Water supplies in the western united states are heavily dependent on natural water storage in the mountain snowpack which stores tens of millions of acre feet of water annually

The Bureau of Reclamation awarded a $1,084,428 Cooperative Agreement to the Regents of the University of Colorado under the Snow Water Supply Forecasting program (CFDA 15.078) to develop a Surface Snow Water Equivalent Data Fusion System (SWE-Fusion) for the western United States. The primary objective is to provide improved surface snow water equivalent estimates to enable better decision-making during anomalous hydrologic conditions like drought and flooding. The University will combine historical satellite, model-based, ground-based, and airborne snow observations from 2000 through 2026 to produce weekly historical and real-time snowpack data products. These will be integrated with existing water supply forecasting procedures and decision-making processes through partnerships with state and federal agencies across the western U.S.

Snowmelt from this natural storage fills reservoirs across the region. Demands on these sources of water storage meet or exceed supply under large portions of the west. The recent droughts in california and in the colorado river basin, significantly reduced this natural water storage leading to significant water supply-demand imbalances that have had profound economic and societal impacts. Despite the considerable attention focused on drought in the west, little work has been done to evaluate the degree to which new snow data sources can mitigate impacts through improved information and decision making. The proposed work will develop a surface snow water equivalent data fusion system (SWE-fusion) for the western united states using a combination of historical snow water equivalent satellite model-based snow water equivalent reanalyses, ground-based snopack telemetry data (snotel), and when available, airborne snow observations from 2000 through the funding cycle (i.e. 2026) the primary objective of this research is to provide improved surface snow water equivalent estimates for the region and enable improved decision making during anomalous hydrologic conditions (e.g. drought and rain-on-snow flooding). Related secondary and tertiary objectives aim to migrate remotely sensed surface snow water equivalent analyses into operational computational environments with the national resources conservation service (nrcs) and the national weather service (NWS) river forecast centers and to conduct quantitative and qualitative assessment of the utility of the snow water equivalent - fusion snowpack information with regard to informing water resource decisions. The following questions will be addressed:1. Can snowpack information from surface snow water equivalent (SWE-fusion) improve water resource decision making under anomalous hydrologic conditions 2. Are relative improvements to water supply information, provided by snow water equivalent-fusion, greater during anomalous conditions such as the current southwest drought 3. What is the utility of snow water equivalent - fusion snowpack information for water resource decision making the proposed work is highly relevant to this announcement in that we will characterize anomalies in water supply using a combination of the national aeronautics and space administration (NASA) and the united states geological survey (USGS) satellite observations, physically based land surface models, ground-based, and airborne data (when available). The primary deliverable will be weekly (JAN - may, 2000 - 2021) historical surface snow water equivalent data for the western united states and real time BI-weekly and weekly surface snow water equivalent (SWE) data for the 2025 and 2026 snow seasons (JAN - may). These efforts will be directly linked to existing water supply forecast procedures and relevant decisions which derive from these forecasts. Our existing partnerships with california department of water resources (CA-DWR), reclamation, national weather service colorado basin river forecast center (NWS-cbrfc), national weather service california nevada river forecast center (NWS-cnrfc) and stakeholders across the west will ensure the integration of the project results into the decision-making process.