WESLACO — The IBWC has issued a varied account on the safety of four key dams on the Rio Grande with designations ranging from the “marginally safe” to “potentially unsafe” found in a report from technical advisers from the IBWC.
The report emphasizes the overall structural safety of the dams located along the Rio Grande namely Amistad, located upstream from Del Rio; Falcon, located 80 miles south of Laredo; Anzalduas, located in Hidalgo; and Retamal, located near Donna.
Additional research is required to determine exactly whether or not there are issues with the safety of all the dams on the Rio Grande, according to IBWC engineers.
The Army Corps of Engineers assesses its dams by placing them into Dam Safety Action Classes (DSACs) from I being the most urgent to V (minimal) weighing on individual dam safety risk and the probability of failure and resulting failure consequences.
“What they are saying is, based on the results of their assessments is that if there was a problem with the dam that resulted in failure, the level of the amount of damage to the community, coupled with the things that are wrong with the dam, is how they arrive to that conclusion,” said IBWC principal engineer Al Reira.
“We monitor how much water is coming out of the other side of the dam. That is something we have done for the past 10 years, and even after than we have continued with the same parameters monitoring and we have seen a significant change on those, even if we do have a lot more water on the dam,” he said.
Amistad, the largest of all storage dams and reservoirs, has been given a DSAC II, or urgent classification, designating the structure as “potentially unsafe.” Urgent action is needed because there is high risk for potential loss of life and economic damage, according to the IBWC.
Falcon Dam is located about 150 miles above the mouth of the Rio Grande has been designated DSAC III, high priority, meaning the dam is “conditionally unsafe” due to a history of seepage. The IBWC report says the project has a very high population and infrastructure at risk in the U.S. and Mexico.
Retamal Dam near Donna has also been classified DSAC III due to a faulty central gate.
Anzalduas has been designated DSAC IV, meaning the dam is “marginally safe” with recommendation by the Army Corps of Engineers to update its electrical and mechanical systems.
Following an ongoing five year inspection to address the conditions of the dams, experts do not have enough information to ascertain whether or not a problem exists, according to the IBWC.
IBWC officials are cautiously taking a wait and see approach on the status of the key flood control structures on the Rio Grande.
The Lower Rio Grande Flood Control Project involves Anzalduas and Retamal diversion dams exclusively. The project covers 180 miles of the Rio Grande from Penitas, Texas to the Gulf of Mexico.
Anzalduas is used to divert the U.S. floodwaters into the U.S. interior floodway, to divert water into Mexico’s main irrigation canal, and to release water downstream for users in both countries. Retamal Dam is used to divert Mexico’s share of floodwaters into Mexico’s interior floodway and to regulate flood flows downstream.
“The monitoring by IBWC in this situation has been stepped up by the way. We are encouraged that once the priorities have been identified on how to address this situation we can work with IBWC to secure the resources to do what needs to be done,” Jones said. “This involves the Mexican investment as well, and participation with the issues on the Mexico side.”