Sacramento River

Best Management Practices of the Sustainable Management of Groundwater Land Subsidence

California Department of Water Resources (DWR) | January 21st, 2026

The Subsidence Best Management Practices document (Subsidence BMP) provides a guide on the fundamentals of land surface subsidence (also called “land subsidence” or �

The Subsidence Best Management Practices document (Subsidence BMP) provides a guide on the fundamentals of land surface subsidence (also called “land subsidence” or “subsidence”), technical assistance related to subsidence, and best practices for managing subsidence. The Subsidence BMP also provides specific information about subsidence in California and how it must be considered within the structure of the Sustainable Groundwater Management Act (SGMA). Subsidence is one of the six sustainability indicators required to be managed under SGMA. The Subsidence BMP does not supersede or replace any existing local, state, or federal regulations. Rather, it is meant to help groundwater managers, especially Groundwater Sustainability Agencies and the public, better understand land subsidence and how it can be managed.

Best Management Practices of the Sustainable Management of Groundwater: Land Subsidence (Draft)

California Department of Water Resources (DWR) | July 23rd, 2025

For almost a century, parts of California have been gradually sinking, impacting critical infrastructure and the communities who rely on it. Recognizing this challenge, t

For almost a century, parts of California have been gradually sinking, impacting critical infrastructure and the communities who rely on it. Recognizing this challenge, the Department of Water Resources has released a draft Best Management Practices document for public comment that will help local water agencies address this growing concern and support groundwater reliant communities. Click here for the full DWR press release.

Biennial Report of the Fish and Game Commission of California 1924-26

California Fish and Game Commission | June 30th, 1926

Bifenthrin, a ubiquitous contaminant, impairs the development and behavior of the threatened Longfin Smelt during early life stages

American Chemical Society (ACS) | June 23rd, 2023

The Longfin Smelt (Spirinchus thaleichthys) population in the San Franscisco Bay/Sacramento-San Joaquin Delta (Bay-Delta) has declined to ∼1% of its pre-1980s abundance

The Longfin Smelt (Spirinchus thaleichthys) population in the San Franscisco Bay/Sacramento-San Joaquin Delta (Bay-Delta) has declined to ∼1% of its pre-1980s abundance and, as a result, is listed as threatened under the California Endangered Species Act. The reasons for this decline are multiple and complex, including the impacts of contaminants. Because the spawning and rearing seasons of Longfin Smelt coincide with the rainy season, during which concentrations of contaminants increase due to runoff, we hypothesized that early life stages may be particularly affected by those contaminants. Bifenthrin, a pyrethroid insecticide commonly used in agricultural and urban sectors, is of concern. Concentrations measured in the Bay-Delta have been shown to disrupt the behavior, development, and endocrine system of other fish species. The objective of the present work was to assess the impact of bifenthrin on the early developmental stages of Longfin Smelt. For this, embryos were exposed to 2, 10, 100, and 500 ng/L bifenthrin from fertilization to hatch, and larvae were exposed to 2, 10, and 100 ng/L bifenthrin from one day before to 3 days post-hatch. We assessed effects on size at hatch, yolk sac volume, locomotory behavior, and upper thermal susceptibility (via cardiac endpoints). Exposure to these environmentally relevant concentrations of bifenthrin did not significantly affect the cardiac function of larval Longfin Smelt; however, exposures altered their behavior and resulted in smaller hatchlings with reduced yolk sac volumes. This study shows that bifenthrin affects the fitness-determinant traits of Longfin Smelt early life stages and could contribute to the observed population decline.

Big Valley Groundwater Sustainability Plan

Lassen and Modoc Counties Groundwater Sustainability Agencies | December 8th, 2021

The Big Valley Groundwater Basin (BVGB, Basin, or Big Valley) lies on the border of Modoc and Lassen counties in one of the most remote and untouched areas of California.

