San Antonio ditches to carry water for Bosque birds this winter
Middle Rio Grande Conservancy District irrigation ditches are carrying drainage water from just above Brown Arroyo east of Socorro to the Bosque del Apache National Wildlife Refuge south of San Antonio this fall and winter as a result of an agreement between the two entities that took effect after the regular irrigation season closed Nov. 1.
The water is being taken from the Riverside Drain by Brown Arroyo and put into the San Antonio canal for delivery to the refuge.
“We’re not diverting water. The drains run all year long; it’s just groundwater,” said MRGCD Socorro Division water master Lorenzo Benavidez. “We’re just diverting it into to the San Antonio ditch instead of letting it go back into the low flow. We usually dump the drain into the low flow at the Brown Arroyo. Either way, it’ll get back into the low flow.”
The rock-lined low flow channel parallels the Rio Grande from San Acacia dam to the Elephant Butte Reservoir, and was built by the U.S. Bureau of Reclamation in the 1950s to deliver river water to the reservoir more efficiently, but hasn’t been used in that capacity since 1985, according to a 1999 report by Bureau engineer Chris Gorbach. Now, it is the valley’s main drainage ditch, collecting seepage and irrigation outflows that are returned to the river and eventually to the reservoir. It is the refuge’s primary source of water, and supplements the district’s irrigation supply during the growing season.
The refuge has always used ground water collecting in drainage ditches and the low flow channel during the winter to flood ponds for wintering waterfowl, according to refuge manager Kevin Cobble, but until this year, pumped the water from ditches on the refuge. By using gravity to convey the drain water to the refuge in MRGCD irrigation ditches, the refuge saves the costs of pumping, and allows more efficient flooding, especially of the ponds west of U.S. Highway 1.
“In the past, we’ve always had to pump to keep some of our units on the west side full,’ he said. “MRGCD is collecting some drain water, and sending it down the San Antonio ditch, and runs one of our ditches to us. It requires a little extra work on their part to run the water.”
MRGCD hydrologist David Gensler said the refuge got a little behind schedule this fall because of the federal government shut down and equipment problems and asked the district for help. Because the ditches were available, it was no problem.
“There was almost no pond filling done in October,” he said. “They got very behind schedule in their flooding. We normally don’t have water running down there, so it’s no problem picking up the drain water. We didn’t have any winter construction planned in the San Antonio lateral, no structures to build or anything to do. It doesn’t hurt anything.”
To be sure the action didn’t affect any water agreements with downstream users, Gensler cleared the plan with the Interstate Stream Commission beforehand. The refuge has water rights on its valley land, permitting the use of water for farming and other purposes, he said.
Not having to pump is a bonus.
“It saves the taxpayers money, and makes us better able to manage water for the birds,” Cobble said.
A record-breaking number of ducks and geese are wintering at the refuge this year, so having flowing water in the ponds is critical.
“I think right now, we have some of the biggest bird populations we’ve had in a long time or ever had,” he said. “We have some fairly big units that are difficult to flood otherwise. A little bit of flow is best way to control disease, to continually bring in water.”
Benavidez has ordered district workers to lock all the metal check dams in the ditches in the up position to prevent water levels from rising.
“We’re not allowed to let anyone irrigate,” he said. “That’s why we locked all the checks up. Somebody could run by there and close a check. We’re worried about someone breaking a ditch during the night.”