Technical Workshop on Estuarine Habitat in the Bay Delta Estuary

San Francisco Estuary Institute (SFEI) | March 27th, 2012

The Technical Workshop on Estuarine Habitat in the Bay Delta Estuary was initiated by U.S. Environmental Protection Agency (EPA), with support from the Aquatic

The Technical Workshop on Estuarine Habitat in the Bay Delta Estuary was initiated by U.S. Environmental Protection Agency (EPA), with support from the Aquatic Science Center (ASC), to obtain scientific input needed to inform EPA on California’s Comprehensive Review of the 2006 Water Quality Control Plan for the Bay Delta Estuary. Gathering a number of recognized experts on the hydrology and ecology of the Bay Delta was an efficient way to hear current knowledge on estuarine habitat, tools for modeling and assessing conditions, and how biological indicators and ecological processes respond to movement of the low salinity zone.  More specifically, the purpose of the workshop was to: Increase our collective understanding about the attributes of estuarine habitat, and the tools we have for protecting it Characterize the response of biological indicators and ecological processes to changing locations of the low salinity zone (LSZ) Generate scientific information that EPA and others can translate into recommendations that support the State’s Comprehensive Review of the 2006 Water Quality Control Plan (WQCP) for the Bay Delta Estuary The following sections describe planning for the workshop and the workshop process itself. The workshop summary condenses the input from participants during the small workgroup sessions and the final plenary session. It captures the breadth of opinions, judgments, and viewpoints expressed without attempting to fact check statements, or reconcile / synthesize disagreements or contradictions. Finally, the facilitator’s report provides my personal impressions of the workshop and the degree to which it achieved its stated purposes.

Technologies for Passing Fish at Large Dams

California Department of Water Resources (DWR) | June 1st, 2013

Given the possible conditions that may exist in Central Valley streams as the climate warms, many researchers and agencies have recognized the need to evaluate opportunit

Given the possible conditions that may exist in Central Valley streams as the climate warms, many researchers and agencies have recognized the need to evaluate opportunities to provide Central Valley salmonid species access to currently inaccessible habitat (DWR 2008, NMFS 2009, and CA Resources Agency 2009). In addition, Lindley et al. (2007) stated that in order to recover Central Valley salmonids, some populations will need to be established in areas now blocked by dams. “The state should work with dam owners and operators, federal resource management agencies, and other stakeholders to evaluate opportunities to introduce or reintroduce anadromous fish to upper watersheds. Reestablishing anadromous fish, such as salmon, upstream of dams may provide flexibility in providing cold water conditions downstream, and thereby help inform system reoperation.” (CA Resources Agency 2009) The U.S. Bureau of Reclamation dedicates over 1.2 million acre-feet of water, through operation of the Central Valley Project, to fish and wildlife. DWR releases water to meet minimum flow and temperature requirements downstream of Oroville Dam. Climate change may warm rivers and streams, with less water available for ecosystem flow and temperature needs in spring and summer (CA Resources Agency 2009). As temperatures warm, more cold water storage may be needed so that releases can be made to meet temperature requirements downstream. Providing anadromous1 fish passage to areas upstream of reservoirs could eliminate or reduce the need for cold water releases and give water managers additional flexibility in meeting downstream water supply and flood protection needs. In addition, it is prudent to consider fish passage opportunities as part of potential systems reoperations because other agencies are conducting planning efforts for fish passage ...