The Big Valley Groundwater Basin (BVGB, Basin, or Big Valley) lies on the border of Modoc and Lassen counties in one of the most remote and untouched areas of California. The sparsely populated Big Valley has a rich biodiversity of wildlife and native species who live, feed and raise young on the irrigated lands throughout the Basin. The snow-fed high desert streams entering the Basin have seasonal hydrographs with natural periods of reduced flows or complete cessation of flows late in the summer season. The Pit River is the largest stream and is so named because of the practice, employed by the Achumawi and other Native American bands that are now part of the Pit River Tribe, of digging pits in the river channel when it went dry to expose water and trap game that came to water at the river. Farming and ranching in Big Valley date back to the late 19th and early 20th centuries, when families immigrated to Big Valley and made use of the existing water resources. A large amount of the land in the Basin is still owned and farmed by the families who homesteaded here. Historically, agriculture was complemented by a robust timber industry as a key component of the economy for Big Valley, which supported four lumber mills. Due to regulations and policies imposed by state and federal governments, the timber industry has been diminished over time and subsequently caused a great economic hardship to the Big Valley communities. Stakeholders realize that the Sustainable Groundwater Management Act of 2014 (SGMA) will unfortunately cause a similar decline to agriculture. The change in land management has transformed once thriving communities in the Basin to “disadvantaged” and “severely disadvantaged” communities. Viable agriculture is of paramount importance to the residents of Big Valley because it supports the local economy and unique character of the community. As required by SGMA, stakeholders have developed a sustainability goal: The sustainability goal for the Big Valley Groundwater Basin is to maintain a locally governed, economically feasible, sustainable groundwater basin and surrounding watershed for existing and future legal beneficial uses with a concentration on agriculture. Sustainable management will be conducted in context with the unique culture of the basin, character of the community, quality of life of the Big Valley residents, and the vested right of agricultural pursuits through the continued use of groundwater and surface water. Lassen and Modoc counties are fulfilling their unfunded, mandated roles as Groundwater Sustainability Agencies (GSAs) to develop this Groundwater Sustainability Plan (GSP) after exhausting its administrative challenges to the California Department of Water Resources’ (DWR’s) determination that Big Valley qualifies as a medium-priority basin. Both counties are disadvantaged, have declining populations, and have no ability to cover the costs of GSP development and implementation.

Biological opinion and conference opinion on the long-term operations of the Central Valley Project and State Water Project

National Marine Fisheries Service (NMFS) | June 4th, 2009

Biological opinion for the California Water Fix (National Marine Fisheries Service)

National Marine Fisheries Service (NMFS) | June 16th, 2017

Based on the best available scientific and commercial information, the Biological Opinion (Opinion) concludes that the Project is not likely to jeopardize the continued e

Based on the best available scientific and commercial information, the Biological Opinion (Opinion) concludes that the Project is not likely to jeopardize the continued existence of federally listed: • Endangered Sacramento River winter-run Chinook salmon (Oncorhynchus tshawytscha), • Threatened Central Valley spring-run Chinook salmon (0. tshawytscha), • Threatened Central Valley steelhead ( 0. my kiss), • Threatened Southern Distinct Population Segment (DPS) of North American green sturgeon (Acipenser medirostris), and • Endangered Southern Resident killer whales ( Orcinus area). NMFS concludes that the Project is not likely to destroy or adversely modify the designated critical habitats of: • Sacramento River winter-run Chinook salmon, • Central Valley spring-run Chinook salmon, • Central Valley steelhead, and • Southern DPS of North American green sturgeon. Southern Resident killer whales critical habitat is outside of the action area. As required by section 7 of the ESA, for the above species, NMFS has included an incidental take statement for activities within the proposed Project that do not require further analysis. The incidental take statement describes reasonable and prudent measures NMFS considers necessary or appropriate to minimize the impact of incidental take associated with these activities. The take statement also sets forth nondiscretionary terms and conditions, including monitoring and reporting requirements, that the U.S. Bureau of Reclamation (Reclamation) as the Federal action agency, must comply with to carry out the reasonable and prudent measures. Incidental take from activities that meet these terms and conditions will be exempt from the ESA’s prohibition against the take of listed species. The Project for this consultation is a “mixed programmatic action” because it approves some actions that are not subject to further section 7 consultation as well as provides programmatic review of future actions that would be authorized, at a later time. For actions that are expected to be developed in the future (mitigation/restoration, monitoring, adaptive management), take of listed species would not occur until those future actions were authorized. For other actions (construction and operations), NMFS is providing an incidental take statement with this Opinion. The enclosed Opinion is based on information provided in the Reclamation’s transmittal letter and biological assessment, correspondence and discussions between NMFS, Reclamation, and California Department of Water Resources staff, and consultants; a final proposed action issued on June 2, 2017; comments received from Reclamation; peer review reports from the Delta Stewardship Council’s Delta Science Program; and an extensive literature review completed by NMFS staff. A complete administrative record of this consultation is on file at the NMFS California Central Valley Office. NMFS also concurs with Reclamation’s conclusion that the proposed action is not likely to adversely affect threatened Central California Coast steelhead (O. mykiss), endangered Central California Coast coho salmon (O. kisutch), or the designated critical habitat for Central California Coast steelhead. Designated critical habitat for Central California Coast coho salmon is not included in the action area. NMFS reviewed the likely effects of the proposed action on essential fish habitat (EFH), pursuant to section 305(b) of the Magnuson-Stevens Fishery Conservation and Management Act (MSA) (16 U.S.C. 1855(b)), and concluded that the Project would adversely affect the EFH of Pacific Coast salmon, Coastal Pelagic species, and Pacific Coast Groundfish in the action area. We have included these EFH consultation results in Section 3 of this document. The EFH consultation itself includes Conservation Recommendations specific to the adverse effects to EFH identified during our review. Reclamation has a statutory requirement under section 305(b)(4)(B) of the MSA to submit a detailed written response to NMFS within 30 days of receipt of these EFH conservation recommendations, and 10 days in advance of any final approval of the action if the response is inconsistent with any of NMFS’ EFH Conservation Recommendations. The written response must include a description of measures adopted by Reclamation for avoiding, minimizing, or mitigating the impact of the Project on EFH (50 CFR § 600.920(k)). If unable to complete a final response within 30 days, Reclamation should provide an interim written response within 30 days before submitting its final response. In the case of a response that is inconsistent with our recommendations, Reclamation must explain its reasons for not following the recommendations, including the scientific justification for any disagreements with NMFS over the anticipated effects of the Project and the measures needed to avoid, minimize, or mitigate (also referred to by NMFS as measures that "offset") such effects.

