Hydroclimate Report Water Year 2021

California Department of Water Resources (DWR) | December 31st, 2022

Water year (WY) 2021 added to the climate change narrative with extreme dryness leading to record setting drought conditions. In both precipitation and temperature, there

Water year (WY) 2021 added to the climate change narrative with extreme dryness leading to record setting drought conditions. In both precipitation and temperature, there were new extremes with a record dry and warm spring being most notable. Late fall onset occurred again this year arriving in late November starting the seasonal snowpack on very dry soils. The WY ended with 48 percent of average precipitation statewide making it the second driest year in 126 years of record. It was also second warmest for statewide average temperature. For two-year totals, WY 2021 set a record, recording less precipitation than WY 1977. There was only one significant storm in the WY in late January which included low elevation snow and very strong damaging winds. The April 1 statewide snowpack registered 62% of average. Peak snowpack at 64% of average occurred the week before April 1. Runoff from the snowpack was far below expectations due to the dry antecedent conditions and record dry and warm spring. The lack of runoff resulted in the need for emergency drought response measures.

Hydroclimate Variability in Snow-fed River Systems

American Meteorological Society (AMS) | June 25th, 2019

Snow-fed river system communities are highly sensitive to climate change because the majority of their water supply is derived from snow. A warmer climate shift

Snow-fed river system communities are highly sensitive to climate change because the majority of their water supply is derived from snow. A warmer climate shifts precipitation phase from snow to rain, altering snowpack dynamics, shifting peak streamflow timing, reducing groundwater recharge, and increasing winter and spring flooding. Warmer spring and summer temperatures further compound these “snow droughts” by increasing evapotranspiration rates and irrigation water demand. This presents critical challenges in managing seasonal water supply and demand engineered for stationary climate patterns.

Hydrogeologic Evaluation - Proposed Regional Recharge and Recovery Project Mojave River Chanel Area

Mojave Water Agency (MWA) | August 15th, 2008

Provided in this report are the findings and conclusions of our hydrogeologic evaluation of the proposed Regional Recharge and Recovery Project (known herein as the R3 Pr

Provided in this report are the findings and conclusions of our hydrogeologic evaluation of the proposed Regional Recharge and Recovery Project (known herein as the R3 Project) that is to be located along/near the channel of the Mojave River in the vicinity of Hesperia, San Bernardino County, California. The R3 Project is to ultimately involve the construction of a put-and-take series of wells and transmission pipelines and the use of existing and proposed artificial spreading basins (mainly along the upper reach of the Mojave River).

Hydrogeologic evaluation and numerical simulation of the Death Valley regional ground-water flow system, Nevada and California

U.S. Geological Survey (USGS) | July 1st, 1997

Hydrogeologic Investigation Arroyo Seco Cone

Monterey County Water Resources Agency (MCWRA) | April 15th, 1994

This report presents the findings, analysis, conclusions, and recommendations developed as part of an investigation to characterize the hydrogeology of the Arroyo Seco Co

This report presents the findings, analysis, conclusions, and recommendations developed as part of an investigation to characterize the hydrogeology of the Arroyo Seco Cone area of the Salinas Valley. The purpose of this investigation is to assess the feasibility of developing a seasonal surface water spreading operation utilizing water diverted from the Arroyo Seco in order to enhance ground water recharge in the area. The goal of a project to store water in the ground for subsequent pumping and use is to increase the yield of the Salinas Basin. This investigation defines the hydrogeologic characteristics of the Arroyo Seco Cone area, characterizes the hydrology of the Arroyo Seco and the availability of divertable flows, and estimates the annual recharge that could be achieved through the development of spreading basins.

