2017 Salinas Valley Groundwater Level Contours & Seawater Intrusion Maps

Monterey County Water Resources Agency (MCWRA) | April 24th, 2018

2020 Annual Report on the Salton Sea Management Program

California Natural Resources Agency | February 21st, 2020

Improving air quality and creating habitat at the Salton Sea are key priorities for Governor Gavin Newsom and the California Natural Resources Agency. The Sea’s continu

Improving air quality and creating habitat at the Salton Sea are key priorities for Governor Gavin Newsom and the California Natural Resources Agency. The Sea’s continuing decline in elevation and resulting exposure of lakebed negatively impact surrounding communities and reduce remaining habitat for fish and wildlife. The California Natural Resources Agency, the California Department of Water Resources, and the California Department of Fish and Wildlife (together, the State Team) are focused on implementing the Salton Sea Management Program’s (SSMP’s) 10-Year Plan to improve conditions by constructing 30,000 acres of habitat and dust suppression projects around the Sea.

2021 Emergency Drought Salinity Barrier Project Water Quality Certification

California State Water Resources Control Board (SWRCB) | May 28th, 2021

The California Department of Water Resources (DWR) is proposing to implement the 2021 Emergency Drought Salinity Barrier Project (Project). The Project consists of instal

The California Department of Water Resources (DWR) is proposing to implement the 2021 Emergency Drought Salinity Barrier Project (Project). The Project consists of installation of a temporary emergency drought salinity barrier across West False River in the Sacramento-San Joaquin Delta (Delta). The barrier will be constructed of embankment rock (riprap). The purpose of the Project is to control saltwater intrusion into the Central and south Delta and conserve water in upstream reservoirs for other uses. Pursuant to Clean Water Act section 401, the State Water Resources Control Board (State Water Board) has authority to consider whether a proposed activity involving a discharge to navigable waters complies with applicable water quality standards and other appropriate requirements of state law and to issue a water quality certification if those requirements will be met. The State Water Board concludes that, as conditioned herein, water quality certification may be issued.  During drought conditions, the release of water stored in upstream reservoirs may be insufficient to repel salinity moving upstream from San Francisco Bay. According to DWR’s analyses, without the protection of the drought salinity barrier, saltwater intrusions could render Delta water unusable for agricultural needs, reduce habitat value for aquatic species, and affect roughly 25 million Californians who rely on the export of this water for personal use. Installation of the temporary rock barrier at West False River would limit salinity intrusion into the Central and south Delta and would potentially conserve water for a variety of uses system-wide.  On May 10, 2021, California Governor Gavin Newsom issued a Proclamation of State of Emergency (May 2021 Proclamation) due to drought conditions and directed DWR, among other things, to implement plans that address potential Delta salinity issues, including installation and removal of emergency drought salinity barriers as needed. The May 2021 Proclamation mandates that such emergency barriers be designed to conserve water for use later in the year to meet state and federal Endangered Species Act requirements, preserve to the extent possible water quality in the Delta, and retain water supply for human health and safety uses. The State Water Board and the California Department of Fish and Wildlife (CDFW) are also directed to immediately consider any necessary regulatory approvals needed to install emergency drought salinity barriers. Additionally, the May 2021 Proclamation suspends Water Code section 13247, which requires state agencies to comply with water quality control plans approved by the State Water Board, and suspends the California Environmental Quality Act (CEQA) for purpose of implementing actions such as the Project.  Installation and removal of the Project will require a permit from the United States Army Corps of Engineers (USACE) pursuant to Section 404 of the Clean Water Act. DWR is seeking emergency authorization under USACE’s Regional General Permit (RGP) 8 – Emergency Repair and Protection Activities. 

A global dataset of surface water and groundwater salinity measurements from 1980–2019

Scientific Data | July 13th, 2020

Salinization of freshwater resources is a growing water quality challenge, which may negatively impact both sectoral water-use and food security, as well as bio

Salinization of freshwater resources is a growing water quality challenge, which may negatively impact both sectoral water-use and food security, as well as biodiversity and ecosystem services. Although monitoring of salinity is relatively common compared to many other water quality parameters, no compilation and harmonisation of available datasets for both surface and groundwater components have been made yet at the global scale. Here, we present a new global salinity database, compiled from electrical conductivity (EC) monitoring data of both surface water (rivers, lakes/reservoirs) and groundwater locations over the period 1980–2019. The data were assembled from a range of sources, including local to global salinity databases, governmental organizations, river basin management commissions and water development boards. Our resulting database comprises more than 16.3 million measurements from 45,103 surface water locations and 208,550 groundwater locations around the world. This database could provide new opportunities for meta-analyses of salinity levels of water resources, as well as for addressing data and model-driven questions related to historic and future salinization patterns and impacts.

