Opequon Water Supply Plan (OWSP)

Frederick Water’s Opequon Water Supply Plan (OWSP) is an initiative designed to meet the growing infrastructure needs of Frederick County.  By 2035, our community may need as much as 12 million gallons of finished water each day, doubling today’s current demand!   The OWSP will prepare for the growing needs of our community through a series of interconnected construction projects:

Phase One:
                -Quarry raw water intake and pump station,
                -Henry F. Sliwinski Water Treatment Plant,
                -Pipelines to carry treated water to the existing distribution system.

Phase Two:
               -Opequon Creek raw water intake and pump station,
               -Raw water pipeline to the Henry F. Sliwinski Water Treatment Plant.

Future Opequon Creek Intake



Frederick Water initiated the Opequon Water Supply Plan (OWSP) program in late 2015 in recognition that the Frederick County community will continue to grow, and its water treatment facilities would not be sufficient for long-term needs.  While the original plan called for water to be treated from the Opequon Creek, an historic agreement with Carmeuse Lime & Stone in May 2020 allowed for the project to be reconceptualized.  Rather than the creek, the new Henry F. Sliwinski Water Treatment Plant will treat water pulled from a system of quarries in Clear Brook.  These quarries not only provide high-quality water, but also give Frederick Water access to nearly 3 billion gallons of water storage.  That’s enough to provide our community with water for a year!

The Opequon Creek isn’t forgotten.  In a future construction phase of the OWSP project, when customer demands for increased water warrant, the Opequon Creek will be utilized as an additional water source.

Construction Progress

Construction on the pipeline began in February 2021.  Construction on the Henry F. Sliwinski Treatment Plant began with a groundbreaking ceremony on March 2, 2021.  Watch the ceremony here!  Construction on the quarry intake is expected to begin in March 2021 as well.  All three portions of the project are expected to be complete by Spring 2023.  Check back periodically for project updates and construction photos! 

Henry F. Sliwinski and Executive Director Eric Lawrence break ground on the new water treatment plant.

April 8, 2021
Construction Progress April 8, 2021
May 17, 2021
Construction on the Henry F. Sliwinski Treatment Plant is well underway!  The underground piping is currently being installed, which will allow raw water to flow into the plant and clean drinking water to be delivered to the distribution system.
June 28, 2021

Tunnel excavation begins at the new intake site!  Once complete, this tunnel will allow us to pump millions of water each day from the quarry to the treatment plant.

July 23, 2021

The first structural concrete pour of the project, consisting of 110 cubic yards of concrete placed for the lowest elevation of the chemical rooms, is complete!

December 2021

Tunnel construction is complete!  

With all underground piping complete, the steel frame has been erected and masonry work begins.

February 2022

The East Pit Quarry is filling up, and the 10' tall tunnel is nearly submerged!

Walls have been added, and now the Henry F. Sliwinski Water Treatment Plant is getting a roof!


August 17, 2022: All three pumps at the new raw water intake were run for the first time. Water was pumped to the 100,000 gallon break tank at the Henry F. Sliwinski Water Treatment Plant before being returned to the quarry.

October 2022: The main structure of the Henry F. Sliwinski Water Treatment Plant is complete.  Inside, electrical work continues.


Learn more about the Henry F. Sliwinski Water Treatment Plant

The Henry F. Sliwinski Water Treatment plant will use state-of-the-art membrane technology to treat up to 8 million gallons of raw water per day!  Membrane treatment technology has a proven track record in Virginia and has been shown to remove 99.99% of giardia and viruses.  Raw water will be pumped through membrane filters to remove contaminants, then treated with chlorine to complete the disinfection process.  Next, our team of highly trained treatment operators will conduct quality tests to ensure the water meets or exceeds all health and safety standards.  Finally, the finished water will be pumped through the distribution system into homes and businesses throughout Frederick County!




Henry F. Sliwinski, for whom the plant is named, served as Frederick Water’s Treatment Superintendent for 43 years until his retirement in 2019.  His namesake plant will continue his legacy of providing clean, safe drinking water to the Frederick County community for generations to come.

Henry F. Sliwinski breaks ground on the water treatment plant that will bear his name.


Learn more about the water source

The Henry F. Sliwinski Water Treatment Plant, like all of Frederick Water's plants, relies on quarries as the primary water source.  The limestone in the quarries acts as a natural filter and provides high-quality water to our plants for treatment.  Our latest Water Quality Report is available here.
Because quarries are recharged through groundwater, it is important to protect groundwater in our community.  Read Frederick Water's Source Water Protection Plan here.  Learn how to do your part here.