Central Coast

The Central Coast region extends from southern San Mateo County down to Santa Barbara in the south and includes redwood forests, foggy coastal terraces, chapparal-covered hills, green valley floors, and semi-arid grasslands. Agriculture and viticulture thrive here with the temperate climate, rich soils, and moderate rainfall, and is central to the economy of this region. The Central Coast region is the most groundwater-dependent region in the state with groundwater being used to meet approximately 80% of agricultural, municipal, and domestic water demands.

Main urban areas are Santa Cruz, Monterey, San Luis Obispo, Santa Maria, and Santa Barbara. Many of the small agricultural communities in this region are considered disadvantaged.
The largest watershed in the region is the Salinas River watershed, which drains 40% of the region. Other watersheds include the Pajaro Basin, San Benito, Carmel, San Luis Obispo, and the Carrizo Plain.
There are 60 alluvial groundwater basins and subbasins in the region; five have been designated as critically overdrafted.
The region receives very little imported water (allocation is 106,000 acre-feet), and only served at this region’s northeastern-most corner.
The Central Coast Regional Water Quality Board oversees this region.

Central Coast

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2016 Annual Report of Hydrogeologic Conditions, Water Requirements, Supplies and Disposition Santa Maria Valley Management Area

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2016 Annual Report of Hydrogeologic Conditions, Water Requirements, Supplies and Disposition Santa Maria Valley Management Area
City of Santa Maria | April 13, 2017...
Summary
This annual report of conditions in the Santa Maria Valley Management Area, for calendar year 2016, has been prepared to meet the reporting conditions...
This annual report of conditions in the Santa Maria Valley Management Area, for calendar year 2016, has been prepared to meet the reporting conditions of the June 30, 2005, Stipulation entered by the Superior Court of the State of California, County of Santa Clara, in the Santa Maria Valley Groundwater Basin litigation. The Stipulation divided the overall Santa Maria Valley Groundwater Basin into three management areas, the largest of which overlies the main Santa Maria Valley (the Santa Maria Valley Management Area, or SMVMA) and is the subject of this report. The other two management areas, the Nipomo Mesa Management Area (NMMA) and the Northern Cities Management Area, are addressed in separate annual reports prepared by others.

The Stipulation, approved and implemented in 2008, specifies that monitoring shall be sufficient to determine groundwater conditions, land and water uses, sources of water supply, and the disposition of all water supplies in the Basin. Annual Reports for the SMVMA are to summarize the results of the monitoring and include an analysis of the relationship between projected water demand and supply. The Stipulation was preserved in the California Court of Appeal (Sixth Appellate District) Decision of November 21, 2012, and in the Superior Court of the State of California (County of Santa Clara) Final Judgment of April 23, 2014. Thus, the Physical Solution criteria for monitoring and managing groundwater in the basin remain.

In accordance with the Stipulation, this report on the SMVMA provides a description of the physical setting and briefly describes previous studies conducted in the groundwater basin, including the long-term monitoring program developed for the SMVMA. As reported herein, the Twitchell Management Authority (TMA) commissioned the preparation of a monitoring program for the SMVMA in 2008, and its complete implementation is expected to provide the data with which to fully assess future conditions. This report describes hydrogeologic conditions in the management area historically and through 2016, including groundwater conditions, Twitchell Reservoir operations, and hydrologic and climatic conditions. As with all previous annual reports (commencing in 2008), the water requirements and supplies for agricultural and municipal uses are accounted, as are the components of water disposition in the SMVMA.

Conclusions drawn regarding water resource conditions are discussed, including any finding of severe water shortage, which is concluded to not be the case through 2016. Finally, recommendations are provided with regard to the intra-basin transfer of water from the SMVMA to the NMMA, possible enhancement of groundwater recharge, expanded assessment of water resource conditions, and continued implementation of the monitoring program for the SMVMA.

