North Lahontan

California Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project: Domestic-Supply Assessment

U.S. Geological Survey (USGS) | March 14th, 2024

California Groundwater Conditions Update – Spring 2019

California Department of Water Resources (DWR) | October 3rd, 2022

DWR has completed an evaluation of state-wide groundwater level data reported in spring 2019 for California groundwater basins. Spring data correspond to the time period

DWR has completed an evaluation of state-wide groundwater level data reported in spring 2019 for California groundwater basins. Spring data correspond to the time period immediately before the typical irrigation season begins in a region. This helps show groundwater levels before summer crop irrigation and other uses. In Central and Northern California, the pre-irrigation season is in March, while in Southern California, that season is typically earlier. The Spring 2019 Groundwater Level Data Coverage map (Figure 1) shows a comparison between total spring 2019 reporting and typical reporting in previous years. Typical reporting includes wells with water level data submitted to DWR over the past five spring seasons (2015-2019) by CASGEM Monitoring Entities, other local agencies, and well owners. Although the reporting percentage is high and coverage is good, there are still gaps in spring 2019 coverage throughout the state, including portions of Tulare, Kern, San Bernardino, Riverside, and Imperial counties.

California Groundwater Conditions Update – Spring 2020

California Department of Water Resources (DWR) | October 3rd, 2022

In this report, groundwater level change values compare spring 2020 to spring 2019, 2017, 2015, and 2010. The information is summarized in Table 1. Spring groundwater lev

In this report, groundwater level change values compare spring 2020 to spring 2019, 2017, 2015, and 2010. The information is summarized in Table 1. Spring groundwater level data are an important indicator of groundwater conditions because spring generally corresponds to the pre-irrigation season. This time period is representative of the water year’s peak groundwater levels. Associated maps display groundwater level increases and decreases and summarize data by hydrologic region.

California Groundwater Conditions Update – Spring 2021 California’s drought and groundwater

California Department of Water Resources (DWR) | October 3rd, 2022

This report uses maps to depict how groundwater levels have changed over time using two different analytical methods. One method, groundwater level change maps, show the

This report uses maps to depict how groundwater levels have changed over time using two different analytical methods. One method, groundwater level change maps, show the change in groundwater levels between two different springtime measurements. The second method uses trend analysis of water levels for wells having at least 10 annual springtime measurements over a 20-year period to illustrate the statistical magnitude and direction of groundwater level change (a well’s water level increasing or decreasing trend over time). Spring groundwater level data are an important indicator of groundwater conditions because spring generally corresponds to both the pre-irrigation season and the peak groundwater levels in a water year.

California Water Plan 2013: North Lahontan Hydrologic Region

California Department of Water Resources (DWR) | October 30th, 2016

The North Lahontan Hydrologic Region (North Lahontan region) includes part of the western edge of the Great Basin, a large landlocked area that covers most of Nevada and

The North Lahontan Hydrologic Region (North Lahontan region) includes part of the western edge of the Great Basin, a large landlocked area that covers most of Nevada and northern Utah. The eastern drainages of the Cascade Range and the eastern Sierra Nevada, north of the Mono Lake drainage, make up the region. All surface water drains eastward toward Nevada. This hydrologic region extends about 270 miles from the Oregon border to the southern boundary of the Walker River drainage in Mono County (Figure NL-1). The region covers 6,122 square miles, about 4 percent of California’s total area, but is inhabited by only about 0.3 percent of the state’s population. The region includes portions of Modoc, Lassen, Sierra, Nevada, Placer, El Dorado, Alpine, and Mono counties. The region abounds with large, natural landscapes. The northern part is primarily arid high desert with relatively flat valleys at elevations of 4,000 to 5,000 feet. The eastern slopes of the Sierra Nevada comprise the central and southern portions of this region, which includes the California portion of the Lake Tahoe Basin and the western Great Basin.  The major rivers of the region —Truckee, Carson, and Walker — carry the mountain snowmelt through California into Nevada. Mountain peaks up to 12,279 feet from the western boundary of the region.

