Dam 101 - A New Flood Mitigation Project

Dam 101 is one of the Lake Creek Flood Mitigation Projects (Dam 101, Dam 102, and 620 Quarry modifications) designed to substantially reduce flooding in the largest damage center in Williamson County. Collectively the Lake Creek Flood Mitigation projects reduce flooding to the maximum extent practicable; Dam 101 is the workhorse of the three projects and must be constructed first.

  • Dam 101 is a new Dam that will be nearly a mile long and four stories tall.
  • The dam will reduce flood risks for over 1,000 residents. 
  • The new dam reduces flood risks for approximately 5 miles of Lake Creek as it winds from the dam through the Greater Round Rock West neighborhood, past the IH 35 frontage roads and continues all the way down to just after Lake Creek Park.
  • The project also improves emergency access and response times to the area by reducing flood risk at multiple road crossings.
  • The anticipated schedule can be viewed below. Monthly updates can be found in the CIP Status Report.

Location Maps

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Floodplain Comparison Tool

Williamson County is  hosting a user-friendly mapping tool depicting the proposed changes in the 1% Annual Chance Event (aka 100-year) floodplain. The interactive map shows the changes between the current effective FEMA floodplain (used for flood insurance purchases) and the proposed changes modeled in the Conditional Letter of Map Revision (CLOMR).

Anticipated Schedule

Spring 2023                Estimated Start of Construction

Fall 2025                     Estimated Project Completion

Fall 2025                     LOMR (Letter of Map Revision) Filed with FEMA

Early 2026                  Anticipated approval of LOMR by FEMA  (Official floodplain map changes)