Biological Opinion for the California Water Fix (US Fish and Wildlife Service)

U.S. Fish and Wildlife Service (FWS) | June 23rd, 2017

This consultation examines whether the California WaterFix (CWF) Proposed Action (PA) is likely to jeopardize the continued existence of the threatened California red-leg

This consultation examines whether the California WaterFix (CWF) Proposed Action (PA) is likely to jeopardize the continued existence of the threatened California red-legged frog (Rana draytonii), threatened California tiger salamander (Central California Distinct Population Segment; Ambystoma californiense), threatened delta smelt (Hypomesus transpacificus), threatened giant garter snake (Thamnophis gigas\ endangered Least bell's vireo (Vireo belliipusillus), endangered San Joaquin kit fox (Vulpes macrotis mutica), threatened valley elderberry longhorn beetle (Desmocerus californicus dimorphus), threatened vernal pool fairy shrimp (Branchinecta lynchi), endangered vernal pool tadpole shrimp (Lepidurus packardi), and threatened western yellow-billed cuckoo (Coccyzus americanus occidentalis). Additionally, this consultation addresses whether the CWF PA is likely to destroy or adversely modify delta smelt critical habitat. The attached Final BiOp incorporates relevant information provided by the action agencies and applicant, including comments, changes, and additions to the CWF provided since consultation was initiated. The Service has prepared a mixed programmatic BiOp on the CWF. This BiOp represents the culmination of consultation on a mix of standard-level and programmatic-level project elements. An analysis and conclusion of whether or not the entire CWF action is likely to jeopardize each listed species or destroy or adversely modify designated critical habitat is included in this BiOp. All activities addressed programmatically will be subject to a subsequent consultation on future Federal actions in order to proceed. The following activities analyzed as a standard consultation are: (1) construction of the tunnels; (2) expansions and other modifications of Clifton Court Forebay; (3) associated infrastructure; (4) geotechnical explorations, (5) compensatory mitigation associated with construction except the North Delta Diversions (NDD), Head of Old River Gate (HORG), and Contra Costa Water District (CCWD) settlement agreement facilities; and (6) specific construction-related conservation measures including preconstruction surveys for listed terrestrial species. Where incidental take of threatened or endangered species is reasonably certain to occur, an Incidental Take Statement for these activities is included with this BiOp. The following activities requiring future Federal approvals and therefore addressed programmatically are: (1) construction of the NDD and associated structures; (2) construction of the HORG; (3) construction of the CCWD settlement agreement facilities; (4) operations of new and existing CVP and SWP water facilities under dual conveyance; (5) future maintenance; (5) future monitoring; (6) compensatory mitigation associated with construction of the NDD, HORG, and CCWD settlement agreement facilities; and (7) the CWF Adaptive Management Program. In order to ensure that future actions developed for the CWF are consistent with this analysis, Reclamation and DWR have proposed a framework consisting of Guiding Principles that are analyzed as part of this BiOp. One or more subsequent consultations will be needed to address activities associated with future approvals. No Incidental Take Statement is included for activities addressed programmatically because those subsequent consultations will address incidental take associated with those activities. The Service has analyzed the operational scenario for CWF included in the BA. The agencies recognize this operational scenario will change between now and the time that the CWF facilities are operational. Changes to the operational scenario will be analyzed in subsequent consultation. The attached BiOp addresses effects of the CWF to 16 federally-listed species and designated critical habitat. Appendix A of the BiOp includes justifications for the species and critical habitat that were determined not likely to be adversely affected. Effects to the remainder of the species and critical habitat are addressed in the BiOp. The Service has determined that the CWF is not likely to jeopardize the continued existence of any of these species, and is not likely to destroy or adversely modify designated critical habitat.

Biological Opinion for the Reinitiation of Consultation on the Long-Term Operation of the Central Valley Project and State Water Project

National Marine Fisheries Service (NMFS) | December 6th, 2024

Biological Opinion on Long-term Operation of the Central Valley Project and the State Water Project

National Marine Fisheries Service (NMFS) | October 21st, 2019