Green Lagoons No More
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Metadata
- Sensor(s):
- Landsat 8 - OLI
- Data Date: April 25, 2020
- Visualization Date: June 10, 2020
When conservationist Aldo Leopold first paddled the Colorado River Delta in 1922, he was awed by the delta’s seemingly endless maze of green lagoons. “On the map, the Delta was bisected by the river, but in fact the river was nowhere and everywhere,” he wrote in A Sand County Almanac.
The wildlife, especially, entranced him. “A verdant wall of mesquite and willow separated the channel from the thorny desert beyond,” he continued. “At each bend we saw egrets standing in the pools ahead, each white statue mashed by its white reflection. Fleets of cormorants drove their black prows in quest of skittering mullets; avocets, willets, and yellow-legs dozed one-legged on the bars; mallards, widgeons, and teal sprang skyward in alarm.”
If he were to return and see today’s Colorado River Delta, Leopold would likely be amazed by how much it has changed. With most of the river’s water diverted into an irrigation canal near the U.S. - Mexico border, about 90 percent of the wetlands are gone. The mesquite and willow have largely been replaced by invasive salt cedar. And most of those verdant lagoons have turned into salt flats. Without an influx of nutrients from the river, far fewer species live in the estuary and Gulf of California.
In the natural-color satellite image above, the dendritic tidal creeks that flow into the gulf and tidal mudflats look like spindly fingers reaching into the sea. White salt flats and brown, shifting dune fields of the Sonoran Desert flank the delta and Montague Island. The Operational Land Imager (OLI) on Landsat 8 acquired the image on March 20, 2020.
There are still a few pockets of green that Leopold might find familiar. One of the largest, the Ciénega de Santa Clara wetland, formed by accident in the 1970s when the United States built a canal that drained salty irrigation runoff from farmland in Arizona. As the new source of moisture poured into the desert, an oasis of reeds, cattails, waterfowl, and other types of wildlife grew up around it, turning it into one of the largest wetlands in the area. Today, 280 species of birds spend their winters there.
References
- Arizona Public Media (2019, April 10) As the Colorado River Basin Dries, Can an Accidental Oasis Survive? Accessed June 5, 2020.
- Arizona Republic (2020, April 20) How a trickle of water is breathing life into the parched Colorado River Delta. Accessed June 5, 2020.
- Audubon (2019, April 10) Water to Flow in Colorado River Delta Again. Accessed June 10, 2020.
- International Boundary and Water Commission (2018, November 28) Minute 319. Accessed June 10, 2020.
- NASA Earth Observatory (2014, May 1) A River Renewed. Accessed June 10, 2020.
- National Geographic (2013, April 2) The Accidental Wetland in the Colorado Delta. Accessed June 10, 2020.
- Western Washington University (2012, June 28) The Delta of the Colorado River. Accessed June 10, 2020.
- YaleEnvironment360 (2019, February 14) Restoring the Colorado: Bringing New Life to a Stressed River. Accessed June 10, 2020.
NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. Story by Adam Voiland.
This image record originally appeared on the Earth Observatory. Click here to view the full, original record.