South Lahontan

Flood-Hazard Study -- 100 Year Flood Stage for Lucerne Lake, San Bernardino County, California

U.S. Geological Survey (USGS) | July 15th, 1977

Flood-Hazard Study -- 100-Year Flood Stage for Apple Valley Dry Lake, San Bernardino County, California

U.S. Geological Survey (USGS) | June 30th, 1975

A study of the flood hydrology of Apple Valley, Calif., was undertaken to develop the 100—year flood stage for Apple Valley dry lake. Synthetic hydrologic techniques we

A study of the flood hydrology of Apple Valley, Calif., was undertaken to develop the 100—year flood stage for Apple Valley dry lake. Synthetic hydrologic techniques were used because no adequate hydrologic or meteorologic data were available for the basin. The 100—year flood stage was estimated to be at an elevation of 2,909.0 feet (886.7 metres) above mean sea level.

Flood-MAR Research and Data Development Plan

California Department of Water Resources (DWR) | October 31st, 2019

The Research Advisory Committee (RAC) is pleased to make this plan available to the growing network of farmers, researchers, planners, and water and land managers who wan

The Research Advisory Committee (RAC) is pleased to make this plan available to the growing network of farmers, researchers, planners, and water and land managers who want to expand our collective knowledge about using floodwaters for managed aquifer recharge (Flood-MAR). This plan outlines the priority information needed by those making management decisions about the where, when, and how of capturing available flood water to replenish California’s depleted aquifers.

Floods in California

Public Policy Institute of California (PPIC) | February 29th, 2024

Focused groundwater recharge in the Amargosa Desert basin

U.S. Geological Survey (USGS) | July 1st, 2007

 The Amargosa River is an approximately 300-kilometer-long regional drainage connecting the northern highlands on the Nevada Test Site in Nye County, Nev., to the floor

 The Amargosa River is an approximately 300-kilometer-long regional drainage connecting the northern highlands on the Nevada Test Site in Nye County, Nev., to the floor of Death Valley in Inyo County, Calif. Streamflow analysis indicates that the Amargosa Desert portion of the river is dry more than 98 percent of the time. Infiltration losses during ephemeral flows of the Amargosa River and Fortymile Wash provide the main sources of ground-water recharge on the desert-basin floor. The primary use of ground water is for irrigated agriculture. The current study examined ground-water recharge from ephemeral flows in the Amargosa River by using streamflow data and environmental tracers. The USGS streamflow-gaging station at Beatty, Nev., provided high-frequency data on base flow and storm runoff entering the basin during water years 1998–2001. Discharge into the basin during the four-year period totaled 3.03 million cubic meters, three quarters of which was base flow. Streambed temperature anomalies indicated the distribution of ephemeral flows and infiltration losses within the basin. Major storms that produced regional flow during the four-year period occurred in February 1998, during a strong El Niño that more than doubled annual precipitation, and in July 1999. The study also quantified recharge beneath undisturbed native vegetation and irrigation return flow beneath irrigated fields. Vertical profiles of water potential and environmental tracers in the unsaturated zone provided estimates of recharge beneath the river channel (0.04–0.09 meter per year) and irrigated fields (0.1–0.5 meter per year). Chloride mass-balance estimates indicate that 12–15 percent of channel infiltration becomes ground-water recharge, together with 9–22 percent of infiltrated irrigation. Profiles of potential and chloride beneath the dominant desert-shrub vegetation suggest that ground-water recharge has been negligible throughout most of the basin since at least the early Holocene. Surface-based electrical-resistivity imaging provided areal extension of borehole information from sampled profiles. These images indicate narrowly focused recharge beneath the Amargosa River channel, flanked by large tracts of recharge-free basin floor.

Forests and Water in the Sierra Nevada: Sierra Nevada Watershed Ecosystem Enhancement Project

University of California, Merced (UC Merced) | November 21st, 2011

In this white paper on the Sierra Nevada Watershed Ecosystem Enhancement Project (SWEEP), we make the case that upstream management of Sierra Nevada forests can significa

