Water flows to Colorado River Delta

Fresh infusions of water reached a key Colorado River restoration site in Baja California this week as part of a bi-national effort aimed at reviving the river’s few remaining natural areas in Mexico.

The 750-acre site is part of a riparian area in the Colorado River Delta known as Laguna Grande that has been the subject of restoration efforts since 2008. The arrival of the flows come two weeks after the launching of a “pulse flow” at the U.S.-Mexico border that aims to simulate flood conditions and allow seeds to germinate.

The flow consists of the delivery of 105,000 acre-feet of water — enough to supply about 200,000 households for a year — over an eight-week period. The high-volume pulse flow is to be followed by a longer-term but less-intense base flow aimed at supporting the new vegetation.

The effort is part of a multifaceted five-year agreement between the U.S. and Mexican governments involving the Colorado River and known as Minute 319.

“We expect to have thousands and thousands of seeds germinating,” said Francisco Zamora director of the Colorado River Delta Legacy Program of the Sonoran Institute. The Tucson-based institute is leading the restoration efforts in Laguna Grande, an area of mesquite, cottonwood and willow trees that once flourished in the region.

Since the pulse flow was launched at the border on March 23 at Mexico’s Morelos Dam, there have been questions as to how far downstream the water would flow. Environmental groups hope that it will reach beyond the Laguna Grande and connect to the Rio Hardy, once a popular and hunting fishing area, and reach even farther to the Gulf of California.

As for Laguna Grande, “the water will reach maximum inundation” Wednesday or Thursday, Zamora said. “It’s flooding more areas than expected. There will be more potential area for natural germination.”