An Ecological Treasure of International Importance

United in Our Efforts

The Lower San Pedro Watershed Alliance (LSPWA) is dedicated to uniting conservation minded individuals, groups, and agencies to protect a threatened riparian ecosystem and its supporting watershed.

Due to rapid growth in Arizona's Sun Corridor, the San Pedro River is the last remaining major natural and intact river ecosystem in southern Arizona. The lower San Pedro watershed has become the default repository for mitigation of impacts caused by this rapid growth.

By joining with the LSPWA, you help demonstrate that organizing at the watershed level is an important movement in the desert Southwest, one that transcends county and community boundaries. Together, let's ensure that this endangered landscape offers future generations far more than yet another land and water base for resource exploitation.

If you want to contribute to our legal effort to stop the proposed SunZia infrastructure corridor in the San Pedro Valley, send your tax-deductible contribution to LSPWA, PO Box 544. Mammoth, AZ 85618

A Significant, Singular Landscape

The San Pedro corridor has become the most important north-south migratory bird flyway within Arizona. The lower San Pedro watershed also harbors one of the richest remaining fish, reptile, amphibian, and mammalian habitats in the nation, and is the key to protecting several threatened and endangered species.

San Pedro River Flowing

A few of the many who call this place home:

Gila monster
Two birds perched on top of a saguaro skeleton
Bat flying at night
Desert Tortoise
Photos by Lon Brehmer

Imagine this spectacular watershed from the perspective of those who live here.

Because words are insufficient, please enjoy this short video. In it, you can clearly see that this stunning ecosystem—and the plants, animals, and landforms that comprise it—make a compelling case for conservation.

Latest News

Image of two book covers


Enjoy two new books about the San Pedro River valley.

Learn More ❯

Landscape view with the San Pedro flowing in the foreground

Comments Submitted

Read our statement on the new Waters of the U.S. (WOTUS) rule.

Learn More

Landscape view of mountains

Presentation by LSPWA

Peter Else discusses issues facing the San Pedro River in this presentation to the Sustainable Water Network.

Watch ❯

Our Programs

Collaborative Conservation

We outreach to diverse stakeholder groups and collaborate with other activist conservation groups.


We engage in administrative/legal efforts, and the development of educational materials.

Maintaining Conservation Standards

We monitor conservation easements and habitat conditions.

Creating a Bright Future Together with You

We are made up of allies, experts, activists, naturalists, artists, archaeologists, and donors, but anyone with an interest in protecting this special place is welcome to call themselves our member.


Thank you and credit to author Ralph Waldt for use of his phrase, "An ecological treasure of international importance." Thank you and credit also to Lon Brehmer for use of his photos throughout the site.