Cedar Park is officially in on a major regional wastewater upgrade after City Council on Thursday approved an interlocal agreement to take part in designing a key piece of sewer infrastructure along Brushy Creek. The deal commits the city to help plan roughly 11,500 linear feet of interceptor that will run along the creek into Round Rock. City staff say Cedar Park’s share of the design cost will come from the city’s utility capital improvement program for the 2025–26 fiscal year, and they emphasize that this agreement covers design work only, with construction funding to be negotiated later.
As reported by Community Impact, the council’s vote on Thursday not only approved the interlocal agreement but also cleared staff to move ahead with the design phase. That reporting notes Cedar Park will draw its portion of the cost from the FY 2025–26 utility CIP and that the current pact is limited to engineering and design work at this stage.
How the cost will be split
Round Rock’s official council record spells out how the partners are expected to divide the bill: Round Rock 53.33%, Cedar Park 17.17%, Austin 15.79% and Leander 13.71%. The legislation says those percentages are based on projected wastewater flows in 2040 and identifies Walker Partners as the most qualified firm to handle engineering services. Round Rock staff will manage the project during the design phase, according to the same record. The full legislation text is available through Round Rock’s Legistar.
Design only, for now
The interlocal agreement is strictly limited to the design phase and does not lock any of the cities into paying construction costs under this contract. Cedar Park’s adopted FY 2026 budget includes a dedicated utility fund and a capital program that staff point to as the likely source for the design payment. Budget materials highlight a $45 million utility fund and outline ongoing capital investments in water and wastewater infrastructure, according to the City of Cedar Park.
Why this matters locally
The interceptor project is intended to add capacity and shore up a critical stretch of the Brushy Creek Regional Wastewater System that serves Austin, Cedar Park, Leander and Round Rock. According to the City of Round Rock, the regional system includes two treatment plants and about 45 miles of regional collection lines, and the city also manages more than 450 miles of local collection lines. Upgrades to the interceptor are designed to keep pace with fast population growth in the area and to cut down on the need for emergency repairs farther downstream.
What residents should expect
Design work usually involves capacity modeling, route analysis, environmental reviews and public permitting steps, and it can take many months to finish. Round Rock reporting notes that the city expects to bring additional items tied to the project back to its council as the design moves forward, then return with construction-level approvals for all the partner councils when plans are ready. Specific on-the-ground impacts, such as short-term excavation work or temporary lane and trail closures near the alignment, will not be locked in until the design is complete and construction plans are finalized.
Next steps
Walker Partners will now launch detailed engineering studies and produce design documents and cost estimates for the partner cities to review. Once the design phase is wrapped up, each city will be asked to consider construction approvals and corresponding budgets. The 2040-flow allocations that are built into the interlocal agreement will guide how the eventual construction costs are divided among the partners, according to Round Rock’s legislation records.
For the moment, the agreement simply secures local participation in the design phase and leaves the bigger construction decisions and price tag for another day, a setup city officials say is meant to keep the regional system ahead of growth without signing onto construction costs before the technical work is complete.