Hydrogeology and Simulation of Groundwater Flow in the Lucerne Valley Groundwater Basin, California

U.S. Geological Survey (USGS) | June 28th, 2022

The Lucerne Valley is in the southwestern part of the Mojave Desert and is about 75 miles northeast of Los Angeles, California. The Lucerne Valley groundwater basin encom

The Lucerne Valley is in the southwestern part of the Mojave Desert and is about 75 miles northeast of Los Angeles, California. The Lucerne Valley groundwater basin encompasses about 230 square miles and is separated from the Upper Mojave Valley groundwater basin by splays of the Helendale Fault. Since its settlement, groundwater has been the primary source of water for agricultural, industrial, municipal, and domestic uses. Groundwater withdrawal from pumping has exceeded the amount of water recharged to the basin, causing groundwater declines of more than 100 feet between 1917 and 2016 in the center of the basin. The continued withdrawal has resulted in an increase in pumping costs, reduced well efficiency, and land subsidence near Lucerne Lake. Although the volume of pumping has declined in recent years, there is concern that new agricultural growth and limits on imported water will continue to strain the sustainability of the groundwater system.

Hydrogeology and Water Resources of the Los Osos Valley Ground-Water Basin, San Luis Obispo County, California

U.S. Geological Survey (USGS) | July 18th, 1988

The Los Osos Valley ground-water basin is located on the coast of central California. It extends about 3 miles inland and an unknown distance offshore, where it is in h

The Los Osos Valley ground-water basin is located on the coast of central California. It extends about 3 miles inland and an unknown distance offshore, where it is in hydraulic connection with the Pacific Ocean. Its maximum onshore depth is about 1,000 feet. Ground-water flow in the basin was investigated using existing data, geologic mapping, drilling and measurements of potentiometric head, water quality, and streamflow. The basin is underlain largely by relatively impermeable rocks of the Franciscan Complex. Basin fill consists of unconsolidated, complexly layered sediments of Miocene age or younger. Individual beds are generally thin and discontinuous. A three-dimensional digital model of the basin was developed and calibrated to match potentiometric heads and head-dependent flows during water years 1970-77 and 1986. The model simulated poorly the steep vertical potentiometric heads, and it could not simulate perched water tables. In other respects, model results were good and not highly sensitive to likely errors in input data. Infiltrated rainfall contributes about 80 percent of annual recharge to the ground-water basin, and ground-water inflow accounts for almost all the remainder. Net recharge from Los Osos Creek is small. In water year 1986, outflow from the basin consisted of net municipal pumpage (24 percent), net agricultural pumpage (25 percent), net outflow across the ocean boundary (26 percent), perched-water runoff (16 percent), and phreatophyte transpiration (9 percent). During water years 1970-77 net municipal pumpage and net agricultural pumpage accounted for only 10 and 22 percent of total outflow, respectively. The population of Los Osos Valley is expected to increase by about 20,000 people by the year 2010, and municipal water use is expected to increase by about 1,700 acre-feet per year. The model was used to simulate the effects of various future water-supply and wastewater-disposal alternatives on the  ground-water system. Results indicated that if wastewater is centrally treated and recharged to the ground-water basin, the entire projected municipal water demand can be met with locally pumped ground water without inducing seawater intrusion, even during droughts lasting 1 to 3 years. If wastewater is exported from the basin, however, large amounts of seawater intrusion are likely to occur even if nearly half of the municipal water demand is met with imported water.

Hydrologic Analysis of Mojave River Basin, California, Using Electric Analog Model

U.S. Geological Survey (USGS) | August 18th, 1971

Hydrologic and geochemical characterization of the Petaluma River watershed, Sonoma County, California

U.S. Geological Survey (USGS) | January 31st, 2022

Principal water agencies in the Petaluma Valley groundwater basin seek to understand the availability of groundwater to meet increasing regional water supply demand cause

Principal water agencies in the Petaluma Valley groundwater basin seek to understand the availability of groundwater to meet increasing regional water supply demand caused by increasing agricultural and urban water demands. Surface water from the Russian River is the primary water supply in the basin, but the future availability of this surface-water supply is uncertain. Groundwater is an important supplemental source of water for the City of Petaluma and the primary supply for agriculture and domestic use by rural property owners. Furthermore, supplies of recycled water are becoming more available. Water managers face the challenge of meeting increasing water demand with a combination of surface water, local groundwater resources, and use of recycled wastewater. In 2014, California adopted legislation to manage groundwater: the Sustainable Groundwater Management Act (SGMA). The SGMA requires the development and implementation of Groundwater Sustainability Plans (GSPs) in 127 medium- or high-priority groundwater basins, and the Petaluma Valley groundwater basin was designated as a high-priority basin. Sustainability is defined within the SGMA in terms of avoiding undesirable results: significant and unreasonable groundwater-level declines, reduction in groundwater storage, seawater intrusion, water-quality degradation, land subsidence, and surface-water depletion. The U.S. Geological Survey (USGS), in cooperation with the Sonoma County Water Agency (SCWA) and the City of Petaluma, characterized the hydrology of the Petaluma valley watershed (PVW) and developed an integrated hydrologic model that can be used to improve understanding and management of the groundwater system and develop a GSP. The objectives of the study are to (1) develop an updated assessment of the hydrogeology and geochemistry of the PVW and (2) develop an integrated hydrologic model for the PVW. The purpose of this report is to describe the conceptual model of the hydrologic, hydrogeologic, and water-quality characteristics of the PVW and a numerical groundwater-flow model of PVW.

