Problem: Drought, Flash Flooding, Wildfire
Recommendation: Build constellation of small, water-slowing dams in seasonal waterways.
The extreme drought conditions that California is currently facing has sharpened the public’s understanding of the vital importance of water. Water is, indeed, life.
Ultimately, all of our fresh water is provided to us from rain or snow. The water in our rapidly-shrinking aquifers may have been stored underground for a few millennia, but it also originated from precipitation. Because the distribution of precipitation is decentralized and sporadic, happening mostly in our winter months, an essential approach towards conserving our water, replenishing our aquifers and reducing the destruction of both floods and droughts requires incorporation of concerted, decentralized water-conservation methods.
I was pleased to learn that California has begun piloting such decentralized water-conservation/ flood abatement techniques through the re-introduction of beaver, where appropriate, and mimicry of the beaver dams in areas where beaver reintroduction does not make sense. Unfortunately, this program appears to mostly be occurring the northern half of the State in several, apparently uncoordinated, efforts and it lacks the needed sense of urgency.
Beavers make small, leaky dams that allow rainfall and snowmelt to soak into the soil, replenishing our aquifers and buffering against drought. As we have seen first-hand in the decades following the extermination of the beaver in California, without the beaver, rainwater runs off the landscape rapidly, picking up soil as it picks up speed and thus causing destructive erosion, road washouts, silting of reservoirs and salmon streams and other mayhem. Because the water leaves the the area receiving rain so quickly, the soil is also more prone to drought and forests more prone to wildfire.
Large dams were built to retain water and prevent flooding. However, due to their infrequency and the large areas that are drained into them, rainwater can still pick up destructive steam over a large fraction of their upstream watershed before reaching the reservoir. Multiple, small, intentionally-leaky dams/ weirs that slow water at higher elevations are an important, complementary approach to our larger dams. Such a constellation of small, leaky dams would slow water before it had a chance to become destructive and would allow more of it to replenish our aquifers.
It is not hyperbole to say that the future of California depends on rapid improvement of our water management practices. A constellation of small, water-slowing dams are a critical component of such improvement.
I urge you to push for construction of a constellation of small beaver-mimicry dams and to reintroduce beavers to areas when it is sensible.
Anton Callaway, PhD.
Sources of additional information:
1. Brian Cluer, Ph.D., NOAA Fisheries, West Coast Region. 35th Annual Salmonid Restoration Conference. March 30, 2017. Davis, CA.
2. Emily Fairfax. California State University Channel Islands. https://emilyfairfaxscience.com/research/droughtbeavers/
3. Dave Schaub. Executive Director. Inland Northwest Land Conservancy. Spokane, WA. The New Yorker. August 15, 2022. p.3.
4. B. Stapleton & Michael M. Pollock, Ph.D. , NOAA Fisheries, Northwest Fisheries Science Center. 35th Annual Salmonid Restoration Conference. March 30, 2017. Davis, CA.
5. United States Department of Agriculture. Northwest Climate Hub. https://www.climatehubs.usda.gov/hubs/northwest/topic/incised-stream-restoration-western-us
6. Sarah Yarnell, Ph.D. (Presenter), Center for Watershed Sciences, University of California, Davis. 35th Annual Salmonid Restoration Conference. March 30, 2017. Davis, CA.
This chart appears in Groundwater: Ignore It, and It Might Go Away