Monterey County Water Resources Agency Engineering Reports

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  1994 - Hydrogeologic Investigation, Arroyo Seco Cone

  This report presents the findings, analysis, conclusions, and recommendations developed

  as part of an investigation to characterize the hydrogeology of the Arroyo Seco Cone area of the

  Salinas Valley. The purpose of this investigation is to assess the feasibility of developing a seasonal surface water spreading operation utilizing water diverted from the Arroyo Seco in order to enhance ground water recharge in the area. The goal of a project to store water in the ground for subsequent pumping and use is to increase the yield of the Salinas Basin. This investigation defines the hydrogeologic characteristics of the Arroyo Seco Cone area, characterizes the hydrology of the Arroyo Seco and the availability of divertable flows, and estimates the annual recharge that could be achieved through the development of spreading basins.

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  1995 - Monterey County Water Conservation Alternatives - An Analysis

  The major goal of this study ,prepared by Agland Investment Services, Inc. on behalf of the Monterey County Water Resources Agency, was to estimate the direct and regional economic impacts of different policies aimed at encouraging agricultural water conservation in the Salinas Valley. The study also looked at combinations of conservation measures which could provide a least cost conservation contribution to the seawater intrusion problem. Agland concluded that policymakers should consider adopting a least cost approach when they considered the mix of infrastructure projects and urban and rural conservation measures.

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  1995 - North Monterey County Hydrogeologic Study VOLUME I, Water Resource

  The purpose of the investigation was to develop a better understanding of the hydrogeologic setting in the North Monterey County (North County) area and to quantify the various components of water supply and demand. The investigation also focused on the institutional and planning issues associated with the resource limitations and suggests possible responses to these limitations. The investigation was intended to provide the Monterey County Water Resources Agency (MCWRA), as well as the Monterey County Departments of Planning, Building & Inspection and Division of Environmental Health, with data essential to developing a ground water management plan and to support modifications to existing land use policies that may be required to assure a long-term water supply for the area.

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  1996 - Monterey County Hydrogeologic Study, Volume II -- Critical Issues Report and Interim Management Plan, Final Report

  This document was a companion report to the North Monterey County Hydrogeologic Study, Volume I, dated October 1995. The document built from the technical understanding and problem identification developed in Volume I and focuses on key issues relative to developing a management plan for the water resources of the area. These included the interrelated policy, legal and financial issues that complicate the management of the resource. The purpose of the report was to provide an analysis of these issues towards the development of long-range management objectives.

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  2001 - Hydrogeologic Investigation of Salinas Valley Basin in the Vicinity of Fort Ord and Marina Salinas Valley, California - Final Report

  This report evaluated the then current state or potential for seawater intrusion in the city of Marina and the former Fort Order area. Groundwater from this area primarily supplied drinking water wells as opposed to agricultural wells. Aquifers evaluated in this study area include the perched zone or A-aquifer, the Pressure 180-Foot Aquifer (180-Foot Aquifer), the Pressure 400-Foot Aquifer ( 400-Foot Aquifer), the Deep Aquifer, and aquifers within the Purisima and Santa Margarita Formations. The I80-Foot and 400-Foot Aquifers are the focus of this study because both aquifers outcrop along the canyon walls of Monterey Bay where they interface with seawater. Ground water withdrawal from the Salinas Valley, primarily for agricultural irrigation, has steadily resulted in seawater intrusion in the I 80-Foot Aquifer and the 400-Foot Aquifer, proportional to the use of each aquifer. Seawater has currently intruded (as defined by chloride concentrations exceeding 500 mg/L) about 6 miles in the 180-Foot Aquifer and about 3 miles in the 400-Foot Aquifer along the Salinas Valley floor (MCWRA, 2001). Beneath the Marina and former Fort Ord area, seawater has intruded about 2 miles in the 180-Foot Aquifer and about 3 miles in the 400-Foot Aquifer,

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  2003 - Geohydrologic Framework of Recharge and Seawater Intrusion in the Pajaro Valley, Santa Cruz and Monterey Counties, California

  This report provided the Salinas groundwater basin hydrogeology informaion documented since the 1950s in order to provide a better understanding of the advancement of seawater intrusion into groundwater zones. Since the later 1990s, well logs, geopyhsical and lithological data supporting a three-dimensional study of the inter-related ancestral fluvial and alluvial-fan depositional environments making up the groundwater bearing zones (180-Foot and 400-Foot aquifers) and their implications on seawater intrusion pathways.

