Integrated and Sustainable Water Management Plan for a Growing City - A Case Study (Part 1)
Rueter-Hess Reservoir - future capacity
This three-part blog series is derived from an accepted paper that was published as part of the proceedings of the 2020 World Environmental and Water Resources Congress, originally scheduled for May 17-21 in Henderson, Nevada, sponsored by the Environmental and Water Resources Institute (EWRI) of the American Society of Civil Engineers (ASCE). The event was cancelled due to the COVID-19 pandemic.
INTRODUCTION
The vast majority of the available water supplies in Colorado are still associated with irrigated agriculture even while the state’s population is growing at a very fast rate and creating an ever-increasing demand for municipal water supplies. Since irrigated agriculture represents a significant part of the state’s economy it is unwise to remove irrigation water from agricultural uses to serve growing municipal demands, i.e., the concept of “buy and dry” of irrigated lands. The Parker Water and Sanitation District (PWSD), a quasi-municipal water provider, and the Lower South Platte Water Conservancy District (LSPWCD), serving a principally-agricultural area, have joined forces to develop a very innovative means to sustain historic agricultural irrigation practices while, at the same time, providing much-needed municipal water supplies to assure a sustainable water supply for the future of PWSD’s customers, as well as potentially other municipal water suppliers along Colorado’s Front Range. This water development plan may become the template for future water supply development to meet the needs of both major economic sectors in Colorado.
BACKGROUND
Parker, Colorado is a growing city in the Denver metropolitan area; with a current population of approximately 60,000, it is expected to grow to approximately 150,000 by 2040. PWSD, which provides water service in Parker, is currently mostly reliant on non-renewable groundwater resources from deep bedrock aquifers beneath the district. Given the tenuous long-term viability of non-renewable groundwater resources that are experiencing water level declines, PWSD took the first step towards reducing its dependence on these non-renewable groundwater resources by recently permitting the 72,000-acre-foot (ac-ft) Rueter-Hess Reservoir adjacent to the district. Construction of the dam was completed in 2012 and the reservoir is currently filling. However, the current sources of water for Rueter-Hess Reservoir are not sufficient to serve PWSD’s ultimate service area without an ongoing dependence on non-renewable groundwater sources. The district’s service area and the location of Rueter-Hess Reservoir are shown in Figure 1.
To meet its future water needs, PWSD has developed a strategic long-term water supply plan to provide renewable water supplies for a sustainable municipal supply into the future. The tremendous growth in Colorado, and the limited available water supplies, has required PWSD to develop an innovative plan to be able to meet its future demands with a sustainable water supply that is both renewable and reliable. As part of its strategic plan, PWSD wants to develop its renewable water supply plan without causing injury to other vital segments of Colorado’s economy.
Figure 1: PWSD Service Area
Figure 2: LSPWCD-PWSD service area boundaries.
Even with the large population growth in urban areas in Colorado, currently almost 90 percent of the available water supplies are still being utilized in agricultural irrigation and these supplies represent the most senior renewable water rights in the state. Agriculture is a major part of Colorado’s economy, generating over $6.2 billion of revenues and it has always been a hallmark of Colorado’s history. However, the demand for ever-increasing municipal demands, e.g., Colorado has grown in population from 4.14 million in 2000 to 5.70 million in 2019 (an increase of 38%), has put a severe strain on already limited water supplies. In addition, the 2015 Colorado Water Plan (2015 Plan) prepared by the Colorado Water Conservation Board (CWCB) projects population will increase to 8.6 to 10.0 million people by 2050. Related to this projected growth, the 2015 Plan projects there could be a statewide water supply shortfall by as much as 560,000 ac-ft/yr.
NOTE: Effective, January 2023, the 2015 Colorado Water Plan has been replaced by the 2023 Colorado Water Plan.
Historically, a number of conversions of agricultural water to municipal use were accomplished through a “buy and dry” situation, where agricultural water rights were taken from the land and moved to serve municipal interests, thereby drying up the productive farmland, potentially creating erosion issues on the fallowed land, and negatively impacting rural economies. The 2015 Plan seeks ways to avoid “buy and dry” scenarios. This requires innovative thinking to develop win-win scenarios when agricultural and municipal interests are vying for the same water.
PWSD has created such an innovative scenario by using its agricultural interests on farms in eastern Colorado (“Logan County Farms”) and collaboratively working with the regional farming interests to develop a mutually-beneficial project for future renewable water supplies for both the municipal water needs of Parker but also for the agricultural interests, represented by the Northeast Colorado Water Cooperative (NECWC), working through LSPWCD. The scope of the project area for this innovative water supply plan, showing the location of PWSD relative to its Logan County farms and the LSPWCD service area, is shown in Figure 2.
The two parties have been working together collaboratively to assess viable options to increase the beneficial use of the available water supplies in the Lower South Platte River basin. These options have included developing (a) both irrigation season and non-irrigation season water rights, (b) the means to provide substitute supplies to farmers to maintain historic irrigation water, (c) the use of existing storage for equalization from times of supply to times of need for both entities, (d) exchanges of water from downstream locations to upstream locations to obviate the need for pipelines, (e) new storage for the capture of unappropriated water, and (f) a pipeline delivery system to both Parker and for delivery back to the South Platte River at upstream locations for LSPWCD’s agricultural use.
To evaluate these options related to both technical and economic feasibility, a model has been developed by Lytle Water Solutions, LLC (LWS) to assess multiple options related to developing renewable water supplies both for PWSD and the NECWC/LSPWCD. This is a complex point-flow, exchange, and reservoir model to simulate the currently-occurring inflows and outflows along the Lower South Platte River in the reach of interest, along with the proposed actions that are part of the proposed long-term water supply plan. The model is being used to assess and quantify the parameters of the project. While the model is very complex, with multiple variables that have to be evaluated, the variables in the model have been set to a dashboard so the sensitivity of each variable can be assessed very quickly, i.e., within a matter of seconds. In our oral presentation the model’s capabilities will be demonstrated to show how facile it is to evaluate complex flow, storage, and water use issues.
Our next blog (Part 2) will provide the description of the project so there is the background to understand the workings of the model, which is described in Part 3 of this blog series.
If you have questions or would like additional information on creative solutions to water issues, please give us a call (303-350-4090) or send us an email at lws@lytlewater.com.
Bruce Lytle, P.E. bruce@lytlewater.com
Chris Fehn, P.E., P.G. chris@lytlewater.com
