Protecting the Tuolumne River with Modesto's River Trunk Pump Station Project

July 6, 2026, City Manager's Blog

If the Tuolumne Boulevard detours have caught your attention, there's a good reason. Modesto is investing in one of the most critical infrastructure projects in the city. The River Trunk Pump Station Project is the final phase of the Modesto River Trunk Gravity Realignment Project, which represents a major wastewater upgrade by the City of Modesto.

The goal of the entire realignment project is to

• Replace an aging sewer line.
• Reroute flows from the old River Trunk Pipeline into new sewer lines.
• Build a pump station to prevent spills, improve reliability, and address hydraulic issues.

The River Trunk Pump Station Project is fundamentally about protecting the Tuolumne River, one of Modesto's most vital natural resources. The Tuolumne River supports migratory birds, fish and wildlife, local plants, and even recreational activities such as fishing, boating, and picnicking. When aging sewer lines deteriorate or become exposed due to erosion, they can leak harmful bacteria into the river. Installing a new Trunk Pump Station will prevent that from happening thus protecting the environment and the surrounding homes and businesses in the event of flooding.

The project strengthens Modesto's wastewater system in ways that directly benefit residents and businesses. The new pump station and realigned sewer lines can reduce the risk of sewage backups, increase reliability, and improve the system's ability to handle heavy rainfall, translating to fewer disruptions and emergencies, and more reliable service for everyone.

As construction continues this essential infrastructure upgrade, the temporary closures along Tuolumne Boulevard and surrounding streets are necessary to keep the project on schedule and reduce long-term impacts. By fully closing a portion of Tuolumne Boulevard under the overpass, the City is able to shorten construction by 6-8 weeks and save an estimated one million dollars in construction costs that can be used to address other critical infrastructure projects.

Construction for this project began in January 2026 and will continue through late 2028. While schedules may shift as work progresses, updates to road closures and detours will be provided to help residents and businesses plan ahead. Your patience and cooperation make it possible for the City to complete a project that will strengthen wastewater reliability and protect our river, our homes, and our businesses.