Organic hydro-engineering

We arrived in California in the fourth year of the drought. It didn’t rain often last winter but when it did it poured, and the Santa Rosa Creek — which had been trickling through our neighborhood — became a torrent. As I watched all that precious rainwater rushing away to the Russian River, and thence to the Pacific Ocean, I wondered: What’s California doing to capture that water? The answer so far seems to be: Not much.

The need for large-scale water storage has been long discussed, but (at least from my newcomer’s perspective) not seriously considered until the recent crisis. The picture worth a thousand words was of Governor Jerry Brown examining bare ground in the Sierra Nevada Mountains last March. That ground should have been covered with deep snow.

Here in Santa Rosa, a friend who runs Atlas Coffee has taken matters into his own hands. He acquired the 500-gallon storage tank shown here:

Since that photo was taken, he’s hooked it up to a pump. Rainwater flows off the roof, it’s pumped into the tank, and then it irrigates the plants. It’s a wonderful idea that I’m sure has occurred to other homeowners and businesspeople, but you don’t see many other implementations around town. And as El Niño approaches, other priorities will understandably loom larger. Hydro-engineering projects, even relatively simple ones like this, are daunting. And the problem really needs to be addressed at much larger scale.

On that larger scale we still tend to imagine hydro-engineering projects, bigger ones like raising the height of the Shasta Dam to the tune of $1.2 billion [High Country News]. That sounded plausible to me. Then, last night, I watched a PBS documentary on beavers. I’m a sucker for nature documentaries, and I’ve missed seeing beavers since moving to California, they were everywhere in New Hampshire, so it was fun to watch them in action. Then this segment grabbed me:

Here’s a bit more of the backstory. In the Susie Creek watershed near Elko, Nevada, the land’s been drying out since cattle began grazing it 200 years ago. Beavers, reintroduced recently, reversed that trend. In this post, the Resilient Design Institute’s Alex Wilson refers to the same clip I quoted above:

The excellent 2014 PBS Nature documentary Leave it to Beavers describes how beavers modify the landscape to retain moisture. It turns out that beavers don’t only create ponds by damming creeks, the excavate ponds deeper, allowing them to hold more water. Biologist Glynnis Hood, Ph.D., who has been studying beavers near Edmonton, Alberta, described how important a role beavers play in Alberta by holding water.

“In 2002 we had the worst drought on record,” she reported. “The only places where we had water in natural areas was where we had beaver, and farmers were actually seeking out neighbors who had beavers on their landscape to water their cattle. So with beavers back on the land, even during the worst drought on record, they were mitigating the effects of drought and keeping water on the landscape.”

That idea was echoed in the PBS documentary by hydrologist Suzanne Foudy, Ph.D., of the U.S. Forest Service in describing the impact new beaver arrivals have been having on Susie Creek in north-central Nevada, near Elko. “If the snowpack’s coming off earlier and ranchers want water,” she said, “then we’ve got to figure out a way to keep it on the landscape, because it’s no longer going to be stored as snow in the mountains.” She continued: “What beavers do in all these itty-bitty streams is they create these small savings accounts, these pockets where it’s stored — no longer as snow, but as surface and groundwater.”

I’ve always enjoyed watching beavers and thinking about their effects on my local environments. But I never realized that the species as a whole can provide a critical ecosystem service at large scale. Here’s hoping that California will recruit them to help us replace a dwindling snowpack with water stored on the land. And that, as a bonus, I’ll get to see them more often again.