UNDER THREAT
Freshwater mussels in Guadalupe River could go on endangered list because waters they live in have changed
By Elena Bruess STAFF WRITER
The Guadalupe River flows Oct. 11 near Center Point. The Guadalupe River Basin is home to three of six Texas freshwater mussels proposed for the endangered species list.
The Texas fatmucket is one of the six types of mussels being targeted.
The Guadalupe River flows near Waring in Kendall County. Mussels in the river that are proposed for the endangered species list are vital to the Hill Country’s ecology and food chain.
The U.S. Fish and Wildlife Service has proposed placing six Texas freshwater mussels on the endangered species list and designating nearly 2,000 miles of Texas rivers as critical habitat for them.
The Guadalupe River Basin — one of four river basins highlighted by the proposal — is home to three of the mussels: the Guadalupe fatmucket, the false spike and the Guadalupe orb.
As bottom feeders, freshwater mussels are vital to the Texas Hill Country’s ecology and food chain. Deep within the Guadalupe River, enveloped in mud and shielded from passing predators, they soak in muck and eat whatever bacteria, algae or other tiny organic particles come their way.
But now, these little mollusks are under threat.
In its proposed rule, the Fish and Wildlife Service said it determined that habitat loss through changes in water quality and quantity, as well as an increase in fine sediments, are the primary threats to the six mussel species. And because of drought, stagnant water and low river flow, the mussels could face extinction in coming years without adequate protection in Texas. As a result, water and river authorities must work with the Fish and Wildlife Service to consider how much water is being pumped from rivers and how much is going back in.
“One of the key impacts on these mussel species is river flow,” said Myron Hess, an environmental lawyer in Austin. “If the river stops flowing or dries up, the mussels are not going to survive. They’ll be more vulnerable to predators without the protection of water, and without a strong flow, pollution in the river could build up and adversely affect them.”
The public comment period for the proposed endangered species listing ends Oct. 25, and the listing is expected to be finalized next year.
Keeping a healthy flow
In Texas, state permits that authorize the withdrawal of water from publicly owned sources never expire. Until the early 2000s, such permits were issued based solely on people’s need for consumption, without regard for maintaining sufficient flow for a healthy ecosystem.
But in 2007, the Legislature passed a bill to protect ecological and economic resources that require healthy flow in rivers and streams. Since then, new water permits cannot be issued without ensuring that some water was reserved for downstream flow.
Nevertheless, Hess said not much has been accomplished since the bill was passed. No state-owned water has been set aside for flow protection, and initial flow standards were not as stringent as researchers and scientists believed necessary to protect Texas’ river ecosystems.
Meanwhile, without proper sediment controls, the development boom in South and Central Texas — including along the Guadalupe River Basin — can exacerbate erosion and sediment runoff into rivers, endangering the mussel habitat. Increases in the amount of impervious cover and water runoff can cause instability in river ecosystems.
The first water flow standards were adopted in 2011, and Hess said it’s time to reconsider the law, revise the standards and work with river and water authorities on conservation plans.
The proposal to put the mussels on the endangered species list might serve as a catalyst for such action, he said.
Designating a critical habitat, as the Fish and Wildlife Service proposes, would not necessarily restrict further development, the agency said. But it will require any federal agencies to consult with the Fish and Wildlife Service when they take actions that could adversely affect a mussel species or its habitat. This means that if a federal permit for new development construction could impact the Guadalupe fatmucket’s habitat in any way, the agency would have to speak with the Fish and Wildlife Service to make sure the development does not negatively influence the endangered mussels before going ahead with construction.
“We anticipate we’re going to have a good working relationship with these river authorities going forward,” said Matthew Johnson, the freshwater mussel conservation and recovery coordinator for the Fish and Wildlife Service.
Protecting the Guadalupe
By considering the mussel population today, river authorities can help municipalities avoid uncertainty about water later.
For the Guadalupe River Basin, the staff at the Guadalupe-Blanco River Authority has been thinking about it. The river is home to 18 federally listed endangered animals and eight federally listed threatened animals.
To address this, the GBRA is working with the Fish and Wildlife Service to develop a habitat conservation plan for the river. Nathan Pence, executive manager for environmental science at the GBRA, said the plan will take a few years to put in place, but he believes the authority will be prepared if the mussels are placed on the endangered list.
“The GBRA recognizes that freshwater mussels need quality of water and a quantity of water to survive and thrive,” Pence said. “But we also recognize that the people of Texas need that, too. We’re hoping this plan can provide the tools to accomplish both of these goals.”
The Fish and Wildlife Service is working with the Lower Colorado River Authority, Brazos River Authority and the Blanco River Authority on water flow conservation agreements.
The agreements can include additional research on freshwater mussels to better understand the threats to the species and develop a plan to mitigate them, Johnson said. Agreements can involve population monitoring, habitat monitoring and water modeling.
“We’re hoping to develop plans that will allow these authorities to maintain their operations and conduct their maintenance activities and make sure they’re meeting their needs going forward,” Johnson said, “but doing so in a way that can benefit freshwater mussels as well.”
Elena Bruess writes for the
Express-News through Report for America, a national service program that places journalists in local newsrooms.