Water Master Plan

City of Lewiston, 
Idaho

Water Master Plan

Project Highlights: 
  • Conversion of the existing water distribution system computer model to an off-the-shelf software.
  • Updated population and water demand projections.
  • Recommendations for improvements to the water distribution, chemical feed, flash mix, and filtration facilities, as well as construction of a new 5-mgd water treatment plant.
  • Financial plan and funding recommendations.
Lewiston Aerial
Carollo’s water master plan for the City of Lewiston includes a CIP for projects required to meet current and proposed water quality regulations.

In 1997 the City of Lewiston selected Carollo to provide an update of its water system master plan. Lewiston plans to update the master plan every five years in order to keep a current capital improvements plan (CIP). The last master plan for the water system was prepared in 1991. The update provided by Carollo included a conversion of Lewiston’s existing water distribution system computer model to an off-the-shelf software (Haestad Methods' Cybernet®) in addition to updating the model to reflect changes in planning over the last five years.

Carollo also prepared updated population and water demand projections and prepared and scheduled recommendations for distribution system capital improvements projects in an updated CIP. The CIP also included projects required to meet current and proposed water quality regulations relating to Lewiston’s sources of supply.

Lewiston operates five wells, both for domestic and irrigation use, as well as a water treatment plant with a nominal capacity of 15 mgd. The source of supply for the treatment plant is the Clearwater River. An update of water quality regulations since the last master plan resulted in recommendations for the upgrading of chemical feed, flash mix, and filtration facilities. In addition, the construction of a new 5-mgd capacity base-flow water treatment plant is recommended, with completion by the year 2001.

The master plan also includes a financial plan with recommendations for funding the proposed CIP.

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