Janny Choi from Stanford University's Water in the West discusses the Santa Maria stipulation in the 2014 paper Before the Well Runs Dry: Improving the Linkage Between Groundwater and Land Use Planning.

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2017 Salinas Valley Groundwater Level Contours & Seawater Intrusion Maps
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2017 Salinas Valley Groundwater Level Contours & Seawater Intrusion Maps
Monterey County Water Resources Agency (MCWRA) | April 24, 2018...
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2020 Water Resilience Portfolio (draft)

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2020 Water Resilience Portfolio (draft)
California Natural Resources Agency | January 2, 2020...
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21st century California drought risk linked to model fidelity of the El Niño teleconnection

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21st century California drought risk linked to model fidelity of the El Niño teleconnection
Nature Climate and Atmospheric Science | September 3, 2018...
Summary
Greenhouse gas-induced climate change is expected to lead to negative hydrological impacts for southwestern North America, including California (CA). This includes a decrease...
Greenhouse gas-induced climate change is expected to lead to negative hydrological impacts for southwestern North America, including California (CA). This includes a decrease in the amount and frequency of precipitation, reductions in Sierra snow pack, and an increase in evapotranspiration, all of which imply a decline in surface water availability, and an increase in drought and stress on water resources. However, a recent study showed the importance of tropical Pacific sea surface temperature (SST) warming and an El Niño Southern Oscillation (ENSO)-like teleconnection in driving an increase in CA precipitation through the 21st century, particularly during winter (DJF). Here, we extend this prior work and show wetter (drier) CA conditions, based on several drought metrics, are associated with an El Niño (La Niña)-like SST pattern. Models that better simulate the observed ENSO-CA precipitation teleconnection also better simulate the ENSO-CA drought relationships, and yield negligible change in the risk of 21st century CA drought, primarily due to wetting during winter. Seasonally, however, CA drought risk is projected to increase during the non-winter months, particularly in the models that poorly simulate the observed teleconnection. Thus, future projections of CA drought are dependent on model fidelity of the El Niño teleconnection. As opposed to focusing on adapting to less water, models that better simulate the teleconnection imply adaptation measures focused on smoothing seasonal differences for affected agricultural, terrestrial, and aquatic systems, as well as effectively capturing enhanced winter runoff.

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A 20,000-year record of ocean circulation and climate change from the Santa Barbara basin

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A 20,000-year record of ocean circulation and climate change from the Santa Barbara basin
Nature | October 12, 1995...
Summary
MUCH of the evidence for climate-driven fluctuations in ocean circulation during the past 20,000 years has come from studies of the North Atlantic...
MUCH of the evidence for climate-driven fluctuations in ocean circulation during the past 20,000 years has come from studies of the North Atlantic region. The extent to which such interactions have occurred in other ocean basins, and any associated teleconnec-tions between basins, is poorly understood. Here we present high-resolution palaeoclimate and palaeoceanographic records from a 20,000-year sedimentary sequence from the Santa Barbara basin, on the eastern margin of the North Pacific Ocean. The sequence shows oscillations of the benthic environment between low-oxygen conditions (laminated sediments) during periods of warm climate, and higher-oxygen conditions (non-laminated, bioturbated sediments) during cool intervals. Age differences between coexisting benthic and planktonic foraminifers indicate climate-related changes in the age and source-and, hence, oxygen content-of basin bottom waters. Relatively young bottom waters are associated with the cooler intervals and are considered to reflect high proportions of intermediate waters derived from proximal sources. Conversely, older bottom waters are associated with the warmer intervals and were derived from more distal sources. These climate-driven variations in ocean circulation appear to be synchronous with the main ocean-climate fluctuations in the North Atlantic region, suggesting that a tight coupling mechanism operates between the two basins.

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A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity

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A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity
Freshwater Science, University of Chicago Press Journals | April 18, 2018...
Summary
Conservation scientists have adapted conservation planning principles designed for protection of habi- tats ranging from terrestrial to freshwater ecosystems. We applied current approaches...

