Siena Reservoir Pump Station and Pipeline

The Siena Reservoir Pump Station and Pipeline Project includes a new pump station and pipeline to convey water from Siena Reservoir to Broomfield's water treatment plant in order to assist in meeting water demands during peak summer months. Preliminary site preparation work is scheduled to begin February 28, 2023 which includes initial tree mitigation work and trail enhancements in the area for the needed trail detour. Full construction is anticipated to begin June 1, 2023

The first step to constructing the intake structure and other key facilities included in the project will be to drain the reservoir completely. Staff intends to make these releases as soon and as slowly as possible to ensure the safety of the dam and also to avoid any negative downstream impacts. Releases from the reservoir are expected to begin during the first week of March. It will take roughly 2 months to drain the reservoir completely, followed by a 18-24 month construction window depending on weather and equipment procurement. It is anticipated the reservoir will be refilled during the summer of 2024. 

If you have any questions about the project please contact Broomfield’s CIP Project Manager Ronda Jo Ackerman Alford at


Moltz Construction was selected in early 2022 as the Construction Manager/General Contractor (CM/GC).  The CM/GC will assist with reviewing constructability, analyzing potential cost savings and scheduling of the project.  Council approved an early work package (EWP) with Moltz at the December 13, 2022 council meeting.  The work includes procurement of long lead items (pumps and controllers), tree mitigation and trail improvements to allow for trail detours.  The early work on-site is expected to begin March 1.

Since the size of the pump station building will exceed ten percent from the original Site Development Plan (SDP), the project will require a SDP amendment. The team has been progressing through the process which has included a neighborhood meeting held on Wednesday, May 4, 2022 and several formal submittals to Planning.  The team submitted a third package in January 2023 and is waiting on the finalization from Planning. 

The Siena Reservoir Pump Station and pipeline project is to construct a station and pipeline to pump and transfer raw water from Siena Reservoir to Glaser Reservoir and the Water Treatment Facility to assist in meeting the water demands for Broomfield residents. Council approved a design consulting agreement with Muller Engineering for design and construction documents on May 11, 2021.

The City and County of Broomfield (Broomfield) at the November 10, 2020 Council Meeting retained Muller Engineering Company to complete a Preliminary Design Report for the design of a pump station and associated pipeline from Siena Reservoir (Siena) to the Broomfield Water Treatment Facility (WTF). Siena is located northeast of the intersection of Lowell Boulevard and Sheridan Parkway and south of the Northwest Parkway in Broomfield with a normal storage capacity of 450 acre-feet.  The WTF is located at 4395 west 144th Avenue, Broomfield, Colorado.  

A pumping station at Siena and a pipeline will deliver water to the WTF.  The facilities would assist in meeting peak summer demands for potable water.  The anticipated capacity of the facility would be 10 to 15 cubic feet per second (CFS) and 14,200 feet of pipeline expected to be 20 to 30 inches in diameter.

Broomfield has two major water supply sources: treated water purchased from Denver Water, and raw water from both the Colorado-Big Thompson (C-BT) and Windy Gap Projects. One of the City Council’s ongoing priorities is water resource acquisition and development. This includes efforts to continue moving the Windy Gap Firming Project (WGFP) forward, acquiring water rights, and constructing new capital facilities. 

Broomfield’s Water Treatment Facility (WTF), located at 4395 West 144th Avenue, treats the raw water supplies from the C-BT and Windy Gap Projects. A CIP project to expand the WTF by 6 MGD to its current 26 MGD was completed fall 2020.  

To provide a sufficient water supply to the Water Treatment Plant (WTP) during summer when water demands are highest, additional raw water storage is needed in Broomfield. Siena Reservoir is an asset of the Water Fund and is filled by a connection to the Carter Lake pipeline. Stored water cannot be drained except through the spillway and a new pump station and pipeline is required to deliver the water from Siena Reservoir to Glasser Reservoir or directly to the WTP. The improvements will provide seasonal summer storage for the next 10 to 15 years years until the Broomfield Reservoir is needed. A map showing the location of Siena Reservoir and proposed pipeline alignment is shown here:

Siena Oct. 2022

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Siena Fence Oct. 2022

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