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by Franklin (Fred) Frank, Former San Luis Obispo Cal Fire and County Fire Chief, and Fire Captain at the Cal Fire Paso station

Overhead fire photo Courtesy of Joseph Wheaton (Utah State University) Creative Commons Attribution 4.0 International License.

As the former San Luis Obispo Cal Fire and County Fire Chief, and Fire Captain at the Cal Fire Paso station, I responded to many fires in and near the Salinas River. We saw the river as a nuisance, a threat and/or a firebreak, depending on location and conditions.

Then a friend introduced me to the beavers in the river near Atascadero. As an old fireman, I was impressed by how beavers greatly reduce the fire hazard in the river. I’ve seen several beaver ponds that are more than a hundred feet wide and many times that length. By building dams and channels that radiate out from the pond into fields, beavers back up water and hold it on the land, promoting growth of fire-resistant riparian vegetation in the riverbed that is a significant barrier to fire.

Under extreme burning conditions, fires can jump several hundred feet or more in front of the main fire. Beaver ponds and green vegetation are of great value on the flanks of fires burning under extreme conditions.

Cities along the river face a difficult, complex problem with fire in and around the riverbed, exacerbated by homeless occupancy. However, during one public discussion, I was surprised to hear managers say that beaver occupancy is also a problem. It was difficult for me to see the slides showing their fuel management plans. Cities would benefit from fuel management work along the river if carefully planned and supervised.

I spent several years providing technical advice on watershed and fuel management in Cal Fire’s coastal region and can offer some suggestions:

• Remove dead and dying trees and brush along the river banks. This would assist firefighters by reducing potential for spread and providing better access.

• Minimize heavy equipment use, because disturbance of riverbanks leads to serious stream bank erosion. Vegetation within the river channel helps reduce the velocity of the flow, therefore reducing erosion potential.

• Remove very little vegetation within the riverbed, and target highly flammable invasive species such as phragmites and arundo reeds.

• Consult with a stream hydrologist during the planning of this work.

With climate change and COVID 19 adding complications to an already serious problem, City Councils are being called upon to make some critical decisions. The liability associated with river disturbance cannot be overestimated. I hope my suggestions will be helpful.

What’s the difference between a healthy stream and an unhealthy stream, and why does it matter? 

It may seem hard to tell if a river or stream is healthy. I always thought that if there was running water it was a stream, and that was that. But now that I’ve spent a lot of time in beaver-restored sections of the Salinas River, the difference is like night and day.

The healthy, beaver-filled areas have a crisscross of ponds and woody structures throughout, lush vegetation, and much more water overall. There are side channels dug by the beavers in many directions. Islands of sediment form and vanish with the flow of the river, and the whole area is just absolutely buzzing with life.

In short, healthy rivers and streams are messy.

A healthy, messy river meanders, recharging groundwater, lessening the intensity of floods, and creating a large area of wetland that won’t burn even in the most intense wildfires. The wetlands beavers create are among the most biologically productive ecosystems in the world, supporting hundreds of species: birds, fish, amphibians, reptiles, insects and other mammals.

Unhealthy rivers and streams are what most of us are used to in California. Land uses that extend right up to the bank create incised streams, which typically only have one channel for the water to flow. Because the water is forced to flow in a narrow channel, it flows much faster and ends up digging out the channel bottom. Over time, the channels get deeper and deeper until roots cannot reach the water they were once connected to. Most rain water that does fall rushes to the ocean with no chance of spreading onto the land – leaving a dry, dead, highly flammable riverbed and floodplain that is a fire hazard instead of a lush, green fire break. 

The good news is that if we give the incised streams some room, they can be restored to their healthy state and bring us the fire protection and water storage benefits that we really need.

Beavers are the experts when it comes to stream restoration, but humans can help too! All we need to do is mimic beavers by using natural materials to add structure and complexity to our incised streams. The structures slow the water flow and catch sediment, so over time with continually adding complexity, the river bottom builds back up and the stream becomes healthy once again.