Drought

The USGS closely monitors the occurence and effects of drought through data collection and research. USGS science supports water managers in preparing for possible future drought by providing information about long-term hydrologic, climatic, and environmental changes. These studies support successful planning and science-based decision-making by water managers who must address complex issues and...

Drought is making the Delta Saltier. Less freshwater coming from watershed runoff and reservoir releases means that more salty water flows into the Sacramento San Joaquin Delta (Delta) from the Pacific Ocean. Changes in Delta salinity have far-reaching impacts, affecting the water supply for agriculture, drinking, wildlife, and Delta ecosystems.

The Upper Feather River Watershed is one of California’s regions of highest precipitation. Its runoff provides the majority of water delivered by the State Water Project, an average 3.2 million-acre feet each year feeding into Lake Oroville.

Soil moisture is a critical variable for understanding the impacts of drought on ecological, hydrological, and agricultural systems, as soil moisture content has a direct affect on runoff amounts. Runoff occurs as the result of precipitation (both rainfall and snowfall) that is in excess of the demands of evaporation from land surfaces, transpiration from vegetation, and infiltration into soils...

California's Sierra Nevada snowpack accounts for much of the water supply in many parts of the state. The snowpack retains large amounts of water in the winter that is then released as temperatures rise in the spring and summer. The snowpack also keeps the Sierra soil moist by covering it longer into spring and summer. Soil moisture influences the onset of wildfires, as well as wildfire prevalence...

As a result of climate change, heavy rainfall, as well as extended dry periods, are becoming more common in the Midwestern United States. These trends are only expected to continue. So, increasing the capacity of soil to store water has become more critical. Storing water increases availability in dry conditions. And the absorption of additional water in wet conditions reduces potential flooding...

Because the following information has immediate and time-sensitive relevance to public health and welfare owing to the Governor's declared drought emergency it is being released as preliminary information. As preliminary information, it had been reviewed and approved to meet the needs for timely best science, but the methodology is subject to refinement. The information is provided on the...

To create a framework for adapting to climate change, decision makers need to understand specific threats to our water supply, land use suitability, hazard risks, ecosystems and quality of life. A vulnerability assessment that defines the projected degree to which an ecosystem, landscape, or watershed is vulnerable to change will help to create this framework. Presently those who are open to...

The endeavor to ensure a viable population of the threatened wolverine to the mountains of California requires the characterization of suitable habitat.

The purpose of this study is to assess the distribution of water residence times across the central Delta using rapid water isotope measurements (δ2H, δ18O) made with a boat-based flow-through instrument.

Subsidence is a global problem and, in the United States, more than 17,000 square miles in 45 States, an area roughly the size of New Hampshire and Vermont combined, have been directly affected by subsidence. More than 80 percent of the identified subsidence in the United States is a consequence of human impact on subsurface water.

The San Joaquin Valley is one of the most productive agricultural regions in the nation. Beginning around the 1920's, farmers relied upon groundwater for water supply. Over time, overpumping caused groundwater-level declines and associated aquifer-system compaction and land subsidence that resulted in permanent aquifer-system storage loss.