Walking & Mapping the San Pedro's Flows

“This is participatory science at its best. It connects people to this river in a real way.”

-Holly Richter, The Nature Conservancy's Arizona Director of Conservation

Annual San Pedro River Wet/Dry Mapping

Armed with GPS technology, more than 150 volunteers, conservationists and agency staff spend the third week of June measuring where water is present on the San Pedro River. This ongoing monitoring project provides insights into the health of this premier southwestern river system.

Dozens of partners coordinate this massive effort that covers over 220 miles within the San Pedro River Basin.

In addition to local residents along the river, our partners in this effort include the Bureau of Land Management, Community Watershed Alliance of Benson, Friends of the San Pedro River,  Cascabel Working Group, our Mexican partners and landowners.

"This is participatory science at its best. It connects people to this river in a real way," said Holly Richter, the Conservancy's Arizona director of conservation. "Many people do this year after year because they love this river."

River Mapping Provides Important Information

Last year, 29% of the river miles mapped had surface water flowing. In 2011, 33% of the river overall continued to flow in late June before the monsoon rains began three years ago.


Mapping this river over time will provide insight into what causes reduction of river flows climate change, drought, groundwater or surface water withdrawals.

On the flip side, it can also tell us where our efforts to restore river flows, through reducing groundwater pumping or recharge of water into the underground aquifer, are making a significant difference. The effort will also assess the habitat for beaver, fish and other aquatic organisms.

Citizen Scientists

The Conservancy is grateful to all of the people who brave the heat to do this year after year. We asked our dedicated volunteers to share their experiences. What you read may inspire you to join the effort!

Share a cool experience. Jessica Hayes says “We came across more wildlife this year including a rattlesnake, coatimundi, deer and Gila monster. A storm started to roll in toward the end, which was nice.”

What are three adjectives that best describe this experience? Tom Dabbs replied “important, peaceful and educational.” Fellow citizen scientist Jennie Cure’ calls her experience gorgeous, important and interesting.

Why are you a part of this project? Steven Anderson says “I’ve been hiking the river since 1976 and I’ve seen a lot of change. I like being a part of it!”

How does it make you feel at the end of the day? James Mahoney says “Tired, thirsty and satisfied that this valuable work is being implemented over the years and into the future.”


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