A multi-isotope (B, Sr, O, H, and C) and age dating (3H–3He and14C) study of groundwater from Salinas Valley, California: Hydrochemistry, dynamics, and contamination processes

American Geophysical Union (AGU) | January 31st, 2002

The chemical and isotope (11B/10B, 87Sr/86Sr, 18O/16O, 2H/H, 13C/12C, 14C, and 3He/3H) compositions of groundwater from the upper aquifer system of the Salinas Valley in

The chemical and isotope (11B/10B, 87Sr/86Sr, 18O/16O, 2H/H, 13C/12C, 14C, and 3He/3H) compositions of groundwater from the upper aquifer system of the Salinas Valley in coastal central California were investigated in order to delineate the origin and processes of groundwater contamination in this complex system. The Salinas Valley has a relatively deep, confined ‘‘400- foot’’ aquifer, overlain by a ‘‘180-foot’’ aquifer and a shallower perched aquifer, all made up of alluvial sand, gravel and clay deposits. Groundwater from the aquifers have different 14C ages: fossil (14C = 21.3 percent modern carbon (pmc) for the 400-foot aquifer and modern (14C = 72.2–98.2 pmc) for the 180-foot aquifer. Fresh groundwater in all aquifers is recharged naturally and artificially through the Salinas River. The two modes of recharge can be distinguished chemically.We identified several different saline components with distinguishable chemical and isotopic fingerprints. Saltwater intrusion in the northern basin has C1 concentrations up to 1700 mg/L, a Na/Cl ratio less than seawater, a marine Br/Cl ratio, a Ca/Cl ratio greater than seawater, d11B between +17 and +38% and 87Sr/86Sr between 0.7088 and 0.7096. Excess dissolved Ca, relative to the expected concentration for simple dilution of seawater, correlates with 87Sr/86Sr ratios, suggesting base exchange reaction with clay materials. (2) Agriculture return flow is high inNO3 and SO4, with a 87Sr/86Sr = 0.7082,d11B = 19% and d13C between 23 and 17%. The 3H–3He ages (5–17 years) and 14C data suggest vertical infiltration rates of irrigation water of 3–10 m/yr. (3) Nonmarine saline water in the southern part of the valley has high total dissolved solids up to 3800 mg/L, high SO4, Na/Cl ratio >1, d11B between +24 and +30%, and 87Sr/86Sr = 0.70852. This groundwater may have acquired its geochemical signature from leaching of sedimentary rocks associated with the Coast Range marine deposits of Mesozoic to early Cenozoic age. The combination of different geochemical and isotopic fingerprints enables us to delineate the impact of salt sources in different areas of the valley and to reconstruct the origin of the SO4-enriched NO3-depleted saline plume that is located west of the city of Salinas. We suggest that the latter is derived from a mixture of different natural saline waters rather than from anthropogenic contamination.

A Rapid Assessment Method to Identify Potential Groundwater Flooding Hotspots as Sea Levels Rise in Coastal Cities

Water, Multidisciplinary Digital Publishing Institute (MDPI) | October 25th, 2019

Sea level rise (SLR) will cause shallow unconfined coastal aquifers to rise. Rising groundwater can emerge as surface flooding and impact buried infrastructure, soil beh

Sea level rise (SLR) will cause shallow unconfined coastal aquifers to rise. Rising groundwater can emerge as surface flooding and impact buried infrastructure, soil behavior, human health, and nearshore ecosystems. Higher groundwater can also reduce infiltration rates for stormwater, adding to surface flooding problems. Levees and seawalls may not prevent these impacts. Pumping may accelerate land subsidence rates, thereby exacerbating flooding problems associated with SLR. Public agencies at all jurisdiction levels will need information regarding where groundwater impacts are likely to occur for development and infrastructure planning, as extreme precipitation events combine with SLR to drive more frequent flooding. We used empirical depth-to-water data and a digital elevation model of the San Francisco Bay Area to construct an interpolated surface of estimated minimum depth-to-water for 489 square kilometers along the San Francisco Bay shoreline. This rapid assessment approach identified key locations where more rigorous data collection and dynamic modeling is needed to identify risks and prevent impacts to health, buildings, and infrastructure, and develop adaptation strategies for SLR.

A Salton Sea Chronology (Prehistory-2015)

U.S. Bureau of Reclamation (USBR) | January 14th, 2016

A Water Resources Data Network Evaluation for Monterey County, California; Phase 1; South County

U..S. Geological Survey (USGS), Monterey County Flood Control and Water Conservation District | July 12th, 1986

An evaluation made of rainfall, surface water, groundwater, and water quality monitoring networks in Salinas River basin in southern Monterey County, California, proposed

An evaluation made of rainfall, surface water, groundwater, and water quality monitoring networks in Salinas River basin in southern Monterey County, California, proposed all long-term rain gages be continued for extending short-term records and suggested the installation of two additional recording gages. Eight new storage rain gages were suggested at midaltitudes of east and west sides of Salinas Valley where few data are available. The evaluation revealed some short-term gaging stations could be discontinued because of good regression relations between them and the long-term stations Arroyo Seco near Soledad. Of 16 stations selected for the proposed network, 4 are new recording stations, 6 are new nonrecording streamflow and water quality sampling sites, 5 are existing stations, and the last is a station operated from 1969 to 1976; also included are water quality sampling stations on Lakes Nacimiento and San Antonio. The proposed groundwater network was developed from information on geology, geohydrology, and groundwater quality, high priority objectives for groundwater network, and consideration for providing good areal coverage of levels and water quality. Of 145 sites selected, 86 are existing monitoring wells.

