Concerns over whether Colorado River inflows will be cut off from Matagorda Bay have been lowered thanks to substantial rains and runoff in September and October that provided some fresh water recharge to the Highland Lake reservoirs managed by the Lower Colorado River Authority (LCRA).

Last month the LCRA executive board approved submission of an emergency request to temporarily cut river inflows to the environmentally fragile Matagorda Bay system in an effort to meet the growing water demands of its many city, industry and agriculture customers.

The action was opposed by some environmental, conservation and wildlife groups, including Ducks Unlimited, who argued such action would provide potential negative impact to wildlife and the environment in an around the bay.

Appearing before the group in September, Ducks Unlimited Conservation Outreach Biologist Kirby Brown told LCRA board members that water conservation measures currently in place are not adequate and said that current LCRA water conservation programs penalize agriculture and the environment while allowing other water users to continue using water irresponsibly.

 

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To better serve all interests, Kirby suggested a shared responsibility for water conservation, criticizing urban homeowners for unnecessary use of water to green their lawns and wash their cars while farmers were forced to cut food production and wildlife and the environment in general were suffering the consequences of not enough water to go around.

But even as the September meetings were taking place, rains began falling across much of Texas and continued into the early days of October. But before the heavy rains subsided, LCRA had approved and sent the emergency request to the Texas Commission on Environmental Quality (TCEQ).

But on Oct. 16, LCRA sent out another request to the state water control agency asking it to delay consideration of the issue until Nov. 27, at the earliest. That’s because recent rainstorms generated enough flow in the river to meets the bay’s freshwater needs in October.

LCRA’s state-approved Water Management Plan requires Highland Lakes water be sent under certain conditions for the environmental health of the bay. LCRA released 8,684 acre-feet from lakes Travis and Buchanan in September to meet some of the requirements from earlier in the year. After the water arrived, salinity levels in the Bay’s delta dropped from 33 parts per thousand (ppt) to less than 28 ppt. Scientific studies have determined that levels greater than 30 ppt may not be suitable for oysters, juvenile fish and other species in the bay. Additional freshwater flowing into the bay from rain in September and October is expected to help maintain lower salinity levels.

Rains improve oxygen content

LCRA analysts say the higher flows caused by the release and recent rains also scoured some of the aquatic vegetation from the lower Colorado River and raised dissolved oxygen levels in the river’s water, which should benefit fish and other aquatic life.

LCRA could be required to release up to an additional 5,834 acre-feet by the end of the year unless the Texas Commission on Environmental Quality (TCEQ) grants LCRA’s request to waive the requirement.

The river authority asked for relief because Central Texas is experiencing one of the worst droughts in history and lakes Travis and Buchanan were nearing all-time lows. September and early October rains helped by adding roughly 22,000 acre-feet to the lakes, but LCRA says the combined storage of the lakes was still only 33 percent of capacity and suggested it would take more than 1.3 million acre-feet to fill the lakes to capacity.

Since the delay request was sent, lake levels have increased slightly. As of Oct. 28, Lake Buchanan levels were up to 37 percent capacity and Lake Travis levels were up to 34 percent capacity. The combined storage capacity for both lakes has risen to 35 percent capacity.

LCRA says the two lakes provide water for more than a million central Texans as well as businesses, industries and the environment throughout the lower Colorado River basin. But the Authority warns that only rainfall and inflows produced by that rainfall can fill the lakes, and much more rain is needed.

Lakes Travis and Buchanan provide water for more than one million Central Texans and industries, businesses, agriculture and the environment throughout the lower Colorado River basin. LCRA says they made the initial request to waive the environmental requirements for 120 days or until enough rain falls to increase the combined storage of lakes Travis and Buchanan to 900,000 acre-feet (about 45 percent of capacity). If more rain is not forthcoming in November, they say they will proceed with the request.

The Matagorda Bay system is the second largest estuary on the Texas Gulf Coast. It provides an excellent nursery and feeding area for many species of fish, shrimp, shellfish and other marine life. Because of the serious, prolonged drought, the amount of freshwater flowing into the bay is at historically low levels, and the salinity level, or salt content, is higher than is generally considered suitable for many of the juvenile marine organisms that use the estuary to grow and develop.

 

More from Southwest Farm Press:

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