Conservation scientists have adapted conservation planning principles designed for protection of habi- tats ranging from terrestrial to freshwater ecosystems. We applied current approaches in conservation planning to prioritize California watersheds for management of biodiversity. For all watersheds, we compiled data on the pre- sence/absence of herpetofauna and fishes; observations of freshwater-dependent mammals, selected invertebrates, and plants; maps of freshwater habitat types; measures of habitat condition and vulnerability; and current manage- ment status. We analyzed species-distribution data to identify areas of high freshwater conservation value that op- timized representation of target taxa on the landscape and leveraged existing protected areas. The resulting priority network encompasses 34% of the area of California and includes ≥10% of the geographic range for all target taxa. High-value watersheds supported nontarget freshwater taxa and habitats, and focusing on target taxa may provide broad conservation value. Most of the priority conservation network occurs on public lands (69% by area), and 46% overlaps with protected areas already managed for biodiversity. A significant proportion of the network area is on private land and underscores the value of programs that incentivize landowners to manage freshwater species and habitats. The priority conservation areas encompass more freshwater habitats/ha than existing protected areas. Land use (agriculture and urbanization), altered fire regimes, nonnative fish communities, and flow impairment are the most important threats to freshwater habitat in the priority network, whereas factors associated with changing climate are the key drivers of habitat vulnerability. Our study is a guide to a comprehensive approach to freshwater conservation currently lacking in California. Conservation resources are often limited, so prioritiza- tion tools are valuable assets to land and water managers.

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A global spatial analysis reveals where marine aquaculture can benefit nature and people

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A global spatial analysis reveals where marine aquaculture can benefit nature and people
PloS ONE | October 9, 2019...
Summary
Aquaculture of bivalve shellfish and seaweed represents a global opportunity to simultaneously advance coastal ecosystem recovery and provide substantive benefits to humanity. To identify marine...
Aquaculture of bivalve shellfish and seaweed represents a global opportunity to simultaneously advance coastal ecosystem recovery and provide substantive benefits to humanity. To identify marine ecoregions with the greatest potential for development of shellfish and seaweed aquaculture to meet this opportunity, we conducted a global spatial analysis using key environmental (e.g., nutrient pollution status), socioeconomic (e.g., governance quality), and human health factors (e.g., wastewater treatment prevalence). We identify a substantial opportunity for strategic sector development, with the highest opportunity marine ecoregions for shellfish aquaculture centered on Oceania, North America, and portions of Asia, and the highest opportunity for seaweed aquaculture distributed throughout Europe, Asia, Oceania, and North and South America. This study provides insights into specific areas where governments, international development organizations, and investors should prioritize new efforts to drive changes in public policy, capacity-building, and business planning to realize the ecosystem and societal benefits of shellfish and seaweed aquaculture.

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A multi-isotope (B, Sr, O, H, and C) and age dating (3H–3He and14C) study of groundwater from Salinas Valley, California: Hydrochemistry, dynamics, and contamination processes

