Gravel pits could help LCRA with water supply
GARWOOD (AP) — A pair of old gravel pits on the fringes of this South Texas town may spell the future of water supplies in the Colorado River basin.
Here, in the midst of rice country, the Lower Colorado River Authority is six months into a project to figure out whether it can call on its vast network of canals, which stem like capillaries from the river, to store water in the lower part of the basin.
After a record drought, one that frequently pit Austin-area residents against downstream farmers over increasingly precious water, the LCRA is trying to come up with new ways to capture water collecting downriver.
Adjacent to the canals, originally built to flood rice paddies in the Garwood area, the land is pockmarked with gravel pits. In April, the LCRA inundated two of these pits, depleted decades ago, with more than 2,000 acre-feet of water. An acre-foot roughly equals the amount of water three Austin households use each year.
The ongoing pit project, which covers about 150 acres, is a prelude to a much more ambitious plan to build as many as three reservoirs in the lower basin, each of which could store roughly 20,000 acre-feet of water. The reservoirs, which would capture rainwater that falls south of the Highland Lakes, could alleviate the strain of serving farmers downstream of lakes Travis and Buchanan, Central Texas’ major reservoirs.
“It’s about avoiding having to release stored water by using existing infrastructure,” said Kyle Jensen, executive manager of external affairs at the LCRA.
The LCRA reports that this year alone, one in which releases for rice farmers were heavily curtailed, about 800,000 acre-feet of water has flowed over the Bay City dam on the Colorado River near the Gulf Coast.
Much of that is due to rainfall below the series of dams that form the Highland Lakes.
By comparison, lakes Travis and Buchanan currently hold 884,000 acre-feet of water.
Under the reservoir plan, the LCRA would divert some of that rainfall through its canals to the reservoirs, which could refill several times during the year.
The gravel pit pilot project has cost about $150,000 thus far. The chief cost is the $17,000-a-month rental costs of a trio of diesel pumps that can shoot 16,000 gallons of water a minute from the reservoir back into the canal system.
Lehrer Interests, the company that has long owned the land and is also intimately involved in Garwood’s rice operations, is providing the old gravel pits for free.
“Let’s try and do something with these gravel pits we’ve got,” said Ralph Savino, Lehrer’s chief executive officer.
For generations, miners have dragged up the thinly buried rock, which was beaten up and deposited by millennia of river action. Over several decades, deposits of silt appear to have more or less sealed the gravel pits being used in the LCRA project.
Like giant puddles, they carried a depth of 5 to 15 feet of water at any given time — enough to be home to bass, catfish and alligators.
Now flooded, they’re as deep as 50 feet, said Mike Shoppa, LCRA’s manager of irrigation operations.
Since April, LCRA has steered 5,500 acre-feet of water into the gravel pits and pumped out 3,000 acre-feet.
Jensen said the pilot project could turn into a “permanent endeavor.”
“It’s a cost-effective way to impound water,” Jensen said.
Savino hopes the LCRA expands the project to other gravel pits. He estimated that about 1,800 acres of depleted gravel pits are near canals in the Garwood area. Mining on one 640 acre-tract will finish up in the next seven months or so, he said.
But LCRA officials say depleted gravel pits must be situated just so to qualify them as potential spots to store water, ruling out many old pits.
In contrast to the generally flat surroundings, current and old mining operations reshape the earth into a wavy landscape of sandy cliffs and dugout basins.
Rice can’t grow on the oddly shaped land, and the slopes are too steep to safely run cattle.
“There are plenty of gravel pits that are good for nothing,” Savino said. Left behind after mining operations wind down, the pits “don’t cost you anything to make them,” he said.