Using innovative partnerships, the U.S. Army Corps of Engineers (USACE) is assisting the Oklahoma Water Resources Board (OWRB) in a five-year effort to update the Oklahoma Comprehensive Water Plan (OCWP). This effort includes a detailed assessment of the physical and legal availability of Oklahoma’s surface water and groundwater resources, integrated with water quality and infrastructure constraints, to meet the state’s water supply needs through 2060. Each of the major water-use sectors in the state is included in decadal water demand projections, and environmental flow programs also are being evaluated. By analyzing supplies, demands and water supply solutions for each of 82 watersheds across Oklahoma, this statewide planning promotes a secure water future at the local level, while serving as a national demonstration model with potential application to other states’ planning activities.
The update to the OCWP builds upon a wealth of information that has been developed by USACE, OWRB and other state, federal and local members of Oklahoma’s water community. The effort employs significant levels of state-federal collaboration. Two major differences between this update and previous state water plans are the detailed focus on evaluating water resources on a watershed basis and the inclusion of a robust public participation process. Other important differences include enhanced focus on understanding issues and challenges facing the water community and development of technical tools to support local entities and stakeholders in their planning.
The approach to the OCWP is both to pursue technical studies and develop policy recommendations to address current and emerging needs. This strategy will provide the best opportunity for collaborative solutions to the state’s current and future water needs.
Oklahoma’s water supplies are driven by the state’s diverse climate and are influenced by land use, geography and geology. The state’s central location in the United States results in a wide range of precipitation, with areas western Oklahoma receiving an annual average of about 16-in and the southeastern portion of the state receiving more than 50-in on average. As a result, the state’s water resources also vary significantly across Oklahoma’s broad hydrologic and ecologic regions.
Water supplies can be evaluated using myriad boundaries and geographic extents. To meet the OCWP planning objectives, supply analyses were developed on a watershed or “basin” basis, guided by the locations of surface water streamflow gauges and the availability of acceptable flow data. Similarly, the comparison of supplies and future demands to assess the potential for future shortages was conducted on a basin-level scale, requiring the projected water demands to be allocated among those same basins.
The statewide water analyses were performed on a geographic basis by subdividing the state into 82 surface water basins using United States Geological Survey Hydrologic Units 12 boundaries. The basins used for this analysis were adapted from existing OWRB stream system analysis boundaries. The basins were also aggregated into 13 regions to facilitate assessments of regional supply solutions.
Key drivers for water planning in Oklahoma include increased water demands as a result of population growth and increases in other water-use sectors, such as agriculture and energy development. The state’s population is expected to grow from 3.6 million in 2007 to 4.8 million in 2060.
Water demand projections for all major water uses in each of the 82 OCWP basins were developed for the 2007 base year, and then at 10-year intervals from 2010 to 2060. Water uses are grouped into four major categories—public-supplied municipal and industrial (M&I); self-supplied residential; self-supplied nonresidential; and agriculture—and further analyzed for seven sub-categories or “sectors.”
New Planning Tools
As a foundation of the OCWP technical work, a Microsoft Access database and geographic information systems (GIS)-based analysis tool was created to compare projected demands to physical supplies for each of the 82 OCWP basins. Called the Oklahoma H2O Tool, this model is being used in the planning process to identify areas of potential “wet water” shortages (physical supply constraints), enabling the modelers to more closely examine demands, supplies and potential water supply solutions. Developed to allow flexibility in performing “what-if” scenarios, the tool provides unprecedented capabilities to make informed decisions based on a variety of factors. The analysis compares the available surface water and groundwater in each OCWP basin to the demands on those sources.
The flexible watershed assessment approach and the OCWP analysis tools enable local, state and federal water planners to quickly consider, model and plan around uncertainties in the timing and magnitude of water supplies and demands. The results of the analyses, as well as the data and tools themselves, will be made available to water planners and users for their use in more detailed local planning efforts.
To evaluate public policy and technical merits of these and other topics, specific workgroups have been formed for analysis and dialogue. Examples of the workgroup topics include environmental flow management, aquifer recharge, use of marginal quality water supplies and conjunctive management. Discussion of these factors will help determine the potential solutions for each watershed now and into the future.
The Oklahoma H2O tool was designed with flexibility for analyses of uncertainties, such as the potential for climate change and potential infrastructure and water management solutions to meet future water needs. Examples of the types of questions and sensitivity analyses that can be addressed with the tool on a water-use sector, basin-specific, or statewide basis include:
- What if demands are higher or lower than the baseline projections?
- What if available water supplies are greater or lesser than the baseline projections?
- Could we utilize alternate water supplies to meet water demands and address projected shortages without creating shortages elsewhere?
- Would out-of-basin supplies help meet future demands? How much diversion, conveyance and storage capacity would be needed?
- How much would we need to reduce demands—temporarily during drought or permanently using conservation measures—to address potential future shortages?
A Model for State-Federal Partnerships
The OCWP is being developed through innovative partnerships between state and federal agencies. OWRB and USACE are the lead state and federal agencies, with each contributing 50 percent of project funding through cooperative agreements. Technical work on the OCWP was initiated in 2008, with OWRB and USACE co-funding activities by leveraging Planning Assistance to States and two General Investigation USACE authorities.
Other state and federal partners are contributing data, technical resources and expertise through in-kind assistance. The numerous state and federal partner agencies contributing data and resources include the Oklahoma Department of Environmental Quality, the Oklahoma Department of Agriculture, Oklahoma State University, USGS, the Bureau of Reclamation and many others. Together, this approach leverages resources and makes full use of the wealth of information that has been and continues to be developed by other water agencies and stakeholders.
To set the stage for long-term multi-organization cooperation and leveraging of technical resources and funds, OWRB is initiating an effort similar to the collaborative process underway by the Western States Water Council and the Western States Federal Agency Support Team (WestFAST). The WestFAST is composed of 11 federal agencies committed to collaboration and to leveraging technical resources to address water-related issues in the West. This Oklahoma-led initiative to engage the WestFAST process at the state level will benefit the ongoing OCWP update, associated follow-on detailed investigations and future updates. The initiative will serve as a national demonstration model with potential application to other states’ planning activities.
Together with the OCWP projections of supply, demand and shortages on a basin level of detail, the analysis tools and conceptual assessments of water supply solutions for each basin form a solid foundation for detailed local planning and implementation. This innovative, grassroots, state-led approach to water planning is being viewed as a model for planners nationwide. Armed with this unprecedented level of detail, tools and information, planners in Oklahoma are working toward a secure water future for all Oklahomans despite the myriad uncertainties that each user faces.