Tectonic evolution of the Salton Sea inferred from seismic reflection data

Nature Portfolio (Springer Nature) | July 26th, 2009

Oblique extension across strike-slip faults causes subsidence and leads to the formation of pull-apart basins such as the Salton Sea in southern California. The f

Oblique extension across strike-slip faults causes subsidence and leads to the formation of pull-apart basins such as the Salton Sea in southern California. The formation of these basins has generally been studied using laboratory experiments or numerical models. Here we combine seismic reflection data and geological observations from the Salton Sea to understand the evolution of this nascent pull-apart basin. Our data reveal the presence of a northeast-trending hinge zone that separates the sea into northern and southern sub-basins. Differential subsidence (>10 mm yr−1) in the southern sub-basin suggests the existence of northwest-dipping basin-bounding faults near the southern shoreline, which may control the spatial distribution of young volcanism. Rotated and truncated strata north of the hinge zone suggest that the onset of extension associated with this pull-apart basin began after ∼0.5 million years ago. We suggest that slip is partitioned spatially and temporally into vertical and horizontal domains in the Salton Sea. In contrast to previous models based on historical seismicity patterns, the rapid subsidence and fault architecture that we document in the southern part of the sea are consistent with experimental models for pull-apart basins.

Tehachapi Reclaimed Water Project

City of Tehachapi | September 24th, 2024

As part of the proposed project, the City would change the location of application of the secondary treated effluent produced at the Tehachapi WWTP from the agricultural

As part of the proposed project, the City would change the location of application of the secondary treated effluent produced at the Tehachapi WWTP from the agricultural fields near the Tehachapi Municipal Airport to a new location south of the Borrow Pit. Overall WWTP effluent production and WWTP throughput capacity would remain unchanged as would the time of year of application (from April to October).

Tehachapi-Cummings County Water District (TCCWD) v. Armstrong et al

Superior Court of California, County of Kern | February 25th, 1972

From An Evaluation of California’s Adjudicated Groundwater Basins by Langridge et al, UC Davis (2016): "Tehachapi Basin (1, 2) , Cummings Basin, and Brite Basin are

From An Evaluation of California’s Adjudicated Groundwater Basins by Langridge et al, UC Davis (2016): "Tehachapi Basin (1, 2) , Cummings Basin, and Brite Basin are three small groundwater basins in Kern County. Although the basins were adjudicated separately, a single entity, The Tehachapi-Cummings County Water District (TCCWD) serves as Watermaster over the three distinct groundwater basins. An interesting finding is that the Cummings adjudication was never completed. Because of this, its users rely on overlying rights with voluntary agreements, and there is no regulated curtailment of withdrawals. There are only a few big users so it is able to track its water use with relative accuracy, but the basin has significant overdraft. Two of its major users (Stallion Springs and Bear Valley) pump water from the basin that is delivered to offsite users, and they offset the export with imported water. Two-thirds of the residents within Cummings Basin are inmates at the California Correctional Institute."

Tehachapi-Cummings County Water District v. Austin et al

Superior Court of California, County of Kern | December 9th, 1970

Note from "An Evaluation of California’s Adjudicated Groundwater Basins" by Langridge et al: "Tehachapi Basin, Cummings Basin, and Brite Basin are three small ground

Note from "An Evaluation of California’s Adjudicated Groundwater Basins" by Langridge et al: "Tehachapi Basin, Cummings Basin, and Brite Basin are three small groundwater basins in Kern County. Although they were adjudicated as individual basins, the local Tehachapi-Cummings County Water District is the Watermaster for all three basins. Adjudication was deemed desirable so water users could tap into newly available imported water and also secure their water rights. To construct transmission facilities, a federal loan was needed, and adjudication was necessary to assure repayment."

Temescal Basin Groundwater Sustainability Plan

Temescal Basin Groundwater Sustainability Agency | January 27th, 2022

Wishing to provide a framework for cooperative groundwater management and SGMA compliance, the City of Corona (Corona), City of Norco (Norco), and the Home Gardens Coun

Wishing to provide a framework for cooperative groundwater management and SGMA compliance, the City of Corona (Corona), City of Norco (Norco), and the Home Gardens County Water District (HGCWD) executed a Memorandum of Understanding (MOU) in March 2017 establishing the Temescal Basin Groundwater Sustainability Agency (Temescal GSA). In August 2017, the Temescal GSA became the GSA for the Basin by submitting a formation notice to DWR. While Corona is leading this effort, the GSP will be developed jointly among the three agencies, with coordinated implementation toward sustainable management. Due to size, the file has been divided into four parts. Part 1, Part 2, Part 3, Part 4