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A multi-isotope (B, Sr, O, H, and C) and age dating (3H–3He and14C) study of groundwater from Salinas Valley, California: Hydrochemistry, dynamics, and contamination processes
American Geophysical Union (AGU) | January 31, 2002...
Summary
The chemical and isotope (11B/10B, 87Sr/86Sr, 18O/16O, 2H/H, 13C/12C, 14C, and 3He/3H) compositions of groundwater from the upper aquifer system of the Salinas Valley...
The chemical and isotope (11B/10B, 87Sr/86Sr, 18O/16O, 2H/H, 13C/12C, 14C, and 3He/3H) compositions of groundwater from the upper aquifer system of the Salinas Valley in coastal central California were investigated in order to delineate the origin and processes of groundwater contamination in this complex system. The Salinas Valley has a relatively deep, confined ‘‘400- foot’’ aquifer, overlain by a ‘‘180-foot’’ aquifer and a shallower perched aquifer, all made up of alluvial sand, gravel and clay deposits. Groundwater from the aquifers have different 14C ages: fossil (14C = 21.3 percent modern carbon (pmc) for the 400-foot aquifer and modern (14C = 72.2–98.2 pmc) for the 180-foot aquifer. Fresh groundwater in all aquifers is recharged naturally and artificially through the Salinas River. The two modes of recharge can be distinguished chemically.We identified several different saline components with distinguishable chemical and isotopic fingerprints. Saltwater intrusion in the northern basin has C1 concentrations up to 1700 mg/L, a Na/Cl ratio less than seawater, a marine Br/Cl ratio, a Ca/Cl ratio greater than seawater, d11B between +17 and +38% and 87Sr/86Sr between 0.7088 and 0.7096. Excess dissolved Ca, relative to the expected concentration for simple dilution of seawater, correlates with 87Sr/86Sr ratios, suggesting base exchange reaction with clay materials. (2) Agriculture return flow is high inNO3 and SO4, with a 87Sr/86Sr = 0.7082,d11B = 19% and d13C between 23 and 17%. The 3H–3He ages (5–17 years) and 14C data suggest vertical infiltration rates of irrigation water of 3–10 m/yr. (3) Nonmarine saline water in the southern part of the valley has high total dissolved solids up to 3800 mg/L, high SO4, Na/Cl ratio >1, d11B between +24 and +30%, and 87Sr/86Sr = 0.70852. This groundwater may have acquired its geochemical signature from leaching of sedimentary rocks associated with the Coast Range marine deposits of Mesozoic to early Cenozoic age. The combination of different geochemical and isotopic fingerprints enables us to delineate the impact of salt sources in different areas of the valley and to reconstruct the origin of the SO4-enriched NO3-depleted saline plume that is located west of the city of Salinas. We suggest that the latter is derived from a mixture of different natural saline waters rather than from anthropogenic contamination.

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A New Technique for Modeling Land Subsidence Facilitates Better Groundwater Management

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A New Technique for Modeling Land Subsidence Facilitates Better Groundwater Management
Stanford Woods Institute for the Environment and the Bill Lane Center for the American West | December 1, 2019...
Summary
Land subsidence – the sudden sinking or gradual settling of Earth’s surface – can occur naturally or be triggered by human activity. One of...

Land subsidence – the sudden sinking or gradual settling of Earth’s surface – can occur naturally or be triggered by human activity. One of the most common human-affected factors is groundwater pumping, a practice that has been steadily increasing due to prolonged periods of drought. Groundwater pumping is so prevalent in some areas that it is severely compromising the quantity and quality of the groundwater as well as the physical structure of the land and aquifer capacity beneath it. Large-scale initiatives for putting water back into the ground, or groundwater recharge, are being implemented in some regions. However, groundwater resource managers still need better information to determine where the land is at greatest risk of subsidence as well as where recharge efforts would be the most effective. Integrating two reliable data gathering sources – helicopter-deployed systems (airborne electromagnetic or AEM technology) that measure electromagnetic fields and satellite-deployed systems (interferometric synthetic aperture radar or InSAR) to measure deformations – offers groundwater managers an improved method for more accurately modeling changes in the land surface related to the pumping and recharge of groundwater. Additionally, the ability to more precisely detect subsidence may offer an early warning system for declining groundwater levels.

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A Path Forward for California’s Freshwater Ecosystems

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A Path Forward for California’s Freshwater Ecosystems
Public Policy Institute of California (PPIC) | December 2, 2019...
Summary
Californians rely on freshwater ecosystems for many things: water supply, hydropower, recreation, fisheries, flood risk reduction, biodiversity, and more. These ecosystems—and the social,...
Californians rely on freshwater ecosystems for many things: water supply, hydropower, recreation, fisheries, flood risk reduction, biodiversity, and more. These ecosystems—and the social, economic and environmental benefits they provide—are part of the state’s natural infrastructure. But they are changing in undesirable ways in response to water and land use, pollution, introduction of non-native species, and a changing climate. Declines in native biodiversity are the most direct measure of these changes, with numerous species now protected by state and federal endangered species acts (ESAs) and many times more likely to need protection in future.

