Wednesday, October 06, 2010
Lookin' A Little Parched
Copyright © 2010 Albuquerque Journal
By 2010 John Fleck
Journal Staff Writer
Water agencies are scrambling to find enough water to keep the Rio Grande wet through Albuquerque after the river dropped last week to its lowest level in six years.
The discussions reflect a new reality on the middle Rio Grande, as the Albuquerque Bernalillo County Water Utility Authority diverts increasing amounts of water from the river to provide drinking water for the metro area.
Last weekend's rain, along with the cooler weather, pushed the river back up over the weekend.
"It bought us some time," said Leann Towne, head of water management operations for the U.S. Bureau of Reclamation's Albuquerque office.
But the river has dropped again to unusually low levels, as the three major agencies responsible for water management in the middle Rio Grande work out details of an agreement to keep the river from drying up.
The deal is needed to meet requirements of the Endangered Species Act, which requires minimum flows under the Central Avenue bridge in Albuquerque to keep local populations of endangered Rio Grande silvery minnows alive.
The three agencies — the Bureau of Reclamation, the Middle Rio Grande Conservancy District and the water utility — will combine efforts to use water now stored in reservoirs upstream to keep the Rio Grande flowing, according to participants in the ongoing discussions.
"We all have an interest in meeting that flow requirement at Central Avenue," Towne said in an interview.
The agreement will allow the water utility to continue drawing its drinking water supply from the Rio Grande without violating Endangered Species Act rules. If the Rio Grande drops too much at Central, the river water diversion would have to be shut down, and the utility would have to get all its supply by pumping groundwater, said John Stomp, the agency's water resources manager.
That's where the utility previously obtained drinking water for the metro area. But in order to stop depleting the area's groundwater, the utility began diverting water from the river in 2008. The diversions have increased substantially this year.
Officials say there is sufficient water in upstream storage to keep the river flowing through Albuquerque over the next few months. Towne estimated it could take as much as 10,000 acre feet of water to keep the Rio Grande flowing in October — equivalent to the amount of water used by 20,000 to 30,000 typical households.
But water users are trying to balance the need for minnow flows with worries about next year's supply because of a forecast for a dry winter.
"The concern is conserving what they have now for next year," Towne said.
In a complex state-approved water accounting swap, the utility diverts both water imported into the Rio Grande from the Colorado River Basin and so-called "native water" at a dam near Alameda at the north end of town. Some of that water — after it has been treated at the utility's sewage treatment plant — returns to the river at the south end of town.
Between the north and south ends, those diversions mean less water flowing down the Rio Grande through Albuquerque.
But the effect on downstream users is also noticeable, said conservancy district hydrologist David Gensler. The district supplies water to farmers, and the water utility's operations have reduced the amount of irrigation water available at the district's Isleta diversion dam, Gensler said in an interview.
In recent weeks, the conservancy district has been releasing water from upstream storage dams for its irrigators. The water flows down the Rio Chama and Rio Grande to the diversion dams, where it is shunted into irrigation canals. But not all of the water has been making it all the way down the river to where the farmers need it, according to Gensler.
One area where water is being lost is the Albuquerque stretch, where historic groundwater pumping by the water utility and others has lowered the water table in areas flanking the river.
As a result of that past pumping, water literally leaks out of the river's bed into the ground below, said Nabil Shafike, a hydrologist with the New Mexico Interstate Stream Commission.