Under Construction
The WSWC is developing a new Western Water Conservation Application Tool (WestCAT) that would streamline operations for voluntary compensated, in-state, and temporary water conservation programs. Measures might include full-season fallowing, alternative irrigation strategies, and crop switching. WestCAT will integrate two foundational data sets for water conservation: (1) water rights from the Western States Water Data Access and Analysis Tool (WestDAAT); and (2) evapotranspiration (ET) data as a proxy for consumptive use estimates using remote sensing technology through OpenET. Conservation and optimization measures and water markets are key strategies to manage scarce water in the Western United States.
WestCAT could support different communities including: (1) Users, or conservation applicants, would most likely be agricultural interests such as farmers and ranchers with irrigated acreage, but could also be municipal or other interests with substantial irrigated lands or turf; (2) a program sponsor designated as the Conservation Organization, which might include river basin authorities, boards or commissions, state or federal agencies, municipalities, water districts, canal companies, environmental organizations, or others willing to fund conservation programs; and (3) Technical Reviewers, which may be in-house staff or outside consultants, or state water right administrators evaluating related transfer applications. Access to information might also be provided to irrigation districts, water districts, canal companies or others that are not applicants or program sponsors, but that may be affected by transfers.
The WSWC created WestDAAT to be a user-friendly web-based tool that streamlines access to about 2.5 million surface water and groundwater rights and related data across the West. Each water right has a landing page with common key metadata and a direct link to public state water rights data, offering additional unique metadata and documents for that water right.
Measuring and monitoring ET on irrigated lands using satellite-based remote sensing has increased over the past couple of decades. OpenET provides a user-friendly imagery-based computational estimate of the total amount of water transferred from vegetation and the land surface to the atmosphere through evapotranspiration (ET). OpenET provides a single “ensemble value” from six satellite-data-driven models.
Each model currently uses Landsat satellite data to produce ET data at a spatial resolution of 30 meters by 30 meters (0.22 acres per pixel). OpenET data is available through an Application Programming Interface (API) that allows programmatic access to ET data for any field or other prescribed boundary. Any one of the OpenET ensemble models may also be used separately.
Western state water laws are based on reasonable beneficial use of a public resource for defined purposes, and once perfected (put to use) the water rights are considered private property rights. Uses may be consumptive and non-consumptive. Waste or unreasonable use of water is prohibited.
Evapotranspiration (ET) includes evaporation and transpiration from crops that consume water, which often serves as a useful but only partial proxy for reasonable beneficial use. Most owners or managers of irrigated lands in the West do not directly measure consumptive use, which is a critical element of water budgeting. Consumptive use includes ET, but also carriage losses from on and off-farm distribution systems, reservoir evaporation, and other irrecoverable water losses, not available for later use, such as deep percolation and outflows to the ocean or terminal lakes.
Total field ET is a function of both effective precipitation and supplementary irrigation. WestCAT is designed to subtract the effective precipitation from the total ET, resulting in a Net ET estimate. Net ET serves as a proxy for reasonable beneficial/consumptive use. The effective precipitation can be approximately calculated from the ET measurements from nearby non-irrigated land. For compensation for conserved water as measured using this tool, consumptive use includes only Net ET and does not include carriage losses or storage losses. OpenET can provide five-year historical estimates of ET for irrigated fields across the 17 Reclamation States.
Connecting water rights data with consumptive use estimates through WestDAAT and OpenET is expected to help promote federal, state, local, and regional water security and drought resilience activities by enabling and empowering individual Users (farmers and ranchers) to consider whether or not to participate in voluntary compensated conservation programs. WestCAT is also designed to allow a defined Conservation Organization to evaluate and apply conservation savings for designated purposes, consistent with state water law, while protecting farming and ranching activities longterm. Again, it is designed to promote and facilitate different conservation scenarios that fit local needs by providing water rights information in concert with water use data.
WestCAT will allow a Conservation Organization to set rules to evaluate an applicant’s historical consumptive use by defining the following parameters: (a) the OpenET model, ensemble or other consumptive use model(s) to use; (b) the period of time (i.e., number of years and start and end months) used to evaluate historical consumptive use; (c) the minimum or maximum number of eligible acres; and (d) the amount of compensation in U.S. dollars per acre or per acre-foot of conserved water offered a user. WestCAT will allow the Conservation Organization staff to quickly view all applications across a watershed (and different States if applicable), track their status in the technical review process, and see the total requested compensation and potential saved water volume.
WestCAT will allow a Technical Reviewer to access and review all submitted applications, add comments, and edit applications for accuracy (if needed). The Reviewer may also communicate with the state water rights administration agency or an affected irrigation district or canal company to verify the User (applicant) actually owns and controls the water right or water shares and is eligible to enter into an agreement with the Conservation Organization. There may be some conservation activities that require state consent and cooperation, such as protecting instream flow. The Technical Reviewer can add comments and suggestions, and finally change the application status (e.g., under review, recommend, reject).
WestCAT’s use will require registration to ensure Users, the Conservation Organization and Technical Reviewers are aware of its capabilities and limitations, particularly the need to understand and comply with state water laws and administrative rules, as well as protect the privacy of Users (applicants).