A Water Resources Data Network Evaluation for Monterey County, California; Phase 3, Northern Salinas River Drainage Basin

U.S. Geological Survey, Monterey County Flood Control and Water Conservation District | December 13th, 1990

Continuing data collection and analysis are vital to efficient development and management of water resources. To insure that water managers have adequate information on c

Continuing data collection and analysis are vital to efficient development and management of water resources. To insure that water managers have adequate information on conditions and trends, data-collection programs must be evaluated and updated periodically. Changes in population, land use, and agricultural practices may increase the demand for water, so that effective water management and supporting data collection become even more critical. Consideration of cost effectiveness, however, means that every site must count, and redundancy must be minimized. Water resources management and monitoring are ever-changing, and periodic reevaluation is a necessary part of this process. This report presents an evaluation of precipitation, surface-water, and ground-water monitoring networks in the northern Salinas River drainage basin of Monterey County, California. This report is third in a series of reports prepared in cooperation with the Monterey County Flood Control and Water Conservation District (MCFCWCD). The phase 1 report (Showalter and Hoffard, 1986) covers the southern Salinas River drainage basin, the phase 2 report covers the north county and coastal areas of Monterey County (W.E. Templin, P.E. Smith, and R.C. Schluter, U.S. Geological Survey, written commun., 1989), and this report (phase 3) covers the northern Salinas River drainage basin.

A Water Resources Data-Network Evaluation for Monterey County, California, Phase 3: Northern Salinas River Drainage Basin

U.S. Geological Survey, Monterey County Flood Control and Water Conservation District | December 15th, 1990

This report presents an evaluation of water resources data collection networks in the northern Salinas River drainage basin, Monterey County, California. The eval

This report presents an evaluation of water resources data collection networks in the northern Salinas River drainage basin, Monterey County, California. The evaluation, done in cooperation with the Monterey County Flood Control and Water Conservation District, covers both quantity and quality monitoring by precipitation, surface-water, and ground-water networks. The report describes existing networks in the study area and possible additional data collection. The study identified 34 precipitation gages in the study area, of which 20 are active. The stations are concentrated in the northwestern part of the study area. Data are lacking for the eastern and southern parts of the study area, as well as the southwestern slopes of the Gabilan Range. No precipitation-quality networks were identified. Possible data-collection efforts for precipitation quality include monitoring for acid rain and for pesticides in precipitation. The study identified 10 streamflow-gaging stations, of which 6 are active. To meet the objectives for streamflow networks that are outlined in the report, all sites could be reactivated, and two of the inactive sites could be relocated to improve the reliability of the data. Besides these stations, nine possible additional streamflow-gaging sites were identified. The Monterey County Flood Control and Water Conservation District samples one surface-water site for suspended sediment, specific conductance, and chlorides. Several agencies have done water-quality sampling in the past, but only five sites are active. Reactivation of the 45 inactive sites might help to meet the various surface-water-quality objectives described in the report. Development of a stream-reach rating system also could help to identify parts of the study area most in need of sampling. The Monterey County Flood Control and Water Conservation District maintains three networks to measure ground-water levels on a monthly basis, during peak irrigation, and at the end of the irrigation season. The District measures water levels in 318 wells. The only other network identified for this report was operated by the U.S. Geological Survey, and none of its five wells are active. The study identified 128 sections in which no ground-water-level monitoring is presently done. Well coverage is densest in the saltwater-intrusion areas near Castroville, California. Wells in the rest of the study area are more sparsely distributed and are concentrated down the center of the drainage basin in the alluvial ground-water basin. The ideal initial baseline network of ground-water-quality wells would be an evenly spaced grid of index wells within each aquifer, with a density of one per section. Once baseline conditions were established, representative wells could be selected and monitored annually. As of 1985, the Monterey County Flood Control and Water Conservation District monitored 379 study wells in the area for various water-quality conditions. Other networks monitor (or propose the monitoring of) 135 wells. The District collects samples in summer months to monitor saltwater intrusion near Castroville. Annual samples also are analyzed for chloride, specific conductance, and nitrate. Every 5 years, the District does a complete mineral analysis on each study well. Improvements in network coverage are suggested to better approximate ideal network coverage. The adequacy of wells in existing monitoring networks for representing actual conditions in the ground-water basins was not established conclusively. Possible redundancy of information from existing networks was not evaluated statistically. Despite these limitations, this report does provide a basis for assessing the adequacy of ground-water-level networks in the study area. The computerized Geographic Information System (GIS) that is planned for Monterey County could easily use the information in this report for the needed initial analysis of network adequacy. The feasibility of management and analysis of large complicated data bases (such as the ground water networks identified in this report) is substantially improved through the use of state-of-the-art GIS tools now available.