North Coast

Interim instream flow criteria for the protection of fishery resources in the Scott River watershed, Siskiyou County

California Department of Fish and Wildlife (CDFW) | February 6th, 2017

This document describes the methods and results of an analysis using historical flow data and regional regression relationships to develop interim instream flow criteria

This document describes the methods and results of an analysis using historical flow data and regional regression relationships to develop interim instream flow criteria suitable for anadromous fish in the Scott River watershed in Siskiyou County. The Scott River watershed provides aquatic habitat for four species of anadromous fish; Chinook Salmon (Oncorhynchus tshawytscha), Coho Salmon (O. kisutch), steelhead trout (O. mykiss), and Pacific Lamprey (Lampetra tridentata). Specifically, the Scott River is one of the most important Coho Salmon spawning and rearing tributaries in the Klamath River watershed. Instream flow requirements can be generated from flow standard setting techniques or from the results of site specific studies. The interim instream flow criteria presented for the Scott River were developed using flow standard setting techniques. Stream flow standards derived from standard setting techniques are designed to identify the environmental resource in need of flow protection, identify biologically significant criterion that can be used to measure potential flow related impacts, and specify the amount of flow required to protect the resource. Most individual standards evaluate only one or more, but not all the criterion needed to fully evaluate the flow needs of an aquatic species. This limitation can lead to prescribing a single minimum threshold or “flat-line” affect (Poff et al. 1997). The seasonal and inter-annual variability in the hydrograph must be maintained to protect stream ecology and provide an ecosystem based standard (Annear 2004). To account for the seasonal and the inter-annual hydrologic variability of the Scott River, the Department applied a detailed hydrologic analysis along with application of three standard setting methods to evaluate the life history flow needs of salmonids in the Scott River near Fort Jones. Adult fish passage was estimated using the equation developed by R2 Resources (R2 2008) for the State Water Resources Control Board’s (SWRCB) North Coast Instream Flow Policy (SWRCB 2014), spawning and juvenile rearing were evaluated using the Hatfield and Bruce regional equations (Hatfield and Bruce 2000), and the results were adjusted monthly based on estimates of unimpaired hydrology using Tessmann’s adaptation (Tessmann 1980) of the Tennant or Montana Method (Tennant 1975).

Introducing Time-Limited Permits to California’s Riparianism

University of California, Davis (UC Davis) | December 1st, 2023

Investigating the Link Between Surface Water and Groundwater in the Tule Lake Subbasin, Oregon and California

Portland State University | August 13th, 2014

Water allocation in the upper Klamath Basin of Oregon and California has been challenging. Irrigators have increasingly turned to groundwater to make up for surf

Water allocation in the upper Klamath Basin of Oregon and California has been challenging. Irrigators have increasingly turned to groundwater to make up for surface water shortages because of shifts in allocation toward in-stream flows for Endangered Species Act-listed fishes. The largest increase in groundwater pumping has been in and around the Bureau of Reclamation’s Klamath Irrigation Project, which includes the Tule Lake subbasin in the southern part of the upper Klamath Basin. Previous groundwater flow model simulations indicate that water level declines from pumping may result in decreased flow to agricultural drains in the Tule Lake subbasin. Agricultural drains on the Klamath Project are an important source of water for downstream irrigators and for the Tule Lake and Lower Klamath Lake National Wildlife Refuges. To better assess the impact of increased pumping on drain flow and on the water balance of the groundwater system, flow data from agricultural drains were evaluated to investigate the changes that have taken place in groundwater discharge to drains since pumping volumes increased. Additionally, a fine-grid groundwater model of the Tule Lake subbasin was developed based on the existing regional flow model. The fine-grid model has sufficient vertical and horizontal resolution to simulate vertical head gradients, takes advantage of time-series data from 38 observation wells for model calibration, and allows agricultural drains to be more explicitly represented. Results of the drain flow analysis show that the groundwater discharge to agricultural drains has decreased by approximately 4000 hectare-meters from the 1997-2000 average discharge. Most of this decrease takes place in the northern and southeastern portions of the subbasin.  Results of the groundwater model show that the initial source of water to wells is groundwater storage. By 2006, approximately 56% of the water from wells is sourced from agricultural drains.

