San Marcos River dewatered, rerouted for portion of maintenance project

A portion of the San Marcos River near Rio Vista Falls has been dewatered and rerouted as a part of a City of San Marcos maintenance project.

Work began on the construction project in October and will address instream structures and bank improvements. Underwater voids and undercuts have formed in the bank and instream structures throughout the Rio Vista Falls area and require maintenance, the city previously said. 

Work is being done in coordination with federally permitted biologists in order to remove and relocate aquatic fauna including the endangered — federally/state listed — fountain darter where dewatering activities are taking place. Additionally, any federal and state protected Texas wild rice in the area will be removed, housed and replanted near its original location after construction is completed, according to the city. 

The contractor installed temporary pipe extensions to two existing 4-foot diameter pipes which are being used to divert river flow around the falls area. The existing pipes are located below ground along the east bank and begin at the dam area. The pipes end just upstream of the Cheatham Street Bridge. The pipe extensions will transfer and divert river flow discharge to the downstream side of the Cheatham Street bridge. Additionally, a rock gabion splash pad has been installed to protect against erosion.

The $970,000 project, which was awarded to Austin Filter Systems, Inc. The city previous said the project would take three to five months to complete with an expected completion date in March 2022.

Previous reporting by Nick Castillo included in this article.