To Quench a Thirst

San Diego County Water Authority (SDCWA) | October 10th, 2023

The story has three parts: the first tells how the early residents lived with their local resources; the second, which begins in the 1920s, tells the story of how the [Sa

The story has three parts: the first tells how the early residents lived with their local resources; the second, which begins in the 1920s, tells the story of how the [San Diego County] region has become heavily dependent on imported water, and the third is just starting. It is the part of the story about how the region will learn to thrive in a changing climate that has turned 20th century norms for water and weather upside down.

To Stop Desert Encroachment

Scientific American | November 1st, 1938

When Spanish vaqueros first entered the interior valley of California they saw only a vast expanse of desert, broken infrequently by patches of green vegetation a

When Spanish vaqueros first entered the interior valley of California they saw only a vast expanse of desert, broken infrequently by patches of green vegetation along the water courses. Little did they dream that in a span of two generations the region would become one of the world's garden spots, the home of thousands of prosperous families, and the source of millions of tons of food products known around the world. They did not envision the romance and adventure that marked the development of this great inland empire-now a two billion dollar agricultural wonderland built by irrigation and wholly dependent upon a single natural resource-water.

Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act

Stanford University | February 14th, 2019

In 2014, California enacted the Sustainable Groundwater Management Act (SGMA), which requires local agencies to develop and implement groundwater sustainability plans (G

In 2014, California enacted the Sustainable Groundwater Management Act (SGMA), which requires local agencies to develop and implement groundwater sustainability plans (GSPs) in all groundwater basins designated by the California Department of Water Resources (DWR) as high or medium priority by 2020 or 2022, depending on basin condition. For the first time in California’s history, agencies managing groundwater under SGMA must assess the impacts of groundwater pumping on water supply and surface water flows and avoid “significant and unreasonable adverse impacts on beneficial uses of the surface water.” SGMA’s legal and regulatory requirements pertaining to interconnected surface water – defined in SGMA as, “surface water that is hydraulically connected at any point by a continuous zone to the underlying aquifer and the overlying surface water is not completely depleted.” – represent a significant step forward in recognizing the interconnected nature of surface water and groundwater and for managing this resource accordingly. However, because groundwater-surface water connectivity was not a common management consideration prior to the enactment of SGMA, many basins lack data or models or technical capacity to adequately characterize interconnected surface water (ISW) and evaluate the impacts of groundwater pumping on these systems. Thus, meeting legal and regulatory requirements related to ISW may be hindered by a lack of information about both the location and timing of such waters, as well as the many beneficial uses and users that they support. In March 2018, Water in the West, The University of Victoria, Foundry Spatial, The Nature Conservancy (TNC) and Environmental Defense Fund co-hosted a workshop on tools to assess ISW under SGMA. The workshop, which included a small, select group of hydrologists, water managers, water lawyers, nongovernmental organizations (NGOs) and academia, focused on four main areas: 1) Accounting for beneficial uses and users in GSP development and implementation; 2) Identifying physical or analytical approaches for characterizing, quantifying and monitoring ISW; 3) Using hydrological modeling to assess the effects of groundwater pumping on ISW and streamflow depletions; and 4) Understanding the functionality and use of decision support tools from other jurisdictions This report summarizes key findings from the one-day workshop and a short questionnaire completed by workshop participants during the day. A list of workshop attendees, the workshop agenda and workshop questionnaire can be found in Appendices A-C, respectively.

Tools for managing hydrologic alteration on a regional scale II: Setting targets to protect stream health

Freshwater Biology (Wiley) | January 15th, 2018

1. Widespread hydrologic alteration creates a need for tools to assess ecological impacts to streams that can be applied across large geographic scales. A regional framew

