Eenie Meenie Miney Mo, Which Dam First to Fix the Flow (The Story of 23 Dams)

Between 1959 and 1967, the Soil Conservation Service constructed 46 dams along Brushy Creek in Williamson and Milam Counties in Central Texas. The dams were rural farm ponds constructed for flood control and for reducing agricultural erosion. In 2001 the dams were assigned to two different managing entities. The 23 uppermost dams along Brushy Creek were placed in the hands of the Upper Brushy Creek Water Control and Improvement District (District). The remaining dams were placed in the care of the Lower Brushy Creek Water Control Improvement District. This paper deals only with the upper 23 dams.
When the dams were constructed, the population in Williamson County was approximately 35,000. Since that time, the population has grown more than tenfold to nearly 420,000 with subdivisions and critical public infrastructure constructed downstream of the dams, often within twenty feet of the downstream toe of the dam. As a result of the population growth and the extensive development around the dams, most of the dams were now classified as high-hazard structures. The high hazard classification required the dams to pass the probable maximum flood (PMF). A 2000 study found that the dams as designed, passed between 31 and 67 percent of the PMF. The study also found that over 1,100 homes were at risk due to potential dam breaches.
The District faced the challenge of determining the criticality associated with each dam and ranking them in an order for improvements. The ranking process evaluated hydraulic capacity and lives at risk. The program prioritized the order of construction and it was adjusted regularly based on new subdivision development. The District evaluated providing overtopping protection, increasing discharge capacity through enlarged emergency spillways, and increasing reservoir storage and discharge capacity through raised embankments.
To date, the District has invested nearly $22.5 million and has made significant progress towards completing the dam modernization program. A significant aspect of the program has been the District’s public outreach to the multiple jurisdictions within its boundaries.