California Water Plan Update 2018, Supporting Documentation for Water Portfolios

California Department of Water Resources (DWR) | April 15th, 2019

California Water Plan Update 2018 (Update 2018) supporting documentation for water portfolios includes descriptions and accountings of water uses and their supplies for t

California Water Plan Update 2018 (Update 2018) supporting documentation for water portfolios includes descriptions and accountings of water uses and their supplies for the state in Figures 1 and 5, and for 10 hydrologic regions in Figures 7 through 16. They include pictures of conditions in California, along with water balance data for Water Years (WYs) 2011–2015. Regional inflow and outflow Figures 17 and 18 provide a geographic overview of California and surface water inflows and outflows with adjoining states, between hydrologic regions, and to the Pacific Ocean, for a wet year between two drought sequences, and a critically dry year in a drought sequence. More extreme and variable hydrology seems to have become the new normal, and not just for California. California has been, and will continue to be, a useful example of extremes brought on by a wide variety of climates and terrains. To better understand these diversities, plan for future needs, and move toward water resources sustainability, the California Department of Water Resources (DWR) analyzes water use and supply conditions for each water year at various spatial scales for the entire state. This accounting of water uses and supplies is the only statewide analysis that exists. The California Water Plan (Water Plan) water balance data is used by many in and out of the water community. Data and information requests come from other DWR programs, State and federal agencies, cities and counties, local water agencies and purveyors, research institutes, universities, non-governmental organizations, private sector companies, lawyers, elected officials, news media, documentaries, book writers, students, interested public, other states, and even other countries because California is recognized as a leader in integrated water resources management. The following excerpt is from Update 2018, Chapter 1, “California Water Today,” section on California’s Diverse Water Supplies and Uses.

California Water Plan Update 2023 (Final Version)

California Department of Water Resources (DWR) | April 3rd, 2024

Updated every five years, the Water Plan is the State’s strategic plan for sustainably and equitably managing, developing, and stewarding water resources. Required by W

Updated every five years, the Water Plan is the State’s strategic plan for sustainably and equitably managing, developing, and stewarding water resources. Required by Water Code Section 10005, the plan presents the status and trends of California’s water-dependent natural resources; water supplies; and agricultural, urban, and environmental water demands for a range of plausible future scenarios.

California Water Plan Update 2023 Public Review Draft

California Department of Water Resources (DWR) | September 20th, 2023

The California Water Plan (Water Plan), updated every five years, is the State’s strategic plan for sustainably and equitably managing, developing, and stewarding water

The California Water Plan (Water Plan), updated every five years, is the State’s strategic plan for sustainably and equitably managing, developing, and stewarding water resources. Required by Water Code Section 10005, the plan presents the status and trends of California’s water-dependent natural resources; water supplies; and agricultural, urban, and environmental water demands for a range of plausible future scenarios.

California Water Resilience Portfolio

State of California | July 28th, 2020

California Wetland and Riparian Area Protection Policy Technical Memorandum No. 5: Stream Definition

San Francisco Estuary Institute (SFEI) | April 20th, 2016

With this memorandum, the Technical Advisory Team (TAT) recommends a definition of California streams to the Policy Development Team (PDT) of the State Water Quality Cont

With this memorandum, the Technical Advisory Team (TAT) recommends a definition of California streams to the Policy Development Team (PDT) of the State Water Quality Control Board (State Water Board) for its Wetland and Riparian Area Protection Policy (WRAPP). This memorandum does not recommend any process or procedure for identifying, delineating, or classifying streams, nor are such recommendations being planned by the TAT at this time. However, the TAT recommends that such processes and procedures should be developed in the future to support the WRAPP. The California Wetland Monitoring Workgroup (CWMW) is preparing recommendations for stream mapping as part of the recommending methodology of the California Aquatic Resource Inventory (CARI).