Dam 101 is one of three projects identified as part of the Lake Creek Flood mitigation strategy to reduce the flood risk to life in property in the area designated as the worst damage center in both the WCID and Williamson County flood risk studies.
What does the new dam achieve?
Construction of Dam 101 will reduce flooding risks to over 380 residents and improve emergency access and response times during flooding events. Under the design models (USGS 2010 Rainfall) flooding reductions range from 6 feet within the most at risk areas of the Greater Round Rock West neighborhood to 1.5 feet at AW Grimes just before Lake Creek joins Brushy Creek.
Will this dam address all the flooding areas along Lake Creek?
No, while this dam addresses a large portion of the flooding risk in the Lake Creek Watershed all three projects are required to minimize the flood risk throughout the watershed. A proposed Dam 102 and a project addressing the flood storage needs in the 620 quarries are required to address existing Lake Creek flooding to the maximum extent practicable; however, neither of these projects would work properly without Dam 101 being in place. Dam 101 is the workhorse of the three projects. The future Dam 102 project is likely to be driven by development in a sub watershed of Rattan Creek. The 620 quarry project needs are being evaluated by the City of Round Rock.
Does this affect my Flood Insurance?
No, not yet. The CLOMR notice is FEMA’s acknowledgement that if the project is built according to the submitted plans then the included changes to the floodplain would be eligible for acceptance via submission of a LOMR (Letter of Map Revision).
What happens after a CLOMR?
- Once the dam is operational, the District will submit a LOMR to FEMA to amend the FEMA flood map to reflect the changes made by the new dam.
- The LOMR would make the modifications to the FIRM (flood insurance rate map) that insurance costs are based on.
Will there be new parks or trails associated with Dam 101?
No, the dam is being built on privately owned land. The District is only purchasing the land that will be under the footprint of the dam. The District is purchasing easements only to allow for the proper operation and maintenance of the dam. There will be no public access.
Permitting and Environmental
The District will go through all the applicable state and federal permitting processes and is working with the US Army Corps of Engineers (USACE), US Fish and Wildlife Service (USFWS), the Willamson County Conservation Foundation (WCCF), and others to ensure that environmental impacts are minimized during and after construction.
What is Atlas 14 Rainfall Data ?
In late September of 2018, the NOAA updated rainfall data for use in floodplain modeling in Texas. https://www.noaa.gov/media-release/noaa-updates-texas-rainfall-frequency-values In some cases, the data replaces data from over 40 years ago. In our area, the rainfall was updated with the recent FEMA floodmaps to leverage the 2010 USGS rainfall data. Dam 101 was designed with the latest rainfall data available at the time (USGS 2010 Rainfall) and was subsequently evaluated in 2019 after the release of Atlas 14. For more information please see the technical information page.