Lower Ditch

Engineered riffles are good for irrigators and fish

About the Project

The Gila River runs from its headwaters in Southwest New Mexico and joins the Colorado River at Yuma, Arizona. The Gila was named America’s Most Endangered River in April 2019, largely due to threats of climate change and new irrigation diversions. Its 60,000 square mile watershed provides sustenance for abundant wildlife.

The Gila River has sustained the agricultural community in the Cliff-Gila Valley for 140 years. Push-up dams—typically a plastic-lined pile of gravel stretching across the stream—direct water into three irrigation ditches. This approach changes river flows, increases water temperatures, and blocks essential access to prime habitat in the Gila Wilderness Area, which lies upstream.

The Nature Conservancy (TNC), the Gila Basin Irrigation Commission, and others are working to replace the two largest push-up dams with engineered riffles in the stream bed. These contours are better for fish, allowing base flows to stay in the river and sediment to move more freely. The riverbed contours are shaped in ways that efficiently divert water for irrigation purposes. TNC partnered with irrigators and local landowners to identify water management solutions in the Cliff-Gila Valley that reduced the need for a proposed permanent downstream dam that would have significantly altered the Upper Gila. Successful implementation of the engineered riffles will serve as a model for improving diversions on other streams in New Mexico. With over 600 outdated and poorly functioning diversions in New Mexico, this partnership can serve as a cooperative model for other river systems.

FACTS AT A GLANCE
Owner: Private landowners
Size: Two pushup dams crossing the river
Project Cost: $1,075,000 for each dam
ORF Investment: Design
Miles Opened: 1 mile
Fish: spikedace, loach minnow
Status: Design and permitting work underway


OUTCOMES
  • Rewater one mile of the stream corridor
  • Improve habitat supporting two listed fish species and two listed bird species, among others
  • Improve efficiency and reduce diversion costs with modernized infrastructure
  • Model effective partnership between irrigators and a conservation organization to help New Mexico move beyond the outdated farms versus fish paradigm
  • Expand fishing opportunities and recreational tourism

Project Partners

Gila Basin Irrigation Commission

New Mexico Interstate Stream Commission

The Nature Conservancy

Natural Resources Conservation Service

Land and water owners in the Cliff-Gila Valley

New Mexico Acequia Association

Audubon New Mexico