  The economic importance of a detailed rendition of hydrostratigraphic characteristics was to assist in the construction and placement of future water supply and monitoring wells within the study area. Seawater was intruding into the groundwater zones from the submarine outcrops of and directly into the Pressure 180- and Pressure 400-Foot aquifers. Stratigraphic analysis demonstrated with notably more detailed lithologic data that mixing and vertical migration of seawater was highly possible in several localized areas between the coast and the City of Salinas. Vertical movement of seawater/groundwater is likely across leaky aquitard and areas of the absence of confining clay unit between the Pressure 180-Foot and Pressure 400-Foot Aquifers. It was therefore of importance to the public water supply of the northern Salinas Valley that the 3-D permeability distribution of the lithology be mapped with enough detail to assist in the design of future engineering measures to mitigate the seawater intrusion problem.

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  2003, January - Salinas Valley Water Project Engineer’s Report

  A 2003 Engineer’s Report describing the technical basis for a new assessment that would fund the capital, operation and maintenance costs of the Salinas Valley Water Project. The project would include the operation and maintenance of existing reservoirs, construction of the Nacimiento Dam Spillway Modifications, and construction of the Salinas River Diversion Facility. The project would be implemented by the Monterey County Resources Agency to meet the water supply goals of the Salinas Valley – halting seawater intrusion, continuing conservation of winter flows for recharge of the basin through summer releases, providing flood protection; improving long-term hydrologic balance between recharge and withdrawal, and providing a sufficient water supply to meet water needs through 2030.

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  2007 - El Toro Groundwater Study Monterey County, California

  The primary objective of this study was to evaluate groundwater resource capacity of the El Toro Planning Area and recommend maintaining or revising the B-8 zoning overlay. Additional objectives and tasks completed for this study were consistent with recommendations of the1996 Fugro report and included compiling water well and hydrostratigraphic information for the El Toro Planning Area; conducting aquifer testing; collecting and analyzing water samples from wells; developing a conceptual hydrogeologic model of the El Toro Planning Area; and evaluating hydrogeologic connectivity between existing subareas.

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  2007, November 2 - Zone 2B Proposition 218 Engineer's Report

  A 2007 Engineer’s Report prepared in order to document the basis of the delivery charges for recipients of water delivered from the Salinas River Diversion Facility that necessitated the development of a financing plan for the capital improvements, the annual operation and maintenance costs for those improvements, and the annual operations and maintenance costs of the existing facilities.

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  2015 - Preliminary Engineering Design Report for Control of Non-Winter Drainage at Carr Lake

  Landowners at Carr Lake reported increasing issues with proper drainage of the agricultural fields that made up the vast majority of the former lake bed. The primary driver of the study was the recognition that a more complete understanding of the site topography and hydrology is necessary, both to frame the pertinent issues and to identify any measures that may be appropriate to enhance drainage in the ditch system. Therefore the project work plan included two main fieldwork components, topographic survey and hydrologic monitoring. The fieldwork was followed up by data post processing, mapping, and associated supporting analyses.

  Work was completed under authorization of the Monterey County Water Resources Agency to assess non-winter drainage conditions in the ditch network at Carr Lake, part of the much larger Zone 9 Reclamation Ditch system. The work plan consisted of two principal components: a detailed topographic survey of the main ditch reaches and concurrent hydrologic monitoring in order to better understand the opportunities and constraints that exist with respect to providing efficient dry-season drainage within the on-site ditch network. Field work extended from late April through October of 2014, with subsequent post-processing of data, associated analyses to put the data in a regional and historical context, and preparation of project mapping.

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  2017, October - Recommendations to Address the Expansion of Seawater Intrusion in the Salinas Valley Groundwater Basin

  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. The report also serves as a body of evidence to catalogue the findings used to support the six recommendations presented. Each recommendation can be implemented on its own or in concert with the others, and the relative importance of each is discussed individually in this report. However, the recommendations are 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.