Ojai Basin Groundwater Management Agency Groundwater Management Plan – 2018 Update

Ojai Basin Groundwater Management Agency | August 30th, 2018

In September, 2014, Governor Jerry Brown signed into law a package of three bills (AB 1739, SB 1168, and SB 1319) known as the Sustainable Groundwater Management Act (“

In September, 2014, Governor Jerry Brown signed into law a package of three bills (AB 1739, SB 1168, and SB 1319) known as the Sustainable Groundwater Management Act (“SGMA”). SGMA provides a framework for sustainable management of groundwater supplies by local authorities, with a limited role for state intervention only if necessary to protect the resource.  The Act requires the formation of local groundwater sustainability agencies that must assess conditions in their local water basins and adopt locally-based management plans. SGMA provides local agencies with the tools and authority to require registration of groundwater wells, measure and manage extractions, require reports and assess fees, and request revisions of basin boundaries, including establishing new subbasins.  High- and medium-priority basins, as defined by the State of California Department of Water Resources (“DWR”), must adopt groundwater sustainability plans within five to seven years, depending on whether the basin is in critical overdraft. Statewide groundwater basins are prioritized based on eight criteria: (1) overlying population, (2) projected growth of overlying population, (3) public supply wells, (4) total water wells, (5) overlying irrigated acreage, (6) reliance on groundwater as the primary source of water (7) impacts on the groundwater, including overdraft, subsidence, saline intrusion, and other water quality degradation, and (8) any other information determined to be relevant by the DWR.  Consistent with its Enabling Legislation, the Ojai Basin Groundwater Management Agency (“OBGMA” or “Agency”) has worked to preserve the quantity and quality of groundwater in the Ojai Valley Groundwater Basin (“Ojai Basin”) for sustainable long-term use since the agency’s establishment in 1991. (The Agency’s Enabling Legislation, SB 534, approved by the Governor October 8, 1991, is also referred to herein as the “OBGMA Act.”) These management efforts have resulted in the protection and maintenance of the long-term water supply for the common benefit of all water users in the Basin. As a result, the Ojai Basin has operated within its “sustainable yield” for the past several decades with no evidence of “undesirable results.”  Per OBGMA Resolution No. 2014-4, adopted by its Board of Directors on December 4, 2014 (copy included as Appendix A), OBGMA is designated as the Groundwater Sustainability Agency (“GSA”) for the Ojai Groundwater Basin. In addition, SGMA identifies OBGMA as an “exclusive local agency” within its statutory boundaries for purposes of implementing the requirements of the Act. (Water Code § 10723(c)(1).) Since OBGMA, in compliance with its Enabling Legislation, already performs many of the planning and management tasks required by SGMA, and sustainable conditions have persisted in the Basin for more than a 10-year period. OBGMA determined it would comply with SGMA by making the Alternative Demonstration of groundwater sustainability authorized by Water Code § 10733.6(b)(3).  To comply with SGMA, OBGMA issued its December 23, 2016 “Report Supporting Alternative Demonstration Made Pursuant to Water Code 10733.6(b)(3). The report contained a physical description of the Basin, including groundwater levels, groundwater quality, information on groundwater-surface water interaction, data on historical and projected water demands and supplies, monitoring and management provisions. The report demonstrated how the Ojai Basin has operated within its “sustainable yield” for the past several decades with no evidence of “undesirable results.”  In sum, OBGMA’s management of the Basin pursuant to its Enabling Legislation has allowed the Agency to make the Alternative Demonstration authorized by SGMA. This 2018 Update to the Agency’s Groundwater Management Plan, undertaken in compliance with its Enabling Legislation, is part of the Agency’s ongoing efforts to preserve the long-term quantity and quality of groundwater in the Ojai Basin for the common benefit all users in the Basin. 

Pajaro Valley Basin Management Plan Groundwater Sustainability Update 2022

Pajaro Valley Water Management Agency (PVWMA) | November 17th, 2021

Pajaro Valley Water Management Agency Basin Management Plan Update

Pajaro Valley Water Management Agency (PVWMA) | February 14th, 2014

Pajaro Valley Water Management Agency Revised Management Plan

Pajaro Valley Water Management Agency (PVWMA) | February 14th, 2002

Pure Water Soquel Groundwater Model Simulation Results

Soquel Creek Water District | June 22nd, 2018

This technical memorandum discusses model simulation groundwater levels, groundwater budget, and particle tracking results to support the Environmental Impact Rep