Investigation on the Feasibility of Developing Uniformwater Recycling Criteria ror Direct Potable Reuse

California State Water Resources Control Board (SWRCB) | December 1st, 2016

The population of California is projected to increase from 38 million to 50 million by the year 2049. This population increase will have a dramatic impact on the water ne

The population of California is projected to increase from 38 million to 50 million by the year 2049. This population increase will have a dramatic impact on the water needs of the State. To address this increased water need, the State will take a variety of actions as outlined in the Governor’s California Water Action Plan, first released in 2014 and recently updated in 2016 (CA Natural Resources Agency, 2016). One component of that plan is to increase the use of recycled water. The State Water Board has set a mandate of increasing the use of recycled water by 200,000 acre-foot per year (AFY) by 2020 and an additional 300,000 AFY by 2030. Although the use of recycled water for non-potable uses such as agricultural and landscape irrigation is already well established and has been regulated for decades in California, increasing the use of recycled water for both non-potable uses as well as a source of potable water (“potable reuse”) is important for the State to be able to meet this mandate. For example, groundwater replenishment (groundwater recharge), which is an indirect form of potable reuse, has the capacity to reuse 200,000 acre-feet of recycled water a year via just eight projects throughout California. Accordingly, the State Water Board revised and adopted uniform water recycling criteria for groundwater replenishment in 2014 and is in the process of establishing uniform water recycling criteria for the augmentation of surface water reservoirs used as a source of drinking water supply, which is another form of indirect potable reuse.

Irrigation Water Use in the Central Valley of California

California Department of Water Resources (DWR) | January 1st, 1985

Jet stream dynamics, hydroclimate, and fire in California from 1600 CE to present

National Academy of Sciences (NAS) | March 4th, 2019

Moisture delivery in California is largely regulated by the strength and position of the North Pacific jet stream (NPJ), winter high-altitude winds that influence regiona

Moisture delivery in California is largely regulated by the strength and position of the North Pacific jet stream (NPJ), winter high-altitude winds that influence regional hydroclimate and forest fire during the following warm season. We use climate model simulations and paleoclimate data to reconstruct winter NPJ characteristics back to 1571 CE to identify the influence of NPJ behavior on moisture and forest fire extremes in California before and during the more recent period of fire suppression. Maximum zonal NPJ velocity is lower and northward shifted and has a larger latitudinal spread during presuppression dry and high-fire extremes. Conversely, maximum zonal NPJ is higher and southward shifted, with narrower latitudinal spread during wet and low-fire extremes. These NPJ, precipitation, and fire associations hold across pre–20th-century socioecological fire regimes, including Native American burning, postcontact disruption and native population decline, and intensification of forest use during the later 19th century. Precipitation extremes and NPJ behavior remain linked in the 20th and 21st centuries, but fire extremes become uncoupled due to fire suppression after 1900. Simulated future conditions in California include more wet-season moisture as rain (and less as snow), a longer fire season, and higher temperatures, leading to drier fire-season conditions independent of 21st-century precipitation changes. Assuming continuation of current fire management practices, thermodynamic warming is expected to override the dynamical influence of the NPJ on climate–fire relationships controlling fire extremes in California. Recent widespread fires in California in association with wet extremes may be early evidence of this change.

