Contact: Lisa Sigler
303-778-8355 O
303-916-2257 M

Collaborative South Platte Basin Study Concludes Concept Could Help Meet Projected Water Supply Gap

March 10, 2020 – Denver, CO – A South Platte Regional Opportunities Water Group (SPROWG) study has evaluated several innovative regional water supply options that could help fill the greatest supply gap projected for any of Colorado’s river basins. The study evaluated four viable concept alternatives that would use a combination of off-channel water storage at multiple locations, infrastructure and water exchanges to develop additional water supplies from the South Platte River. The concept could meet future water needs of cities and agricultural water users within the basin and potentially enhance the environment and provide recreational opportunities.

The South Platte River Basin’s population, which includes the Denver Metropolitan area and rapidly growing communities north of Denver, is projected to grow from 3.8 million to 6 million people by 2050.

Updates to the Colorado Water Plan project a municipal and industrial water supply gap in the basin of between 185,000 to 540,000 acre-feet annually by 2050 based on varying supply and demand projections.

Concerns about the projected gap, and strategies to address it, were the focus of the 2015 South Platte Basin Implementation Plan, which included the original version of the water supply concept examined in the SPROWG study. The South Platte Storage Study, which focused on strategies for developing future water storage, estimated that almost 300,000 acre-feet of South Platte water is leaving Colorado annually in excess of the amount needed to satisfy compact requirements with the state of Nebraska.

“While communities in the South Platte River basin continue to make great progress in decreasing water demands through conservation and reuse, and are actively pursuing projects and strategies to meet our future demands, there remains a need for additional supplies,” said Lisa Darling, Executive Director, of the South Metro Water Supply Authority and advisory committee member.

For the past year, a contractor team led by a 14-member advisory committee comprised of South Platte and Metro Basin Roundtable members and other interested stakeholders evaluated four conceptual alternatives that could yield at least 50,000 acre-feet of water for municipal and industrial purposes and 10,000 acre-feet for agriculture. In addition, strategies for enhancing the environment and providing recreational opportunities were assessed in collaboration with stakeholder groups. Each of the alternatives would store and conjunctively manage water that would be drawn from available flows in the South Platte River not obligated to existing water rights, reusable water that has been treated and returned to the river, and temporary leasing arrangements with farmers sometimes referred to as “alternative water transfers” or “water sharing agreements”. The alternatives seek to efficiently use these sources of in-basin supply without relying on past practices of diverting additional water from the Western Slope or permanently drying up agricultural lands in the South Platte basin.

A significant portion of the water would be targeted for smaller rapidly growing communities along the I-25 and Highway 85 corridor between Denver and Greeley. Other communities in northern Colorado and the metro Denver area could also utilize the supplies.

The four water supply alternatives evaluated include multiple, operationally linked storage facilities (above and/or below ground) capable of holding between 215,000 and 409,000 acre-feet of water at various locations between Denver and the Colorado Nebraska state line. The water would be transported via a pipeline or through “exchanges” or trading water from one location to another.

The SPROWG study, funded in large part by a grant from the Colorado Water Conservation Board, built upon the work of others who had analyzed various strategies that would develop several types of South Platte water supplies to meet multiple benefits. Following are the alternatives studied:

“The amount of stakeholder input throughout the study process is unprecedented for a water concept in Colorado,” said Joe Frank, General Manager of the Lower South Platte Water Conservancy District, who oversaw administration of the grant. In addition to the advisory committee, the study team received input from a 90+ member task force open to any interested stakeholder. Broad public input was sought through multiple surveys and meetings with municipal and industrial interests, agriculture and environmental and recreational stakeholders. For example, stakeholders voiced that a SPROWG concept should not convey or manage supplies from “buy and dry” activities and noted that water from a SPROWG concept, as well as other sources, should be used as efficiently as possible. Stakeholders resoundingly said that the SPROWG concept should meet the goals of Colorado’s Water Plan and the South Platte Basin Implementation Plan, be operated in compliance with Colorado water law and the South Platte River Compact and fit within the Platte River Recovery Implementation Program.

Also studied were potential organizational structures to manage and potentially facilitate funding for the SPROWG concept. The top options included a new water conservancy district, a private non-profit company, regional water authority, or interim mechanisms such as an intergovernmental agreement or memorandum of understanding.

The conceptual cost estimates for the concepts ranged from $18,400 to $22,800 per acre-foot for raw water and $33,600 to $43,200 per acre-foot for treated water, which are in line with other large regional water projects. These costs included the anticipated water treatment strategies that were evaluated to make the water suitable for potable uses. While the most expensive to build, Alternative 4 had the lowest per acre foot cost of the alternatives because it has the highest yield. To move the study ahead, it was suggested that the SPROWG concept be included in the upcoming update of the South Platte Basin Implementation Plan.

“The goal was not to identify a favorite concept, but rather explore a range of options that may be feasible for cities and agricultural interests to evaluate as a collaborative project,” said Frank. “The next steps are to engage the actual concept proponents who may be interested in carrying the conversation further and continue to refine the concept to best meet their needs.”

To view the study:

Submitted to The BARN by:

Casey Davenhill
Executive Director
Colorado Watershed Assembly
(303) 345-1675


By Brian Allmer - The BARN

Brian Allmer & the BARN are members of the National Association of Farm Broadcasting (NAFB), the Colorado FFA Foundation, the Colorado 4H Foundation, the Colorado Farm Show Marketing Committee, 1867 Club Board Member, Denver Ag & Livestock Club Member, the Weld County Fair Board, the Briggsdale FFA Advisory Council, Briggsdale 4H Club Beef Leader & Founder / Coordinator of the Briggsdale Classic Open Jackpot Show.