This technical memorandum discusses model simulation groundwater levels, groundwater budget, and particle tracking results to support the Environmental Impact Report of the Pure Water Soquel project involving replenishment of advanced purified recycled water within Soquel Creek Water District’s (SqCWD’s) service area. Six model simulations have been run using the calibrated GSFLOW model for the Santa Cruz Mid- County Basin (the Basin) where SqCWD’s service area is located. These simulations have different pumping and active replenishment distributions, as follows: Two Projected Existing Conditions (No Project) simulations with SqCWD’spumping distribution reflecting future demand without additional replenishment at proposed recharge wells. Two Project simulations with SqCWD’s pumping distribution reflecting future demand and pumping re-distribution with the addition of replenishment at the Monterey and Cabrillo College Dr. sites (referred to as the Cabrillo-Monterey simulations). These simulations also represent potential replenishment at the Twin Lakes Church site instead of one of the two Cabrillo College Dr. sites. The Twin Lakes Church site is approximately 500-750 feet to the west of the Cabrillo College Dr. sites. Two Project simulations with the same pumping distribution as the Cabrillo- Monterey simulations, but with replenishment at the Monterey and Willowbrook sites (referred to as the Monterey-Willowbrook simulations).Simulation groundwater levels are evaluated for the following effects: Comparison of groundwater levels at coastal monitoring wells to protective elevations estimated to prevent seawater intrusion from further occurring in groundwater supply aquifers. Groundwater levels in the recharge wells to assess whether model results are consistent with estimated capacities for the well, recognizing that site specific testing will be needed to confirm recharge well capacities. Groundwater levels at nearby wells to evaluate effects on operation of those municipal, private, and institutional wells.Simulation groundwater budgets are evaluated for following effects: • Flows entering and leaving the Basin, including flows to and from groundwater in storage and flows offshore to prevent seawater intrusion. • Flows between groundwater and surface water. This memo does not include results for a Cumulative simulation. Information from the City of Santa Cruz to define its Aquifer Storage and Recovery project to be cumulative with Pure Water Soquel is not available or developed at this time. This memo includes results from particle tracking based on the above simulations performed to support the Salt and Nutrient Anti-degradation Study and permitting of the recharge wells. This involves particle tracking of simulated purified, replenishment water to evaluate the fate of the water as it travels in subsurface aquifers. Particle tracking is also used to evaluate travel times of purified, replenishment water, which requires refined analysis near the recharge wells. A scope to superimpose analytic element solutions for recharge and nearby extraction wells onto GSFLOW results to facilitate travel time calculations was approved by SqCWD Board December 18, 2017 and results should be forthcoming in July 2018.

Recommendations to Address the Expansion of Seawater Intrusion in the Salinas Valley Groundwater Basin

Monterey County Water Resources Agency (MCWRA) | October 12th, 2017

This report provides a discussion of the current knowledge and related background information surrounding seawater intrusion pathways and potential impacts ther

This report provides a discussion of the current knowledge and related background information surrounding seawater intrusion pathways and potential impacts thereof on the Salinas Valley Groundwater Basin. This document also serves as a body of evidence to catalogue the findings used to support the recommendations presented herein. Staff is making six recommendations, with each focused on a component that influences, or could be impacted by, the advancement of seawater intrusion. The recommendations are being presented in an order that builds upon the foundational knowledge laid out in the background section of this report, rather than in an order of priority. Each recommendation can be implemented on its own or in concert with the others, and the relative importance of each will be discussed individually in this report. However, the recommendations have been conceptualized as a comprehensive solution that, along with continued operation of projects that have been constructed for the same purpose, have the strongest potential to ensure success in slowing or halting further seawater intrusion when implemented simultaneously.

Resistivity imaging reveals complex pattern of saltwater intrusion along Monterey coast

Journal of Hydrology (Elsevier) | February 22nd, 2017

A coastal region represents a dynamic zone where fresh groundwater in the coastal aquifers interacts with saline ocean water. The location of the freshwater-saltwater int

A coastal region represents a dynamic zone where fresh groundwater in the coastal aquifers interacts with saline ocean water. The location of the freshwater-saltwater interface is governed by the density and pressure differences on the two sides of the interface and the subsurface hydrologic properties that control fluid movement. Saltwater intrusion is the process in which this interface moves landward, with saltwater then occupying parts of the aquifer that were once fresh. While this process has been observed and documented throughout the world for over a century (Bear et al., 1999), climate change, growing water demands, and manipulation of natural hydrologic systems have led to saltwater intrusion being considered a significant threat to future freshwater resources globally (Kinzelbach et al., 2003; Barlow and Reichard, 2009; Werner et al., 2013). Saltwater intrusion can have a number of significant economic and environmental impacts, including diminished freshwater storage capacity, contamination of freshwater production wells, soil salinization, and decreased nutrient laden freshwater discharge to marine ecosystems (Johannes, 1980; Taniguchi et al., 2002; Werner et al., 2013). A number of steps can be taken to attempt to slow the rate of saltwater intrusion, including spatial and temporal changes in the extent of groundwater pumping, in landuse, in surface water diversions, and in artificial recharge (Abarca et al., 2006). What is needed however is a way to prioritize these actions, or combinations of actions, so as to optimize the impact on saltwater intrusion. This requires an accurate understanding of the current distribution of freshwater and saltwater, that can be used to predict future locations in response to these, and other, actions (Sanford and Pope, 2009). Saltwater intrusion is traditionally mapped and monitored using measurements made in wells and predictive flow models (Werner et al., 2013). There are a number of limitations with these methods. Measurements made in wells provide point data, which may fail to capture the spatial complexity in subsurface conditions. Improving spatial coverage with additional wells can be cost prohibitive (Ogilvy et al., 2009). Additionally, salinity measurements from wells can be flux-averaged concentrations, and head measurements in wells are affected by the density of the water column so can be misinterpreted in the presence of unknown salt water, and are susceptible to measurement, instrument, and time lag errors (Carrera et al., 2009; Post and Von Asmuth, 2013). Models are generally calibrated by matching historic head values in wells and/or matching salinity values from well samples (Carrera et al., 2009), thus all the limitations of well data are carried over into the model calibration. Given these limitations there is significant opportunity for additional methods of mapping and monitoring the distribution of saltwater in the subsurface for improved management of coastal aquifers.