Hydrologic framework of the Santa Clara Valley, California

Geological Society of America (GSA) | June 1st, 2015

The hydrologic framework of the Santa Clara Valley in northern California was redefined on the basis of new data and a new hydrologic model. The regional groundwater flow

The hydrologic framework of the Santa Clara Valley in northern California was redefined on the basis of new data and a new hydrologic model. The regional groundwater flow systems can be subdivided into upper-aquifer and lower-aquifer systems that form a convergent flow system within a basin bounded by mountains and hills on three sides and discharge to pumping wells and the southern San Francisco Bay. Faults also control the flow of groundwater within the Santa Clara Valley and subdivide the aquifer system into three subregions. After decades of development and groundwater depletion that resulted in substantial land subsidence, Santa Clara Valley Water District (SCVWD) and the local water purveyors have refilled the basin through conservation and importation of water for direct use and artificial recharge. The natural flow system has been altered by extensive development with flow paths toward major well fields. Climate has not only affected the cycles of sedimentation during the glacial periods over the past million years, but interannual to interdecadal climate cycles also have affected the supply and demand components of the natural and anthropogenic inflows and outflows of water in the valley. Streamflow has been affected by development of the aquifer system and regulated flow from reservoirs, as well as conjunctive use of groundwater and surface water. Interaquifer flow through water- supply wells screened across multiple aquifers is an important component to the flow of groundwater and recapture of artificial recharge in the Santa Clara Valley. Wellbore flow and depth-dependent chemical and isotopic data indicate that flow into wells from multiple aquifers, as well as capture of artificial recharge by pumping of water- supply wells, predominantly is occurring in the upper 500 ft (152 m) of the aquifer system. Artificial recharge represents about one-half of the inflow of water into the valley for the period 1970–1999. Most subsidence is occurring below 250 ft (76 m), and most pumpage occurs within the upper-aquifer system between 300 and 650 ft (between 91 and 198 m) below land surface. Overall, the natural quality of most groundwater in the Santa Clara Valley is good. Isotopic data indicate that artificial recharge is occurring throughout the shallower parts of the upper-aquifer system and that recent recharge (less than 50 yr old) occurs throughout most of the basin in the upper-aquifer system, but many of the wells in the center of the basin with deeper well screens do not contain tritium and recent recharge. Age dates indicate that the groundwater in the upper-aquifer system generally is less than 2000 yr old, and groundwater in the lower-aquifer system generally ranges from 16,700 to 39,900 yr old. Depth-dependent sampling indicates that wellbores are the main path for vertical flow between aquifer layers. Isotopic data indicate as much as 60% of water pumped from production wells originated as artificial recharge. Shallow aquifers not only contain more recent recharge but may be more susceptible to anthropogenic and natural contamination, as evidenced by trace occurrences of iron, nitrate, and volatile organic compounds (VOCs) in selected water-supply wells. Water-resource management issues are centered on sustaining a reliable and good-quality source of water to the residents and industries of the valley. While the basin has been refilled, increased demand owing to growth and droughts could result in renewed storage depletion and the related potential adverse effects of land subsidence and seawater intrusion. The new hydrologic model demonstrates the importance of the aquifer layering, faults, and stream channels in relation to groundwater flow and infiltration of recharge. This model provides a means to analyze water resource issues because it separates the supply and demand components of the inflows and outflows.