Safety issues on Rio Grande dams raised

[SHANEA]

Safety issues on Rio Grande dams raised

Web Posted: 08/19/2007 11:47 PM CDT
Anastasia Ustinova
Express-News

None of the four dams that regulate the Rio Grande between Del Rio and the Gulf of Mexico are completely safe, but they should be able to withstand a major storm surging through South Texas, according to a recent report by the International Boundary and Water Commission.

Inspectors classified the four dams — Amistad, Retamal, Falcon and Anzalduas — as either "potentially unsafe," "conditionally unsafe" or "marginally safe," according to the five-year safety report, which was compiled by U.S. and Mexican officials.

Despite the report's harsh language, officials said it is too early to raise red flags.

"There is no eminent danger and there is no need for anyone to be alarmed," said Sally Spener, spokeswoman for the IBWC. "What the inspectors are saying is that they need to take a closer look at those structures."

Amistad Dam, between Del Rio and Ciudad Acuсa, has raised more concerns and was classified as "urgent" and in need of further evaluation and study.

The commission noted that the classification is based on naturally occurring upstream sinkholes in the limestone foundation of the reservoir on which the Amistad Dam was built in 1969 for flood control and hydroelectric power.

According to the commission, Amistad Dam, which stands 254 feet above the riverbed and consists of a concrete spillway section flanked by earth embankments, is the largest of the storage dams and reservoirs built on the river between the United States and Mexico.

Kenneth Breiten, Amistad Dam project manager, said engineers have always been aware of the problem and fortified the foundation through the years, filling subterranean caverns with cement.

"The condition is not different than it was a year ago," Breiten said. "There is a difference in technology, and we expect to find and correct anything that was overlooked."

Joseph Coulter, president of the nonprofit Lower Rio Grande Water Committee, noted that if the Amistad Dam fails to contain water either because of the structural defects or a major hurricane, both the Anzalduas and Falcon would have to open their gates as well.

"Then all the water that is stored there would be dumped on the Lower Valley," Coulter added.

The IBWC found that all dams are capable of operating under normal and flood conditions, with the exception of Retamal Dam, near Donna, where the center gate is broken.

The dam's gate system broke under flood pressure in 2005, and engineers have made several unsuccessful attempts to fix the problem, according to the report. In the event of another flood, the center gate would have to remain fully closed as long as possible while the two side gates regulate the water flow released downstream.

IBWC's Spener said there is "no determination that dam cannot function" should a hurricane or flood hit the area. The commission is hoping to secure federal funding by next year to conduct more infrastructure analysis.

Hidalgo County spokeswoman Cari Lambrecht said the county has recently seen a lot of flooding, which did not affect the Retamal Dam's operations.

"But it's something to be concerned about," Lambrecht said. "It's not in our jurisdiction, and we hope that the IBCW takes it seriously and the federal government funds the study."

Coulter of the Lower Rio Grande Water Committee noted that the IBCW has a low priority when it comes to federal funding.

"They are probably somewhere on the Page 9 (of the budget) on the bottom," he said. "IBCW does not have enough constituency and it needs to be done on a grass-roots level."

austinova@express-news.net

[Hayduke]

Of course the dam that really matters to BBNP is the one on the Rio Conchos (in Mexico). I wonder how good that one is? (Not that I expect a hurricane to show up there anytime soon.)