1. Widespread hydrologic alteration creates a need for tools to assess ecological impacts to streams that can be applied across large geographic scales. A regional framework for biologically based flow management can help catchment managers prioritise streams for protection, evaluate impacts of disturbance or interventions and provide a starting point for causal assessment in degraded streams. However, lack of flow data limit the ability to assess hydrologic conditions across a region. 2. Hydrologic models can address this problem. Regionally calibrated hydrologic models were used to estimate current and reference flows at 572 bioassessment sites in southern and central coastal California. Flow alteration was characterised as the difference in 39 flow metrics calculated from simulations of present‐day and reference flow time‐series, calculated under up to four precipitation conditions. 3. Biological condition was assessed with the California Stream Condition Index (CSCI) and its components. Logistic regressions were used to predict the likelihood of high scores (i.e. ≥10th percentile of the CSCI reference calibration data). Statistically significant relationships between increasing severity of hydrologic alteration and decreasing biological condition were used to set thresholds that reflected tolerance for risk of a stakeholder advisory group. 4. An index of hydrologic alteration was created by selecting flow metrics based on their importance for predicting biological response variables in boosted regression tree models. Metrics were selected in the order of decreasing importance, and no more than two metrics per metric class were selected (i.e. duration, frequency, magnitude, timing and variability). Seven metrics were selected: HighDur (duration of high‐flow events), HighNum (# of high‐flow events), NoDisturb (duration between high‐ or low‐flow events), MaxMonthQ (maximum monthly discharge), Q99 (99th percentile of daily streamflow), QmaxIDR (interdecile range of annual maxima) and RBI (Richards–Baker Index). 5. Applying the index to data from a probabilistic survey, 34% of stream‐miles in southern California were estimated to be hydrologically altered. One of four management priorities were assigned to each site based on biological condition and hydrologic status: protection (healthy and unaltered, 52% of stream‐miles), monitoring (healthy but altered 4%), evaluation of flow management (unhealthy and altered, 30%) and evaluation of other management (unhealthy but unaltered, 14%). 6. Regionally derived biologically based targets for flow alteration allow catchment managers to prioritise activities and conduct screenings for causal assessments across large spatial scales. Furthermore, regional tools pave the way for incorporation of hydrologic management in policies and catchment planning designed to support biological integrity in streams. Development of regional tools should be a priority where hydrologic alteration is pervasive or expected to increase in response to climate change or urbanisation.

Topobathymetric Model for the Central Coast of California, 1929 to 2017

U.S. Geological Survey (USGS) | August 2nd, 2018

To support the modeling of storm-induced flooding, the USGS Coastal National Elevation Database (CoNED) Applications Project has created an integrated 1-meter topobathyme

To support the modeling of storm-induced flooding, the USGS Coastal National Elevation Database (CoNED) Applications Project has created an integrated 1-meter topobathymetric digital elevation model (TBDEM) for the Central California Coast. High-resolution coastal elevation data is required to identify flood, hurricane, and sea-level rise inundation hazard zones and other earth science applications, such as the development of sediment transport and storm surge models. The new TBDEM consists of the best available multi-source topographic and bathymetric elevation data for the onshore and offshore areas in Central California. The Central California TBDEM integrates 70 different topographic and bathymetric data sources including LiDAR point clouds, hydrographic surveys, single-beam acoustic surveys, and multi-beam acoustic surveys obtained from USGS, NOAA, and USACE. The topographic and bathymetric surveys were sorted and prioritized based on survey date, accuracy, spatial distribution, and point density to develop a model based on the best available elevation data. Because bathymetric data are typically referenced to tidal datums (such as Mean High Water or Mean Low Water), all tidally-referenced heights were transformed into orthometric heights that are normally used for mapping elevation on land (based on the North American Vertical Datum of 1988). The spatial resolution is 1-meter with the general location ranging from Point Conception to the Golden Gate Bridge, and extending offshore to a depth of at least 15 meters. The overall temporal range of the input topography and bathymetry is 1929 to 2017. The topography surveys are from 2008-2015. The majority of the bathymetry is from 1996-2011. Some of the nearshore void zone (not covered by lidar or multibeam) was filled with NOS surveys dating back as far as 1929.

Torres Martinez Tribe Salton Sea Oral Testimony

Salton Sea Authority | September 24th, 2020

 Chairman and Ranking Member, I sincerely appreciate the opportunity to testify today. I am the Tribal Council Chairman of the Torres Martinez Desert Cahuilla (Tribe) an

 Chairman and Ranking Member, I sincerely appreciate the opportunity to testify today. I am the Tribal Council Chairman of the Torres Martinez Desert Cahuilla (Tribe) and a director on the Salton Sea Authority (SSA). I offer this testimony on behalf of both the Tribe and SSA.  I want to begin by thanking Congressman Ruiz (D-Calif.) and Congressman Vargas (D-Calif.) for their hard work to place this issue squarely before the Committee today. The Tribe and SSA view this hearing as a very important beginning of a more robust Congressional effort to drive federal action at the Salton Sea. 

Total and monomethyl mercury in fog water from the central California coast

American Geophysical Union (AGU) | February 11th, 2012

Total Water Management Study for the Central Valley Basin, California, Central Valley Project Intermittent Surface Water Supply, Working Document No. 6

U.S. Bureau of Reclamation (USBR) | April 1st, 1975

Total Water Management Study for the Central Valley Basin, California, Central Valley Project Water Yield Risk Working Document No. 5

U.S. Bureau of Reclamation (USBR) | February 1st, 1975

Total Water Management Study for the Central Valley Basin, California, Interim Water Supply Working Document No. 9

U.S. Bureau of Reclamation (USBR) | March 1st, 1976