Temporal and Spatial Patterns of Groundwater Recharge Across a Small Watershed in the California Sierra Nevada Mountains

Frontiers in Water (Frontiers) | May 17th, 2022

Mountain-block groundwater recharge is a crucial freshwater source in arid to semiarid watersheds worldwide; yet its quantification is difficult due to (1) hydrogeologica

Mountain-block groundwater recharge is a crucial freshwater source in arid to semiarid watersheds worldwide; yet its quantification is difficult due to (1) hydrogeological heterogeneities especially in bedrock-dominated regimes, (2) drastic altitudinal ranges in climate, land use and land cover, and (3) mixing with deep groundwater derived from adjacent basins (i.e., interbasin groundwater flow). In this study, we test the utility of soil water-balance (SWB) modeling to quantify mountain-block groundwater recharge in the South Fork Tule River watershed in the California Sierra Nevada Mountains. This 1,018 km2 watershed is instrumented with 3 USGS stream gages that allow for the development of a refined recharge (i.e., baseflow) calibration dataset via multi-objective optimization-based hydrograph separation. The SWB model was used to compute groundwater recharge and other water balance components at a daily time step using a 30-m grid cell size for a 40-year (1980–2019) study period. Mean annual recharge and runoff were estimated at 3.7 in/yr (3.0 m3/s) and 1.4 in/yr (1.2 m3/s), respectively, with modified Nash Sutcliffe Efficiency indices of 0.61 between baseflow and SWB-derived recharge, and 0.90 between hydrograph separation- and SWB-derived runoff. There is a strong correlation between annual recharge and rainfall (Pearson R = 0.95, p < 0.001) which attests to short residence times in the unsaturated zone and the immediate impact of droughts in 1990, 1999, and 2013. However, results of a modified Mann-Kendall trend analysis indicate no directional trends in recharge or runoff throughout the study period. Parameter sensitivity analyses reveal a persistent overprediction of recharge over baseflow that is particularly pronounced in the upper reaches of the watershed. This is likely related to the SWB model only considering soil characteristics at the surface and not simulating the fate of potential recharge below the root zone where it may be impeded from reaching the aquifer by shallow, impermeable bedrock. This limitation should be considered carefully for future water supply projections in this and comparable bedrock-dominated settings.

Temporal changes in the vertical distribution of flow and chloride in deep wells

National Groundwater Association (NGWA) | July 4th, 2005

The combination of flowmeter and depth‐dependent water‐quality data was used to evaluate the quantity and source of high‐chloride water yielded from different depth

The combination of flowmeter and depth‐dependent water‐quality data was used to evaluate the quantity and source of high‐chloride water yielded from different depths to eight production wells in the Pleasant Valley area of southern California. The wells were screened from 117 to 437 m below land surface, and in most cases, flow from the aquifer into the wells was not uniformly distributed throughout the well screen. Wells having as little as 6 m of screen in the overlying upper aquifer system yielded as much as 50% of their water from the upper system during drought periods, while the deeper parts of the well screens yielded 15% or less of the total yield of the wells. Mixing of water within wells during pumping degraded higher‐quality water with poorer‐quality water from deeper depths, and in some cases with poorer‐quality water from the overlying upper aquifer system. Changes in the mixture of water within a well, resulting from changes in the distribution of flow into the well, changed the quality of water from the surface discharge of wells over time. The combination of flowmeter and depth‐dependent water quality data yielded information about sources of high‐chloride water to wells that was not available on the basis of samples collected from nearby observation wells. Changing well design to eliminate small quantities of poor‐quality water from deeper parts of the well may improve the quality of water from some wells without greatly reducing well yield.

Temporal concentrations of Quaternary ammonium compounds in wastewater treatment effluents during the COVID-19 pandemic, 2020–2021

Elsevier | November 19th, 2024