Project Updates
On August 11, 2025, the Environmental Protection Agency (EPA) announced the Environmental Assessment and Preliminary Finding of No Significant Impact (FONSI) for the Columbia Power and Water Systems’ Long-Term Water Supply Program has been released for a 30-day public review. Dates and instructions for providing comment are included within the announcement on the EPA’s website.
Construction of the projects that are part of the Community H2O Long Term Water Supply Program (LWSP) will be completed in multiple phases and will continue throughout the next several years.
Existing Water Treatment Plant Improvements
The existing plant was originally constructed in 1952 and has been expanded and improved over the years. Work underway as part of the Community H2O Program includes:
Maintenance improvements at the existing Water Treatment Plant (WTP) to replace aging equipment throughout the plant, providing more reliable water treatment and greater operational flexibility.
Replacement of settling basin equipment, filter improvements and media replacement, disinfection system improvements, replacement of high service pumps and backwash pumps, replacement of the residuals pumps, chemical storage and dosing system improvements, miscellaneous yard piping and valve repairs, as well as electrical-power and controls improvements.
The next phase of improvements at the Existing WTP will include major raw water piping modifications, backwash recycling, and treatment and emergency power generation. These improvements are currently anticipated to start construction in early 2026.
Water Treatment Plant Expansion
Construction of a 12 million gallon per day (MGD) capacity expansion to the existing WTP will provide additional capacity for projected demands on the CPWS system. Once completed, the combined treatment capacity of the WTP will be 32 MGD between the existing conventional treatment plant and the new membrane treatment plant expansion. The expansion project will include new tank storage and high-service pumps to serve future peak demands, as well as provide operational flexibility for future maintenance activities. This project design is completed and anticipated to start construction in early 2026.
New “Downstream” Intake and Raw Water Pump Station
The Program includes expansion of CPWS’s water supply capabilities with a new raw water intake and pump station located downstream of Columbia on the Duck River on the far western edge of Maury County. The Downstream Intake will expand the total withdrawal capacity from 20 MGD to 32 MGD and will be the primary source of water from the river. The location of this new intake has been coordinated with local, state, and federal stakeholders and will not only provide additional raw water for CPWS’s customers but will also provide redundancy should drought or emergency conditions occur in the river. A new raw water pump station will be constructed at the downstream intake site to pump water back up to the WTP in Columbia. This project design is completed and anticipated to start construction in early 2026.
Raw Water Transmission Main
A large diameter raw water transmission main will be necessary to convey water from the new Downstream Intake to the expanded WTP in Columbia. This 36-inch diameter main will be constructed along the nearly 17-mile alignment through the west side of Maury County and then through the west side of the City of Columbia. Construction of the new main will include two trenchless river crossings and multiple highway and utility crossings. This project design is completed and is slated for construction starting early in 2026.