WESLACO — Historic floodwaters rushing through the Lower Rio Grande Valley as a result of Hurricane Alex bring both good and bad news for the area’s ecology, according to an official with the Texas Water Resources Institute.
Jaime Flores, the institute’s Arroyo Colorado watershed coordinator, said the almost incalculable amounts of water released from Falcon Dam on the Rio Grande will likely be a boon to the environment, but could also pose dangers to it.
The institute, located in College Station, is part of Texas AgriLife Research, Texas AgriLife Extension Service and the Texas A&M University College of Agriculture and Life Sciences.
“Consider first the amount of water we’re talking about,” he said. “For the better part of a month, Falcon Dam was releasing 60,000 cubic feet of water per second. My calculator won’t allow me to multiply that by 60 seconds in a minute, then by 60 minutes in an hour, times 24 hours in a day, times 30 days.”
To convert that to gallons, the number would have to be multiplied by the 7.48 gallons in a cubic foot.
“We’re talking several billion gallons of water per hour for several weeks,” he said. “Human suffering aside, that much water is going to affect the environment.”
This water is ushered out to the bay and Gulf of Mexico via a three-pronged system consisting of the Rio Grande, the North Floodway and the Arroyo Colorado, he said.
While lingering pollutants in the Arroyo and other waterways were likely flushed out to sea, others were brought in, Flores said.
“Those waters brought a lot of sewage and pollutants from both sides of the Rio Grande,” he said. “Hopefully, because of the volume of water involved, their toxicity was diluted,” he said.
Among the pollutants are fertilizers that could provoke red or brown tide algae blooms in the bay or gulf, Flores said, but added that he hoped these were adequately diluted so as not to provoke algae spores in the water.
Sea grasses, which serve as filters for the South Texas hyper-saline bay waters, are at risk because of their sensitivity to fresh water and changes in water salinity, he said.
“One part per million either way in the water’s salinity can affect the root systems and cause them to release and die,” he said. “This could be very dangerous, but we’re hoping the sea grasses reestablish themselves to maintain the healthy balance that gives the bay its clear, green color.”
Prolonged fresh water in the bay could begin to affect marine life, including oysters, fish and shrimp, Flores said.
On the positive side, the massive amounts of floodwater through the area’s waterways will likely reinvigorate wildlife habitat, he said.
“Native seed stocks will probably be replenished with the introduction of water-borne seeds from the mountains and deserts of Mexico, including yucca, cactus, palms and other plant species that were regularly carried to this area via floods before the construction of Falcon Dam in the mid-1950s.”
Fish populations should also benefit, Flores said.
“We’ll likely get what’s called hybrid vigor,” he said. “Various species of fish that had been locked behind Amistad and Falcon dams will breed with existing fish populations here, introducing new genetic material to the gene pool to hopefully create bigger and stronger fish.”
Flores is also hopeful that receding flood waters will leave behind enough water to fill and revive long dried and dormant ponds, resacas and wetlands in the levee flood systems.
“This historic flood caused a lot of human suffering, but the silver lining could be a revival in our waterways and wildlife habitat that will need our care and nurturing into the future,” he said.
Flores marvels that the area’s floodway system, parts of which were designed and built 80 years ago, worked as well as they did.
“While it’s not yet over, the best news is that we’ve managed to survive this historic flood without any loss of human life, Flores said.