The cienega currently receives about 107,000 acre-feet of agricultural runoff water per year. When the YDP is running, the cienega is projected to receive about 67,000 acre-feet of runoff plus about 10,000 acre-feet of effluent from the plant.
An acre-foot of water is 325,851 gallons - enough to support a family of four for one year, according to the Central Arizona Project.
"I think we've got a good idea of what the natural range of variability is," he said. "So the question now is: When one-third of the water gets taken out to go through the Yuma Desalting Plant and a salty brine starts flowing toward the cienega instead, how will that affect the health of the cienega?"
To answer that question, the researchers placed instruments that record water quality and water level every 30 minutes at 20 locations all over the cienega. Some instruments are in open water, some are along the edges of the marsh, and others are deep in cattail thickets.
Every month, the researchers use small boats to visit every instrument and download the information stored in it.
The team also measures water flow where the cienega's main sources of water, the agricultural canals known as the Bypass Drain and the Riito Drain, empty in the cienega.
The researchers assess the bird populations during the breeding season and during the spring and fall migrations. The team uses satellite images to measure the extent of the vegetation.
"We see the cattails green up in the spring and die back in the fall," Flessa said. "We're not sure if the seasonal variation in water level is because of agricultural water use north of the cienega or because of seasonal changes in water use by the cattails."
At the April meeting of the monitoring team, the researchers were able to see whether the April 4 Mexicali earthquake affected the cie
|Contact: Mari N. Jensen|
University of Arizona