Lake Somerville’s BRA-funded Aquatic vegetation program is a joint success

Aquatic plants may seem like a nuisance to some, but without them, a reservoir’s water quality and its fish can suffer. Why? Shoreline aquatic plants can improve water quality and clarity, they can stabilize sediment and even protect shorelines from erosion. They also serve as shade during the hot summer months and provide a place to live for the many types of fish that make the reservoir their home.

Somerville Lake, a U.S. Army Corps of Engineers reservoir and part of the BRA water supply system, is located on Yegua Creek in Burleson, Lee, and Washington Counties. The reservoir was one of several lakes within the Brazos River Basin identified by the Texas Parks and Wildlife Department as having suffered large losses in fish populations due to a loss of habitat during extended drought conditions a decade ago. As a result, a 2014 Memorandum of Understanding between the BRA and the Texas Parks and Wildlife Department allowed for placement of manufactured fish habitat structures, coined fish condos, in the deepest areas of these reservoirs to help preserve and increase fish populations when lake levels declined.

Since the program began, Somerville Lake has experienced an additional problem. Following the extended drought, the reservoir experienced periods of high water levels that resulted in water being stored in the lakes’ flood pool for extended periods of time.

A recent survey by TPWD found that some 80% of the reservoir’s shoreline had become bare and unvegetated, with less than one acre of live submersed aquatic vegetation available for fish to live and spawn.

Aquatic cover, such as coontail, a brushy type of underwater grass, also provides fish habitats that support the many different types of sportfish that make Somerville Lake their home, including Largemouth and White Bass, crappie, Channel and Blue Catfish and Hybrid Striped Bass. Adding aquatic plant life to the reservoir became a secondary effort to improve fish populations.

TPWD began growing aquatic plants in outside vegetation boxes at their College Station field office and constructed 15 floating cages that would be placed on Somerville Lake to provide cover for the sportfish population. In June 2023, the cages were filled with plants large enough to remain within the cages and later come to seed.

But the process was inadequate due to a limited outdoor growing season. To accelerate the process, the TPWD Inland Fisheries Division developed a plan to build a greenhouse equipped with three 300-gallon poly water tanks to grow coontail and other aquatic vegetation year-round. With funding from the BRA, in July 2024, TPWD built a 10 x 20 aluminum framed greenhouse to raise their own aquatic vegetation throughout the winter months, allowing earlier transplanting into the reservoir cages.

According to Dylan Kwak, TPWD fisheries biologist, the program is off to a great start. “The plants are doing good and the greenhouse is maintaining warm temperatures,” Kwak said.

“We expect the current plants to be ready to be added to the floating aquatic vegetation in the springtime,” he added. “We will wait until water temperatures are optimal for growing conditions within Somerville Lake before adding the plants - which should be in late March. We will then add mature plants to the cages, which will be ready to spread by fragmentation at the time of introduction.”

The greenhouse project will benefit primarily Somerville Lake and other district water bodies for years to come. TPWD will continue to monitor the efforts of the aquatic vegetation cages and map any growth or expansion of aquatic vegetation.