Rehabilitation of an Existing Channel Dam Engineering and Environmental Issues Rio Vista Dam, San Marcos, Texas

A low dam on the San Marcos River downstream from Aquarena Springs, in Rio Vista Park, is popular for “river running” with tubes, kayaks, and canoes due to a slot near the middle of the structure. Late in 2005, kayakers noticed that existing cracks had expanded and reported the problem to city Parks and Recreation staff. A local engineer found the dam to be “in a state of relatively slow failure due to undermining of the foundation material under the downstream portion of the dam…in particular, a 50 foot long section of the concrete apron located on the right side of the dam had cracked in several places and had dropped approximately 12 inches.” The City then placed several signs to warn the public to keep away from the dam and informed the Texas Commission on Environmental Quality of the problem. The TCEQ inspected the dam and found that the concrete apron was separating from the body of the dam in fissures as large as a foot deep. The TCEQ subsequently issued a letter stating safety issues and public welfare concerns and the city began emergency repairs. 14 pp., 12 references.