In November, the District will ask voters to consider an $85 million bond program to fund flood safety projects throughout the Upper Brushy Creek watershed.
As with any large capital improvement program, issuing bonds would enable the District to address flood safety projects faster than saving tax revenue over time to construct projects on a pay as you go basis.
If approved by the voters, the bond would fund flood safety projects that were identified in the District's 2016 Flood Protection Plan and 2020 Dam Assessment Study. Projects are described in general below and more fully in the Engineering Report
The proposed bond projects fall into two categories:
Flood Mitigation and Dam Rehabilitation
Flood Mitigation Projects
The 2016 Flood Protection Plan was based on a “study to quantify relative flood risk level within the watershed” … “to identify existing creek flooding concerns, prioritize those concerns, and propose potential alternatives for the mitigation of the highest priority concerns”. Projects that would be funded by the bond will mitigate flooding in two of the most at-risk areas in the County. These projects will also protect infrastructure and improve emergency access to the area by reducing flood risk at multiple road crossings.
Block House Creek The proposed multi-phase project, in partnership with the City of Cedar Park, plans for channel and other drainage improvements.
Lake Creek The proposed multi-phase project, in partnership with the City of Round Rock, includes the construction of a new dam - Dam 101. As bond capacity allows , the District will work with communities to address regional flood mitigation risks identified in other areas.
Dam Rehabilitation Projects
Like all aging infrastructure, dams require rehabilitation to keep them working safely and effectively. The 2020 Dam Assessment Study categorized breach risk using the Joint Federal Risk Category method – an approach developed by multiple federal dam agencies for use in portfolio risk management (FEMA 2015). The Study prioritized rehabilitation projects to evaluate and implement the most cost-effective ways to alleviate current issues and protect against future ones.
As earthen dams age, their steep, sloping sides can become unstable as their soil settles or as animals or people compromise the soil, vegetation, etc. The Dam Assessment Study found that approximately 25% of the risk of the District’s portfolio is associated with the embankments and parapet walls.
Water typically leaves a dam’s reservoir through its principal spillway. The spillway’s many elements can deteriorate over time and require reinforcement or replacement. The Dam Assessment Study found that only a small percentage of the District’s portfolio had principal spillway issues. In addition, to remediate existing issues the District will look to optimize the spillway capacity.
Auxiliary spillways perform the critical unction of safely passing floodwaters without compromising the dam’s integrity. Erosion on an auxiliary spillway can result in damage and potential dam failure. The Dam Assessment Study found that more than 60% of the risk of the District’s portfolio is associated with the auxiliary spillways. Rehabilitation projects will strengthen the spillways and protect against future issues.
WHERE DID THE PROJECTS COME FROM?
Collaborative Community Driven Process
The District worked hand-in-hand with local governments and the public to develop the Flood Protection Plan that identified the areas of greatest flood risk and potential solutions.
Prioritized Mitigation Solutions
Since the Flood Protection Plan, the District and the communities have continued to collaborate to develop solutions for the two greatest risk areas of Lake Creek and Block House Creek.
Focused Rehabilitation Solutions
The Dam Assessment Study identified and prioritized dam rehabilitation projects with thorough analysis and technical input from industry experts, regulators, and District staff.
Since 2001, the District has been budgeting the maximum voter-approved two-cent tax rate to slowly save funds for costly flood safety projects. While this system has allowed the District to implement projects over time, it takes years of saving to fund smaller rehabilitation projects and delays more costly projects.
Bond funding allows the District to complete projects more quickly —
In the same way that a mortgage allows homeowners to buy a home and pay over time, using bonds allows the District to fund flood safety projects now, paying off the debt with future tax revenue.