Research Counts

By Jennifer L. Rapp and Oronde Drakes

People depend on a clean, accessible supply of water to support their well-being, operate industries, grow food, and nourish the environment. Yet, for many places in the United States, there is an imbalance between the amount of water people demand and the amount of water that nature can reliably supply.

Water scarcity is an increasingly pressing issue, which can benefit from more robust scientific data on water supply, quality, and consumption across the nation. This information is critical to help communities plan for dry periods and build resilience, but it can be difficult to obtain data on the places and people most vulnerable to water stress.

Understanding Water Scarcity

Making water data more centralized and accessible has been a recent focus on the U.S. Geological Survey (USGS). In 2025, the agency released the National Water Availability Assessment, a comprehensive study quantifying the nation’s water availability. The information in this assessment can be used to identify and mitigate emerging imbalances between water supply and demand and help support water management decisions in the future.

Many of the people who rely on water data are local government officials, planners, and organizations who make daily water management decisions. Some may not have the financial and technical resources they need to collect and analyze their own information. The National Water Availability Assessment Data Companion tool, a user-friendly web platform, provides access to a curated, consistent set of USGS model outputs detailing historic water availability conditions across the lower 48 states. This tool helps users understand the dynamics of water availability in their region.

Comparing water supply and demand can provide insights on how water scarcity originates, potential risks associated with additional use, or likely effects of water conservation. For instance, in dry regions like the central High Plains—which spans parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming—a large percentage of local rainfall goes toward water consumption.  

As shown in the 10-year regional averages in the figure, there are many such places across the United States where there is a narrow margin between water demand and the amount of surface water available. As a result, communities may rely on water that is transported over long distances or drawn from deep groundwater reserves, which can be slow to replenish and, when depleted, may have reduced storage capacity or become salty.  In times when natural rainfall is below normal, these places are especially vulnerable to disruptions in their water supply. These aren’t abstract trends—they are realities that affect agriculture, health care systems, and ecosystems.

Building Resilience by Managing Water Supply

The USGS Supply and Use Index (SUI), a tool available in the Data Companion, is designed to help users understand the balance between their local water supply and demand. The SUI compares long-term natural water supply approximated by streamflow over a 10 year period, with consumptive use—the amount of water that is incorporated in products or crops, consumed by humans or livestock, or otherwise lost to evaporation or transpiration—to identify where and when water stress is most severe. The burgundy and orange areas on the map represent places where water limitations are severe or chronically high.

About 26.7 million people live in these high-stress watersheds, and many are among the most socially vulnerable. In fact, more than half of the 9 million people living in severe SUI areas are also considered highly socially vulnerable based on their socioeconomic status, household characteristics, racial and ethnic minority status, and/or housing type and transportation, according to the U.S. Centers for Disease Control and Prevention’s Social Vulnerability Index for 2020. These communities are at greater risk of running out of water and of the cascading impacts on health, livelihoods, housing, and environment.

By examining extensive historic drought periods, the SUI helps to pinpoint where the greatest impacts of water stress could occur in the future. This work doesn’t just identify problem areas; it also gives decision makers information that can be used for water management decisions, like developing more robust drought preparedness plans or issuing water supply permits for new housing or industry. With the National Water Availability Assessment Data Companion, users can access monthly data, explore seasonal patterns, and understand regional nuances that might not fit the national trend. This level of detail matters because water stress may not be uniform. California’s Central Valley, for example, can shift substantially between wet and dry seasons, creating unique challenges for water managers.

Planning for People

Planning for water hazards isn’t just about hydrology—it’s about people. The SUI and related water supply and demand datasets give users the ability to anticipate where water stress may hit the hardest, and which population centers and groups may be most affected. It can help communities build resilience, prioritize resources, and make informed decisions before the next potential drought. Tools such as these are particularly valuable in areas where local officials lack the capacity to independently collect and analyze the data they need to protect the most at-risk communities. As water scarcity is experienced by more communities, these data can make all the difference.