Drought Tools and Methods
The State Water Board developed the Water Unavailability Methodology for the Delta Watershed (Water Unavailability Methodology for short) to identify when supply and demand data indicate that water is unavailable for diversion by water right holders. The Water Unavailability Methodology identifies which diverters in the Delta watershed may face insufficient water supplies based on their priorities of right.
- Water Unavailability Workshop (video)
The Water Supply and Demand Visualization Tool is intended for informational purposes and will not be used to make water allocation or shortage decisions. This interactive tool shows basic monthly water balance data for past years in major watersheds throughout California at the HUC-8 (~700 square miles) scale. The tool allows users to compare different water supply and demand scenarios side-by-side, includes an interactive map of diversion points, and provides a detailed list of all water rights within the user-selected watershed. The State Water Board will add more watersheds and improve ease of use in the coming months.
As we continue to develop this tool, we want your feedback; please submit your ideas by visiting the tool clicking on the “About/Help” tab at the top of the page, and selecting “Report Bugs/Data Issues” from the dropdown menu.
See our Frequently Asked Questions for more on the Water Supply Demand Visualization Tool.
The State Water Board conducted a water demand data assessment to address data quality issues and improve how water use data is collected, reviewed, and processed. Water right holders are required to report how much water they use each year, but the reports we receive vary in terms of quality, making it difficult to incorporate the data into watershed-scale planning. The State Water Board streamlined how we compile and review this data and developed a set of protocols and requirements to process the data. The Water Rights Demand Data Analysis Methodology is a series of data pre-processing steps, R Scripts, and Data Processing Modules that identify and help address data quality issues related to both the self-reported water diversion and use data from water right holders or their agents and the Division of Water Rights electronic water rights data.
Initial Hydrology Modeling
The State Water Board is developing tools and methods to estimate yearly hydrology, create an initial planning forecast, and evaluate water supply at the sub-watershed scale. Components will consist of a tool that models initial supply conditions at a watershed scale in the Eel River and the Russian River, and a report that documents and standardizes the steps, processes, and datasets (and sources) used to model supply.
Water Allocation Tool
The State Water Board Division of Water Rights developed a Water Allocation Tool based upon the UC Davis Drought Water Rights Allocation Tool (DWRAT). The Tool incorporates geography, water supply, and the California water rights priority system into water availability analysis and drought curtailment decisions. The Water Rights Demand Data Analysis and Hydrology Modeling provide the data inputs used. The Allocation Tool was implemented in the Russian River Watershed to inform stream management decisions and water right curtailments in support of the drought emergency regulation. To further explore the implementation in water availability determinations, please visit the Russian River Drought Response page.