Why Texas Water Planners Worry about Mussels

Texas Parks and Wildlife

Volunteers count mussels in Lake Arrowhead State Park in North Texas

You may have had mussels steamed in a bit of white wine and butter. But they most likely weren’t mussels from rivers or creeks in Texas.

“Their favorite food is bacteria. They are filter-feeders, the vacuum cleaners of the river systems,” said Marsha May, a biologist with the Texas Parks and Wildlife Department.

“They’re taking in all kinds of things that can be found in streams and rivers. And so they could be toxic,” cautioned May.

Not exactly appetizing. And maybe worse is what it says about the state of those Texas waterways.

“(Mussels) are an organism we consider a biological indicator of the health of the system,” said May.”Once the mussels start going, other organisms are going to follow.”

Some studies have indicated the population of native Texas freshwater mussels has been declining, so much that five species are now on a list of candidates for designation under the Federal Endangered Species Act.

Dave Fehling/StateImpact Texas

Non-native Asian clam shells are easy to find along the Brazos River. Harder to find are Texas mussels, below right

Under an agreement that came last year after a wildlife advocacy group, WildEarth Guardians, sued the Federal Department of Interior, the U.S. Fish and Wildlife Service is now gathering data to determine just how many mussels there are in Texas.

That is a worry for Texas water officials.

“If mussels get listed as endangered, it’s going to make it much more difficult to develop water supplies in Texas. It may make it more difficult to build reservoirs, for example,” said Robert Mace, Deputy Executive Administrator with the Texas Water Development Board.

The Texas fawnsfoot mussel, a candidate for the endangered species list

Efforts to protect endangered species can lead to costly lawsuits when wildlife advocates challenge the use of river water. Those advocates often argue that depleting the flow by diverting water to farms and cities upsets the delicate balance needed for river creatures to thrive.  The state and river authorities typically counter that the impact is minimal.

Bill West, the General Manager of the Guadalupe-Blanco River Authority in Seguin, said legal challenges could threaten the state’s ability to meet the demand for water.

“It has some major, potential impacts on the economic future of the State of Texas,” West said.

One such potential impact is 25 miles west of Houston. Near the town of Wallis in Austin County, the City of Houston has long-range plans to divert millions of gallons of water from the Brazos River into a reservoir it would build on some 9500 acres of what is now farm and ranch land. Two species of native mussels are known to inhabit this stretch of  the Brazos.

Dave Fehling/StateImpact Texas

Site for future reservoir in Austin County near Brazos River

“The identification of an endangered species in the area could have some effect on the building of the reservoir, ” wrote Judi Pierce with the Brazos River Authority in an email to StateImpact.

“Much depends on the type of species, where the species ranks on the endangered list, the location and the habitat of that species and how that species would be affected in that specific location by the building of the reservoir,” wrote Pierce.

In other words, a lot of ifs. Much will depend on the assessment by the U.S Fish and Wildlife Service. A decision could come in 2016 as to whether Texas mussels are so scarce as to warrant making them an endangered species.