Salinas River Watershed Area Salt Modeling

California Central Coast Regional Water Quality Control Board (CCRWQCB) | November 13th, 2015

Tetra Tech supported EPA Region 9 and the Central Coast Regional Water Quality Control Board (CCRWQCB) for an assessment of salt impairments and development of a

Tetra Tech supported EPA Region 9 and the Central Coast Regional Water Quality Control Board (CCRWQCB) for an assessment of salt impairments and development of a salt mass balance in the Lower Salinas River and Reclamation Canal watersheds. This effort can inform development of salt-related TMDLs by the CCRWQCB and a salt and nutrient management plan for the Salinas Valley aquifers. Three reaches have reported 2010 303(d) listings for salt-related impairments in these watersheds including impairments due to chloride, sodium, electrical conductivity, and total dissolved solids – Lower Salinas River, Santa Rita Creek, and Alisal Creek. This report provides data analysis and a literature review (Sections 1 through 5), development of a water and salt mass balance tool (Sections 6 through 8), and salt source assessment (Section 9). The results of the analysis provide a strong foundation for assessing salt sources and understanding salt mass balance in the study area, but can be improved with refined representation of cropland locations, rotations, and irrigation practices.

Salinity distribution in heterogeneous coastal aquifers mapped by airborne electromagnetics

Soil Science Society of America (SSSA) | February 8th, 2011

Understanding the hydrologic setting of any given area is a challenging task, especially considering that the amount of available informaon is ofen very sparse re

Understanding the hydrologic setting of any given area is a challenging task, especially considering that the amount of available informaon is ofen very sparse relative to the size of the area and the complexity of the problem. We used geophysical transient electromagnetic (TEM) data from an airborne SkyTEM instrument to investigate discharge of freshwater from a river catchment into a coastal lagoon area, in support of large-scale hydrologic mapping of the HOBE hydrology research center. Existing hydrologic data indicate possible outflow from the catchment underneath the survey area, a hypothesis that was indeed backed up by our geophysical results. The results revealed a stratified geologic setting frequently incised by buried valleys beneath the lagoon. They also showed that the valleys are saturated with sea water, unlike the layers at the same depth that are probably saturated with brackish water. The salinity decreases with depth in large parts of the lagoon. The salinity distribution in the setting indicates the presence of intricate flow systems beneath the coastal area and the lagoon, and we propose that it is governed by the heterogeneity in the geologic setting. We also demonstrated how water depth as well as salinity can be accurately mapped using SkyTEM in combination with a robust and flexible inversion scheme.

Saltwater Intrusion in Los Angeles Area Coastal Aquifers— the Marine Connection

U.S. Geological Survey (USGS) | August 14th, 2002

Saltwater from the Pacific Ocean is seeping into some Los Angeles Basin coastal aquifers and replacing freshwater. Without treatment, this ground water does not conform t

Saltwater from the Pacific Ocean is seeping into some Los Angeles Basin coastal aquifers and replacing freshwater. Without treatment, this ground water does not conform to drinking-water or agricultural standards. This problem is significant because much of the water used by the nearly 10 million residents of Los Angeles County comes from ground-water sources. Although not all coastal aquifers in the region are at risk, the existing resources are vital and must be protected to maintain adequate supplies of potable water. In the 1950’s, construction began on the first of three “barriers” in an attempt to halt saltwater intrusion. Each barrier consists of a series of injection wells that essentially form a subsurface wall of freshwater designed to keep saltwater from penetrating further into aquifers. The barriers are only partly effective; saltwater continues to infiltrate in some areas. New studies show that the ground-water geohydrology of the coastal aquifers is more complex than previously imagined. U.S. Geological Survey (USGS) scientists, working in cooperation with the Water Replenishment District of Southern California and the Los Angeles County Department of Public Works, are expanding efforts to understand the geologic processes and fluid pathways that control saltwater intrusion.