Flower Creek Dam

Flower Creek Dam

Award Winner: 2013 Engineering Excellence Award from the American Council of Engineering Companies of Montana, Studies, Research, and Consulting Category

Residents of Libby, Montana, have relied on the Upper Flower Creek Reservoir impounded by 55-foot high Flower Creek Dam for high-quality drinking water since 1946.  The dam has been operated by the City of Libby and impounds the raw water above the water treatment plant. An inspection in 2009 and a subsequent material analysis in 2010 identified a serious deficiency in the concrete that estimated the safe operating life of the dam to be five years or less. The City of Libby immediately began considering options to maintain a safe and reliable water supply for the community. Morrison-Maierle prepared several studies and reports for the City of Libby, culminating in the 2011 Dam Replacement Alternative Report and the 2012 Water System Preliminary Engineering Report.  Through this process Morrison-Maierle developed four replacement dam alternatives and evaluated them against a wide range of feasibility measures including initial costs, long-term operational and maintenance costs, service life, and complexity of construction. Based on these analyses, the replacement of the Flower Creek Dam became the most cost-effective solution for the City of Libby’s water supply needs.

The replacement Flower Creek Dam is located adjacent to the site of the existing structure, which will be partially demolished.  The new reservoir will provide 220 acre-feet of storage for the municipal water supply. In addition to designing and permitting the new dam, Morrison-Maierle staff have also designed and permitted the temporary stream by-pass and a temporary chemical feed system linked by SCADA to the existing water treatment facility. We have also worked closely with the City to complete the threatened and endangered species biological assessments, wetland and riparian assessments, bidding and construction management. This project has also required citizen involvement in the form of multiple public meetings. Morrison-Maierle and City of Libby staff have coordinated the permitting work with various local, state and federal regulatory agencies.

Water rights have also been updated to include a storage water right. The volume of the current water right was increased to account for existing and potential growth within the water system service area. This updated water right is projected to provide drinking water for the community through the year 2040.

Construction of the dam began late fall of 2014 and is now completed.

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