Boulder Reservoir Outlet Project

Boulder Reservoir Draining in Fall 2020 

The Boulder Reservoir outlet maintenance project is a joint effort between Northern Water and the City of Boulder. While the city owns the reservoir, Northern Water manages the operations and maintenance related to water storage and dam safety.  

Boulder Reservoir requires periodic sediment removal, structural inspection and repairs to maintain the safety of the dams and to ensure effective water delivery to downstream water users. Beginning Sept. 1, 2020, Northern Water will drain Boulder Reservoir to perform this routine maintenance.  

Why is this Boulder Reservoir maintenance project needed?  

This work is in response to the State Engineer’s inspection and recommendations made over the last several years, and is a follow-up to initial underwater observations and maintenance work performed at the outlet in fall 2018. The work is vital to the safety of the irrigation and drinking water supply and the infrastructure of the reservoir and dam.

What is the construction period?  

Draining of Boulder Reservoir will begin on Sept. 1, 2020, although reservoir storage levels may decrease before then due to demands on reservoir storage. Between September 2020 and March 2021, reservoir levels will be significantly lower than normal, and many recreation opportunities, including boating and small watercraft, will be unavailable during this time. Reservoir levels are expected to be back in normal ranges by April 2021. 

What does the project include?  
  • An assessment of the outlet trash racks
  • Inspection of the outlet pipe and gate
  • Removal of sediment around the outlet
  • Grade and install riprap along "Fisherman’s Point” between the north and south dam to mitigate erosion
How will this project affect the use of Boulder Reservoir for recreation?  

We realize that Boulder Reservoir has experienced a shortened recreational season due to COVID-19 and that this project will impact recreationists. However, doing the maintenance work when certain reservoir recreation opportunities, such as swimming, are already restricted due to COVID-19 will ensure that recreation can return to full service once the pandemic subsides. 

Who is paying for the project? 

The project will be paid for by Northern Water. 

Who do I contact if I have questions? 

If you have questions regarding the project or construction activities, call Northern Water at 800-369-7246.