The San Pedro River Beaver: Back to the Future

All photos copyright Bob Herrmann

Visit the San Pedro Riparian National Conservation Area (SPRNCA) almost any time of the year, and you have the chance to see nature’s aquatic engineer at work: the beaver. 

A beaver flips its tail in the San Pedro River. Photo credit: Bob HerrmannCurrently, a healthy and growing population of beaver calls the San Pedro River their home. Their dens and dams are seen within the Conservation Area.

Beaver haven’t always been around, though. Back in the 1880s, the San Pedro River was wide, shallow and slow moving. Hundreds of beaver ponds captured the flow of water and supported a healthy population of fish, water birds, and other animals. In fact, James Pattie, an American fur trapper of the 1820s named the San Pedro “Beaver River” for all the beaver he found  (and trapped) there. 

Decline and rise of the beaver population
Things changed rapidly once southeast Arizona became part of the U.S. In the 1870s, silver mills harnessed the river and built their own dams across the San Pedro. A series of devastating floods in the 1890s hastened “down cutting” of the river.  Downcutting is when a flood cuts down into the ground. The result is a deeper, narrower river channel. Most lethal for the beaver was a campaign to eliminate them by dynamiting their dams and dens in the 1880s to reduce the threat of malaria to the troops at Fort Huachuca.

It’s likely that the river’s beaver were gone by the 1920s. Formation of the SPRNCA in 1987 brought with it a federal mandate to restore plants and animals, including the beaver.

In 1999 the first beaver was reintroduced.  Over the next 13 years, a total of 15 beaver from California, Phoenix and other areas were released in the San Pedro.

Today, around 100 beaver call the upper San Pedro home.  In the areas they occupy, they build dams that hold back the flow of the river, allowing its water to seep in and replenish the underlying ground. The ponds encourage the growth of aquatic plants, fish, amphibians and turtles. They also provide a stopover for migrating waterfowl. 

Beaver dams along the river
Beavers are visible mostly early in the morning or in the evening.  More likely you’ll be able to study the elegant, useful reservoirs they erect.

When you visit the SPRNCA, stop by the San Pedro House Bookstore, operated by the Friends ofPhoto (c) Bob Herrmann the San Pedro River. The Bookstore volunteers will be glad to help you find the beaver dams, rare birds and the other natural wonders to be seen in the SPRNCA.

See an educational video about the beaver, produced by the Friends of the San Pedro and developed by videographer, Mike Foster:

To learn more, visit the Friends’ web site at You’ll also find information on activities and facilities available to SPRNCA visitors.

For more information on other wildlife watching opportunities in Cochise County, please visit our bird-watching page