{"id":10676,"date":"2014-10-09T13:03:19","date_gmt":"2014-10-09T17:03:19","guid":{"rendered":"https:\/\/esa.org\/esablog\/?p=10676"},"modified":"2014-10-09T13:03:19","modified_gmt":"2014-10-09T17:03:19","slug":"river-flow-by-design-environmental-flows-support-ecosystem-services-in-rivers-natural-and-novel","status":"publish","type":"post","link":"https:\/\/esa.org\/esablog\/2014\/10\/09\/river-flow-by-design-environmental-flows-support-ecosystem-services-in-rivers-natural-and-novel\/","title":{"rendered":"River Flow By Design: Environmental Flows Support Ecosystem Services In Rivers Natural And Novel"},"content":{"rendered":"

The October 2014 issue of ESA\u00a0Frontiers<\/em>\u00a0spotlights river management in the Anthropocene<\/h2>\n

\u201cDawn on the Delta was whistled in by Gambel quail, which roosted in the mesquites overhanging camp. When the sun peeped over the Sierra Madre, it slanted across a hundred miles of lovely desolation, a vast flat bowl of wilderness rimmed by jagged peaks. On the map the Delta was bisected by the river, but in fact the river was nowhere and everywhere, for he could not decide which of a hundred green lagoons offered the most pleasant and least speedy path to the Gulf. So he traveled them all, and so did we. He divided and rejoined, he twisted and turned, he meandered in aswsome jungles, he all but ran in circles, he dallied with lovely groves, he got lost and was glad of it, and so were we.\u201d<\/p>\n

-Aldo Leopold, \u201cThe Green Lagoons<\/a>,\u201d A Sand County Almanac with Essays on Conservation from Round River<\/em>. Oxford University Press 1966. pp 150.<\/p>\n<\/blockquote>\n

For Aldo Leopold, an adventure that shone in memory could not be revisited in life without losing its luster. \u201cFor this reason, I have never gone back to the Delta of the Colorado since my brother and I explored it, by canoe, in 1922,\u201d he wrote in his 1944 account of the trip, \u201cThe Green Lagoons.\u201d By then it was already too late to go back; the delta was dying. The Hoover Dam and and Imperial Valley projects already sat over the river upstream, delivering power and water to California, Colorado, and Nevada, and holding back the water, silt, and spring floods that had created the rich density of delta life he remembered. That year the United States and Mexico signed a treaty <\/a>for the \u201cUtilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande\u201d that allocated 90 percent of the river\u2019s water to the States, 10 percent to Mexico, and none to the delta. Today, the river supports 40 million people, but not the old ecosystems of its lower reaches.<\/p>\n

Last spring, the Colorado River reached its delta for the first time in 16 years, flowing into Pacific Ocean at the Gulf of California after wetting 70 miles of long-dry channels through the Sonoran Desert. The planned 8-week burst of water from Mexico\u2019s Morelos Dam<\/a> on the Arizona-Mexico border was part of a pilot program included in the Minute 319<\/a> amendment to the 1944 treaty,\u00a0 the culmination of years of diplomatic negotiations between the U.S. and Mexico and campaigning from scientists and conservation organizations<\/a>. Now ecologists wait to see how the short drink of water will affect the parched landscape.<\/p>\n

Tides flow backwards up the dry channels of the Colorado River delta, as seen in an astronaut photo taken June 21, 2013. Prior to the construction of the Hoover Dam and other large water projects on the Colorado, the delta estuary supported a great diversity of species in 3,000 square miles (7,700 square kilometers) of braided channels and lagoons. Now, the riverbed often dries not far from the Arizona-Mexico border. In the spring of 2014, an experimental \"pulse\" of 105,000 acre-feet (130 million cubic meters) of water were released from the lowest dam on the river in an effort to recover some the lost services provided by the lower Colorado ecosystems. <i>Credit, NASA.<\/a>

Tides flow backwards up the dry channels of the Colorado River delta, as seen in an astronaut photo taken June 21, 2013. Prior to the construction of the Hoover Dam and other large water projects on the Colorado, the delta estuary supported a great diversity of species in 3,000 square miles (7,700 square kilometers) of braided channels and lagoons. Now, the river typically runs dry a few miles south of the Arizona-Mexico border. In the spring of 2014, an experimental \u201cpulse\u201d of 105,000 acre-feet (130 million cubic meters) of water was released from the lowest dam on the river in an effort to recover some the lost services provided by the lower Colorado ecosystems. Credit, NASA<\/a><\/i>. (Click image to enlarge it).<\/p><\/div>\n

This year\u2019s spring pulse held less than 1 percent of the volume of the Colorado\u2019s annual spring floods before the construction of ten major dams and diversions to municipalities, industry, and agriculture. A return of the lush Colorado delta of the 1920s will not be possible. But there is hope that periodic flows will bring back willow, mesquite, and cottonwood trees, revive insects and dormant crustaceans, give respite to birds migrating on the Pacific Flyway, and ease strains on fisheries in the Sea of Cortez (Gulf of California).<\/p>\n

\"The<\/a>

The Colorado River runs dry on the U.S.\/Mexico border 2 miles below the Morelos Dam. Credit Pete McBride, USGS<\/a><\/i>.<\/p><\/div>\n

Learn more:<\/p>\n