Conroe, February 2 – Despite admonishment from the Texas Water Development Board, the rogue San Jacinto River Authority (TWDB) has ignored the need to conduct careful studies of the sedimentation rate in Lake Conroe. The admonishment came in a 2012 study with the enticing title, “Volumetric and Sedimentation Survey of LAKE CONROE June – August 2010 Survey.”
In TWDB’s engineering study of Lake Conroe, TWDB concluded that “Lake Conroe loses between 520 and 688 acre-feet per year of capacity due to sedimentation.” Sedimentation occurs from erosion of soils that reduce the water capacity of Lake Conroe, which is a man-made lake. Water flow carries the soils into the lake to reduce its capacity. (Wind swept erosion of soils can occur but is fairly insignificant.)
TWDB’s study found that, in 2010, Lake Conroe had a total reservoir capacity of 411,022 acre-feet and encompassed 19,640 acres at its conservation pool elevation (201.0 feet above mean sea level). In 1973, however, when SJRA constructed Lake Conroe, the lake had 430,260 acre-feet of reservoir capacity.
In the study, TWDB noted that sedimentation levels around the Lake Conroe Dam are higher than in other parts of Lake Conroe. Therefore, the state agency admonished SJRA, “TWDB recommends that a similar methodology be used to resurvey Lake Conroe in 10 years or after a major flood event.”
There have been three major flood events at Lake Conroe just in the past two years. In 2016, Montgomery County citizens suffered the Tax Day Flood and the Memorial Day Flood. In 2017, of course, Montgomery County citizens suffered Tropical Storm Harvey and SJRA’s decision to open its Lake Conroe floodgates essentially without warning to homes downstream which resulted in sweeping thousands of homes off of their foundations and destroying many thousands of others.
Amazingly, SJRA has failed to conduct sedimentation studies since the three major flood events.
These studies are particularly important, because Lake Conroe’s water storage capacity has likely declined dramatically since the 2016 Tax Day Flood. That decline could easily have impacted SJRA’s ability to prevent downstream flooding during both the 2016 Memorial Day Flood and 2017’s Tropical Storm Harvey disaster.
SJRA has had a statutory duty since 1937 “to provide flood control” and also “to prevent soil erosion.” Unfortunately, SJRA has focused on selling water at monopolistic prices rather than fulfilling its statutory duty to protect people who live in the watershed of the San Jacinto River (which such watershed includes all of Montgomery County) through flood control and flood mitigation.