Wetland unaffected by Yuma desalination discharge
The 2010-11 pilot operation of the Yuma desalination plant in Arizona near the Mexico border caused no significant environmental effect to the Ciénega de Santa Clara, the largest wetland on the Mexican portion of the Colorado River Delta, a research project has found.
A pilot run of the Yuma Desalting Plant (YDP) from 3 May 2010 to 26 March 2011 used some of the water that normally flows to the ciénega to provide desalinated water to the Colorado river and added saline reverse-osmosis effluent to the Bypass Drain, which brings agricultural wastewater to the ciénega from the US.
To ensure that the ciénega would continue receiving the same amount and quality of water as before, US and Mexican government agencies and non‑governmental organizations from both sides of the border worked together to provide ~30,000 acre-ft (37 million m³) replacement water to the ciénega during the May 2010 to March 2011 pilot run of the Yuma plant.
A binational program led by the University of Arizona was established to monitor environmental conditions in a ~6,000 ha area characterized by emergent vegetation and associated open water areas around the termini of the Bypass Drain and the Santa Clara-Riito Drain, which bring agricultural runoff to the ciénega from Mexico.
Monitoring began in December 2009 and extended to June 2011 - from approximately three months before until three months after the pilot (33% capacity) operation of the YDP. Data from smaller-scale monitoring efforts that began in August 2006 were also used in this study.
The short-term changes associated with the pilot operation of the YDP, with the arranged extra water, did not cause significant changes to the features of the ciénega monitored during the period of this study.
"The Ciénega de Santa Clara appears to be an ecosystem that is resilient in the face of short-term disturbances and minor changes in water quality and quantity, minor changes in drainage resulting from earthquakes, and fire," concludes the report.