping large-scale human interferences is often the most important, first step to recovery. Returning areas to their natural state is not simply for appreciating the intrinsic value of nature. Economists and scientists worldwide have begun recognizing the high price of ecosystem services. Global estimates put the value of ecosystem services in the trillions, and according to the BBC’s Earth Index, a single beaver can provide $120,000 worth of services (2). Every time we successfully secure more protected lands, we recover these services. When ONDA volunteers lend a helping hand through restoration projects, such as installing BDAs, we recover these valuable services sooner – and right now Mother Nature needs every extra minute we can give her.

Sources

1.   https://eh.net/encyclopedia/the-economic-history-of-the-fur-trade-1670-to-1870/
2.   http://www.bbc.com/earth/story/cost-the-earth-sources

Quick Facts

• Weighing in at an average of 65 pounds, beaver are the largest rodent in the U.S.
• The longest recorded beaver dam is 850 meters.
• Before colonization, an estimated 250 million beaver ponds covered what is now the U.S. This many dams could hold back enough water to submerge Washington, Oregon, and California.

About the author

Shea Stobaugh is a frequent ONDA volunteer, both in the office and in the field. She graduated from the University of Iowa with a degree in environmental bioscience and geographic information services. She is interested in gathering geographic information in the field to help further environmental goals and passionate about encouraging politicians to address environmental issues.