Juvenile salmonids traverse coastal meta-nurseries that connect rivers via the sea

Ecological Society of America (ESA) | April 30th, 2025

Conventionally, juvenile salmonids are thought to migrate unidirectionally from freshwater systems to marine systems and therefore only inhabit natal drainages. Although

Conventionally, juvenile salmonids are thought to migrate unidirectionally from freshwater systems to marine systems and therefore only inhabit natal drainages. Although scattered evidence suggests juveniles can move bidirectionally between freshwater rivers and the ocean, including into non-natal drainages, such movements have never been documented with high replication. Here, we detected hundreds of movements of juvenile salmonids between drainages that involved 0–22% of cohort emigrants in Washington State and California. Individuals moved up to nine times and between drainages up to 70 km apart. These findings reveal a life-history type of salmonids whose remarkably complex migrations have gone unnoticed. Implicitly, juveniles may use any coastal freshwater habitat accessible from the sea and may not descend from spawning populations of drainages they inhabit. Consequently, typical conservation focused on natal drainages may overlook freshwater habitat elsewhere. A concept of coastal areas as meta-nurseries formed by multiple watersheds connected by the sea may accurately describe anadromous species’ habitat options and better inform management.

Klamath Basin Settlement Agreements

Congressional Research Service (CRS) | October 21st, 2015

The Klamath River Basin on the California-Oregon border is a focal point for local and national discussions on water allocation and species protection. Previously, water

The Klamath River Basin on the California-Oregon border is a focal point for local and national discussions on water allocation and species protection. Previously, water and species management issues have exacerbated competition and generated conflict among several interests—farmers; Indian tribes; commercial and sport fishermen; federal water project and wildlife refuge managers; environmental groups; hydropower facility operators; and state, local, and tribal governments. Drought conditions and a call for water by senior water rights holders in 2013 have again brought these issues to the forefront. In 2010, the Secretary of the Interior and the governors of Oregon and California, along with multiple interest groups, announced the results of a multiyear negotiation process to resolve long-standing issues in the basin: two interrelated agreements, supported by the federal government and signed by the two states and numerous other parties. These agreements, known as the Klamath Basin Restoration Agreement (KBRA) and the Klamath Hydroelectric Settlement Agreement (KHSA), together aim to provide for water deliveries to irrigators and wildlife refuges, fish habitat restoration, and numerous other related actions. Generally, the KBRA provides for actions intended to restore Klamath fisheries and for assurances for water deliveries to wildlife refuges and federal project irrigators under certain circumstances, among other things. The KHSA lays out a process that could lead to the removal of four privately owned dams on the Klamath River. This dam removal would be one of the largest and most complex projects of its kind ever undertaken. Some parts of the Klamath agreements are being carried out under existing authorities. Studies to inform a determination on dam removal under the KHSA by the Secretary of the Interior are complete, and some restoration actions have been initiated. However, congressional authorization is required for the most significant components of the agreements to be implemented. The KBRA and KHSA did not address all outstanding issues in the basin. A water rights adjudication by the state of Oregon (in progress since the 1970s) is ongoing. In 2013, the adjudication reaffirmed “time immemorial” tribal water rights in the upper part of the Klamath Basin, confirming that tribal water rights are senior to those of other water rights holders. This resulted in a “call” on water rights (i.e., notice by senior water rights holders that their demands exceed available flows), and led to reductions to water supplies for some junior users during the low water year of 2013. To resolve these issues and prevent such a scenario from occurring again, a separate settlement agreement (the Upper Klamath Basin Settlement Agreement) was negotiated by stakeholders and finalized in April 2014. To be implemented, the agreement would need to be authorized along with the KBRA and KHSA. The KBRA and KHSA were originally set to expire in 2012 if no authorizing legislation was enacted, but they have since been extended (most recently through 2015). Parties may also withdraw individually from the agreements, and several parties initiated this process of withdrawal. In the 114th Congress, S. 133 would authorize the Klamath agreements, including a suite of new federal actions that have received support from disparate parties and are required for the agreements to be implemented. Previous legislation in the 113th Congress (S. 2379) was ordered to be reported out of the Senate Committee on Energy and Natural Resources on November 13, 2014.