In this white paper on the Sierra Nevada Watershed Ecosystem Enhancement Project (SWEEP), we make the case that upstream management of Sierra Nevada forests can significantly increase the value of downstream water resources by shifting water towards higher value uses and optimizing the timing of runoff. The focus of this paper is on the west-side mixed-conifer forests at elevations of about 1500-3600 m (5000-12,000 ft), which are highly productive owing to the availability of sufficient water, predominance of above-freezing temperatures and presence of other conditions necessary for growth.  California has a Mediterranean climate, with wet winters and dry summers. Precipitation falling as rain on Sierra Nevada forests enters the soil and is partitioned between evapotranspiration and runoff. Much of the rainfall leaves the forest as evapotranspiration, owing to ample water storage in the subsurface and temperatures that allow growth year round. At higher elevations, e.g. above elevations of 1800-2100 m depending on both latitude and microclimate, which are dominated by snow rather than rain, the snowpack provides an important seasonal storage of water that, together with subsurface-water storage, provides the water needed for forest growth over the summer and fall. Forest thinning to reduce vegetation and thus evapotranspiration will result in a higher fraction of precipitation, particularly snowmelt, leaving the mountain forest as runoff. Historically, the unique character of Sierra Nevada forests was defined by its tall trees, relatively mild climate and low forest density. In many areas, current forest densities are much higher than historical values. Forest thinning can also influence the timing of snowmelt and runoff. That is, a less-dense canopy can allow snow to reach the ground rather than be held in the canopy; and strategic spacing of forest openings will limit early season sunlight reaching the forest floor and retard snowmelt.  In this paper we review the forest hydrology literature relevant to management of conifer forests in the Sierra snow zone, as that management affects the timing and amount of snowmelt runoff. In order to understand the conceptual and practical challenges, we summarize the key elements of forest energy budget, with specific reference to the Sierra Nevada, and describe several relevant case studies. Although principles that govern the mountain water cycle are well known and models of water and energy balance are informed by field measurements in some areas, there is a severe knowledge gap that limits quantitative predictions of the effects of forest thinning on Sierra Nevada water and energy cycles. Nevertheless, generalizations from reviews of paired catchment studies carried out elsewhere suggest that Sierra Nevada conifer forests contain ecological attributes with a high potential for water-yield gains. Historical studies of forest harvesting in the Sierra Nevada have shown increases of between 14 and 34% in snow accumulation. Treatments that increase snow accumulation help increase water yield during low flows, when water resources’ economic and ecosystem values are highest.  Preliminary estimates based on average climate information suggest that in the Sierra Nevada, treatments that would reduce forest cover by 40% of maximum levels across a watershed could increase water yields by about 9%. Note that this white paper focused on forest management effects on the water balance. Impacts on wildlife habitat, forest health, and fire behavior were not analyzed. The projections and models reported here are designed to describe the potential for modifying water yield and timing. Before implementation of any strategy, a wider consideration of the consequences on forest structure and function would be necessary.  Because of the potential for water-yield increases and extended snow storage, the SWEEP project has developed a plan to evaluate forest thinning related to water yield in representative headwater catchments in the Sierra Nevada, as a basis for extending these treatments to broader areas of the Sierra Nevada. To that end, we outline an experiment that could be carried out in the Onion Creek Experimental Forest, Tahoe National Forest, Placer County, California that could test silvicultural treatments designed to modify the water balance of mixed-conifer, snow-dominated catchments. The treatments are based on a leaf area index (LAI) approach (O’Hara 1998) to forest management, which is well-suited to water yield and timing objectives. Our initial estimates are that treatments could increase water yield as much as 16% and extend snow storage, i.e. delay snowmelt, by days to weeks. 

Fourth National Climate Assessment Chapter 25: Southwest

U.S. Global Change Research Program | November 23rd, 2018

The Southwest region encompasses diverse ecosystems, cultures, and economies, reflecting a broad range of climateconditions, including the hottest and driest climate in t

The Southwest region encompasses diverse ecosystems, cultures, and economies, reflecting a broad range of climateconditions, including the hottest and driest climate in the United States. Arizona, California, Colorado, New Mexico, Nevada, and Utah occupy one-fifth of U.S. land area, extending across globally unique ecosystems from the Sonoran Desert to the Sierra Nevada to the Pacific Coast. The region is home to 60 million people, with 9 out of 10 living in urban areas and the total population growing 30% faster than the national average. The Nation depends on the region for more than half of its specialty crops such as fruits, nuts, and vegetables. The Southwest also drives the U.S. technology sector, with more than 80% of the country’s technology capitalization located in California. Click here for all chapters of the Fourth National Climate Assessment.

Fourth National Climate Assessment Chapter 3: Water

U.S. Global Change Research Program | November 23rd, 2018

Significant changes in water quantity and quality are evident across the country. These changes, which are expected to persist, present an ongoing risk to coupled human

Significant changes in water quantity and quality are evident across the country. These changes, which are expected to persist, present an ongoing risk to coupled human and natural systems and related ecosystem services. Variable precipitation and rising temperature are intensifying droughts, increasing heavy downpours, and reducing snowpack. Reduced snow-to-rain ratios are leading to significant differences between the timing of water supply and demand. Groundwater depletion is exacerbating drought risk. Surface water quality is declining as water temperature increases and more frequent high-intensity rainfall events mobilize pollutants such as sediments and nutrients. Click here for the text of the full report.

Framework to Coordinate Water Quality Improvement and Wildlife Habitat Conservation to Protect California Streams, Wetlands and Riparian Areas

San Francisco Estuary Institute (SFEI) | February 1st, 2016

The emergence of comparable landscape approaches to wildlife conservation and water quality improvement through federal and California state regulatory and management pr

The emergence of comparable landscape approaches to wildlife conservation and water quality improvement through federal and California state regulatory and management programs provides an opportunity for their coordination to better protect California’s aquatic resources, especially streams, wetlands, and riparian areas. Such coordination is patently desirable. A framework has been developed to help coordinate restoration and compensatory mitigation across policies governing wildlife conservation and water quality in the landscape context. The framework is based on the Wetland and Riparian Area Monitoring Plan (WRAMP) of the California Wetland Monitoring Workgroup (CWMW) of the Water Quality Monitoring Council. The framework presented here is a version of the standard WRAMP framework. It only differs from the standard framework to better accommodate wildlife conservation planning, assessment and reporting. To distinguish this version from the standard version, it is termed theWRAMP for wildlife (WRAMPw).

Frequently Asked Questions Related to the CASGEM Program

California Department of Water Resources (DWR) | August 21st, 2023

Since 2009, the California Statewide Groundwater Elevation Monitoring (CASGEM) Program has tracked seasonal and long-term groundwater elevation trends in groundwater basi

Since 2009, the California Statewide Groundwater Elevation Monitoring (CASGEM) Program has tracked seasonal and long-term groundwater elevation trends in groundwater basins statewide. The program’s mission is to establish a permanent, locally-managed program of regular and systematic monitoring in all of California's alluvial groundwater basins. Senate Bill x7-6, passed by the legislature in 2009, established collaboration between local monitoring parties and DWR to collect statewide groundwater elevations, to be made available to the public. In response to the law, we developed the CASGEM program. Collecting and evaluating these groundwater data on a statewide scale is a fundamental step toward improving management of California's groundwater resources. The CASGEM program relies and builds upon the many previously established local long-term groundwater monitoring and management programs. Click here for the CASEGEM Data and Resources directory from the Department of Water Resources.