To: Honorable Mayor and Members of Town Council
Through: David L. Corliss, Town Manager
From: Mark Marlowe, P.E., Director of Castle Rock Water
Matt Benak, P.E., Water Resources Manager
Title
Update: Appropriation of Conditional Water Storage Rights at Prewitt and Fremont Butte Reservoirs [Morgan, Washington and Logan Counties, Colorado]
Body
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Executive Summary
A key component of the Town’s long-term renewable water plan is to acquire additional renewable water rights to add to our water rights portfolio to help reach the eventual goal of becoming 100% reliant on renewable water in an average year. One of the projects identified in the 2016 Water Resources Strategic Master Plan included partnering with Parker Water and Sanitation District (PWSD) on a renewable water project in northeastern Colorado to divert, store and deliver water from that area back to Rueter-Hess Reservoir. This project is beginning to move forward and will also be included in the 2021 update to the Water Resources Strategic Master Plan. To lay Castle Rock’s claim to some of this water, we have filed an application with the Water Court to appropriate water under a 2021 water right out of the South Platte River at the Prewitt and Fremont Butte Reservoirs. This water right has the potential to yield up to 3,000 acre-feet of renewable water per year for the Town.
History of Past Town Council, Boards & Commissions, or Other Discussions
On October 27, 2021, Castle Rock Water Commission was updated on this item.
Discussion
The Town has had multiple discussions with Parker Water and Sanitation District (PWSD) over the past several years about partnering on their “South Platte Valley Water Partnership Project” (formerly known as the Logan Farms or Fort Morgan Project). Similarly, to PWSD, the Town has filed a Water Court application (Attachment A) for a conditional water storage right in Prewitt Reservoir via the Prewitt Inlet Canal and a conditional water storage right in Fremont Butte Reservoir (see location map, Attachment B). A delivery pipeline will be constructed from Prewitt Reservoir to Fremont Butte Reservoir, and water will also be able to be sent back to Prewitt Reservoir and pumped out into a long transmission pipeline all the way back to Rueter-Hess Reservoir. In partnership with PWSD, Castle Rock will be able to have this water treated and delivered to the Town’s service area for use by our customers. This new water right will also be able to be used to extinction meaning after using it we can pick it up at our various local surface diversions and storage reservoirs for reuse. Specifically, the Town is claiming a 111 cubic foot per second (cfs) flow rate from the South Platte River into the Prewitt Inlet Canal and 722 acre-feet (AF) storage right (with one annual refill of the same volume) into Prewitt Reservoir. This water can also be conveyed to and from the future Fremont Butte Reservoir. Additionally, the Town is claiming an 8,000 AF conditional storage right (with one annual refill of the same volume) at Fremont Butte Reservoir.
The South Platte Valley Water Partnership Project (Project) is a long-term renewable water project for both PWSD and Castle Rock and will likely involve other future partners. One early phase of the project may involve a pipeline from the Lost Creek area of Weld County where Castle Rock currently owns nearly 1,500 AF of water rights. This infrastructure would give the Town the opportunity to move this water to Rueter-Hess Reservoir in a timeframe of around 10 years. Construction of other major infrastructure associated with the Project will likely occur in the 2040 timeframe and beyond with conceptual project costs of approximately $400 million. Castle Rock’s share of this Project may be in the $80 million to $120 million range.
Budget Impact
Costs associated with development of the Water Court Application include both legal (Lyons-Gaddis) and engineering services (W.W. Wheeler and Associates). Funds have been drawn from 211-4340-443.30-50 Legal Services which has a remaining 2021 budget of -$4,638 and 211-4340-443.30-40 Engineering Services which has a remaining 2021 budget of $229,570. Legal and engineering work in support of this application is estimated to be up to $15,000. Water Resources staff will work with Finance to determine budget transfer details for the Legal Services account before the end of calendar year 2021.
Attachments
Attachment A: Water Court Application for Conditional Water Storage Rights (Draft)
Attachment B: Location Map of the South Platte Valley Water Partnership Project Infrastructure