Klamath River Basin Issues: An Overview of Water Use Conflicts

Congressional Research Service (CRS) | June 13th, 2002

Severe drought in 2001 affected the Klamath River Basin, an area on the California-Oregon border, exacerbating competition for scarce water resources and generating confl

Severe drought in 2001 affected the Klamath River Basin, an area on the California-Oregon border, exacerbating competition for scarce water resources and generating conflict among several interests – farmers, municipal and industrial users, commercial and sport fishermen, other recreationists, federal wildlife refuges, environmental groups, and Indian Tribes. The conflicts over water distribution and allocation are physically and legally complex, reflecting the varied and sometimes competing uses of limited water supplies in the Upper Basin. On April 6, 2001, the Bureau of Reclamation (Bureau), which has supplied water to farms in the Upper Basin for nearly 100 years, announced that “no water [would] be available” for farms normally receiving water from the Upper Klamath Lake, so that scarce water could be used to protect species listed as endangered or threatened under the Endangered Species Act (ESA). Water was available to some farmers from other sources (e.g., wells and other Bureau sources); however, many farmers were not able to plant or harvest crops due to severe cutbacks in water supplies. Emotions ran high on all sides of the issues, and the water control gates were unlawfully opened by protesters. Although the Basin has received significantly more precipitation in 2002, many issues remain in dispute. In addition, several judicial decisions have affected the issues with respect to the listed species as well as tribal rights. On May 31, 2002, the U.S. Fish and Wildlife Service and the National Marine Fisheries Service both issued Final Biological Opinions on the Bureau’s 10-year Operation Plan for the Klamath Project. The agencies found that the Bureau’s proposed action is likely to jeopardize the continued existence of the two listed suckers and coho salmon, as well as result in the adverse modification of proposed critical habitat; however, both Opinions also included “reasonable and prudent alternatives” for operating the Project that would remove the jeopardizing effects of the proposed action. However, on June 3, 2002, the Bureau formally rejected both Final Biological Opinions, but opted instead to operate under a one-year plan that it asserts complies with the Opinions. Independently, in March 2002, the President appointed a high-level working group to develop solutions. Congress has responded to the controversy in a number of ways, including holding several oversight hearings and appropriating funds for water conservation activities in the area. This report provides background on the geographic, historic, and legal underpinnings of the current conflicts. Because the report focuses on the current conflicts, it deals primarily with Klamath Project operations in the Upper Klamath Basin and effects associated with water releases from Upper Klamath Lake.

Klamath/San Joaquin/Sacramento Hydroclimatic Reconstructions from Tree Rings

California Department of Water Resources (DWR) | February 7th, 2014

This is a draft final report for Agreement Number 4600008850, “Klamath/San Joaquin/Sacramento Hydroclimatic Reconstructions”, signed October 13, 2010.  Work includes

This is a draft final report for Agreement Number 4600008850, “Klamath/San Joaquin/Sacramento Hydroclimatic Reconstructions”, signed October 13, 2010.  Work includes developing new and updated tree-ring chronologies, reconstructing specified streamflow and/or precipitation records in the Klamath, San Joaquin and Sacramento River Basins, and analyzing the time series properties of the reconstructions. These reconstructions allow assessment of hydrologic variability over centuries to millennia and give context for assessing recent drought events. Tasks on this project included field collections; laboratory work in sample preparation, dating and measurement; and statistical work in chronology development, reconstruction, and analysis of those reconstructions. The interpretation of the reconstructions includes five main components : 1) place instrumental-period flow statistics in a long-term context, 2) quantify droughts and wet periods, 3) identify cycles in wetness and dryness, 4) check consistency with other paleoclimatic data, and 5) assess reconstructed flow variations in the context of expected scenarios of climate. A total of 16 different hydroclimatic series – 11 flow records and 5 precipitation records, were reconstructed. This report summarizes the research project products and results. The Data and Methods section of this report describes the field collections and development of tree-ring chronologies, reconstruction modeling, and methods of analyzing reconstructions. The Results section focuses on the interpretation of selected key reconstructions for the Klamath, Sacramento, and San Joaquin basins. Annual time series of the 16 reconstructions are included as products in an appendix and in a digital spreadsheet.