For the past 40 years, the ESAs have played a prominent role in managing the state’s freshwater ecosystems. While this approach has prevented extinctions, it also places an emphasis on reducing harm to listed species, rather than improving overall ecosystem condition necessary to recover their populations. And these laws are not forward-looking enough to help species adapt to changing climate and reduce future species listings. This approach also fuels controversy and litigation due to perceptions about trade-offs between species protection and economic uses of land and water.

To maintain the benefits that Californians derive from their freshwater ecosystems—and arrest the decline of native biodiversity—a new approach is needed. We recommend that the state adopt the principles and practices of ecosystem-based management. This involves the simultaneous management of water, land, and organisms to achieve a desired ecosystem condition that benefits both native biodiversity and human well-being. The goal of ecosystem-based planning is to develop a shared vision for the ecosystem, agreement upon a common set of facts, and a unified plan to achieve it. We are not proposing major reforms to state or federal endangered species acts. Rather, we recommend a shift in the way these acts are implemented.

Ecosystem-based management relies on robust governance frameworks that are transparent, collaborative, and supported by science and secure funding. Many programs are starting to adopt its principles and practices, but much more needs to be done. Actions needed to achieve ecosystem-based objectives include setting aside water budgets for the environment and using this water to improve ecosystem condition and create multiple benefits. Binding comprehensive agreements between regulatory agencies, stakeholders, and water users—developed as part of sustainable watershed management plans—should guide implementation. These plans can be used to align agency actions and permitting and can be adopted by the State Water Board as water quality control plans.

California needs to change course in how it manages freshwater ecosystems to protect the many beneficial uses they provide. Ecosystem-based management offers a more comprehensive, flexible, and adaptive approach, and one that is compatible with existing laws. We believe this approach is better able to improve ecosystem outcomes that benefit both people and nature and respond to today’s challenges while preparing for an uncertain future.

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2016 Annual Report of Hydrogeologic Conditions, Water Requirements, Supplies and Disposition Santa Maria Valley Management Area

2016 Annual Report of Hydrogeologic Conditions, Water Requirements, Supplies and Disposition Santa Maria Valley Management Area

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2017 Salinas Valley Groundwater Level Contours & Seawater Intrusion Maps

2017 Salinas Valley Groundwater Level Contours & Seawater Intrusion Maps

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2020 Water Resilience Portfolio (draft)

2020 Water Resilience Portfolio (draft)

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21st century California drought risk linked to model fidelity of the El Niño teleconnection

21st century California drought risk linked to model fidelity of the El Niño teleconnection

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A 20,000-year record of ocean circulation and climate change from the Santa Barbara basin

A 20,000-year record of ocean circulation and climate change from the Santa Barbara basin

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A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity

A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity

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A global spatial analysis reveals where marine aquaculture can benefit nature and people

A global spatial analysis reveals where marine aquaculture can benefit nature and people

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A multi-isotope (B, Sr, O, H, and C) and age dating (3H–3He and14C) study of groundwater from Salinas Valley, California: Hydrochemistry, dynamics, and contamination processes

A multi-isotope (B, Sr, O, H, and C) and age dating (3H–3He and14C) study of groundwater from Salinas Valley, California: Hydrochemistry, dynamics, and contamination processes

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A New Technique for Modeling Land Subsidence Facilitates Better Groundwater Management

A New Technique for Modeling Land Subsidence Facilitates Better Groundwater Management

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A Path Forward for California’s Freshwater Ecosystems

A Path Forward for California’s Freshwater Ecosystems

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