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

City of Santa Maria | April 13th, 2017

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, 20

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.

A New Approach to Accounting for Environmental Water Insights from the Sacramento–San Joaquin Delta

Public Policy Institute of California (PPIC) | November 9th, 2017

How water is apportioned to California’s cities, farms, and the environment can lead to conflict and competition in times of drought. Allocation of water to the environ

How water is apportioned to California’s cities, farms, and the environment can lead to conflict and competition in times of drought. Allocation of water to the environment in particular is poorly accounted for and poorly understood—shortcomings that can affect water policy, decision making, and public perception. This report reviews the state’s long-standing methods for defining and accounting for environmental water and proposes reforms to improve the timeliness, transparency, and detail in the accounting of environmental water allocation.

Accounting for California’s Water

Public Policy Institute of California (PPIC) | July 13th, 2016

Understanding California’s water balance sheet—how much there is, who has claims to it, and what is actually being “spent”—is key to effectively managing the st

Understanding California’s water balance sheet—how much there is, who has claims to it, and what is actually being “spent”—is key to effectively managing the state’s limited water supply in support of a healthy economy and environment. The latest drought has spotlighted serious gaps and fragmentation in California’s water accounting system. In this report, we identify gaps in California’s water information systems. We recommend that the state adopt an overarching goal of modernizing its water accounting, and that key state agencies—supported by an oversight committee of key stakeholders and independent experts—develop and adopt a common accounting framework. We outline a dozen priority actions to strengthen water accounting by: improving measurements and estimates of water availability and use; firming up legal claims on water rights and water reserved for the environment; establishing protocols, standards, and models for transparent water accounting at all levels across the state; and making water information more available and accessible to water managers, water users, policymakers, and the public.

Annual Ground-Water Discharge by Evapotranspiration from Areas of Spring-Fed Riparian Vegetation Along the Eastern Margin of Death Valley, 2000–02

U.S. Geological Survey (USGS) | July 1st, 2006

Considering Water Use Efficiency for the Environmental Sector

California Department of Water Resources (DWR) | April 29th, 2010

The goal of this report is to provide a starting point from which the water planning community can move toward improving the allocation of water within the environmental

The goal of this report is to provide a starting point from which the water planning community can move toward improving the allocation of water within the environmental sector. To facilitate that process, this report presents: 1.  A discussion that highlights the water community’s points of agreement on the concept of analyzing the application of water to the environment 2.  A term, Managed Environmental Water Use Efficiency (MEWUE), to reflect that concept, and a definition of that term 3.  A survey of existing methods that could be used to develop MEWUE 4.  Suggestions about how to proceed with implementing MEWUE Based on our analysis, we found that there was genuine interest in understanding and improving how water is allocated to the environment. The idea of maximizing environmental benefits for a given amount of allocated water is a unifying thread among stakeholder interests. We focus on this idea throughout the report as the central concept that MEWUE is intended to achieve. We propose a new term to reflect the stated concerns of stakeholders that other terms, Environmental Water Use Efficiency and Ecosystem Restoration Water Use Efficiency, did not fully address. We propose Managed to indicate that MEWUE does not evaluate the environment’s use of water per se but rather the effectiveness of water in controlled systems. We propose Environmental to reflect the range of “uses” of water in the ecosystem, including ecosystem maintenance, restoration, and water quality. Lastly, we support the use of the word Efficiency because efficiency communicates the intent of maximizing benefit for a given amount of water, providing a basis for comparison of the benefits obtainable from different uses of that water. MEWUE: a mechanism to analyze alternative uses of managed environmental water to determine which allocation of a given amount of water will maximize environmental benefits, and a means to improve decision-making over time. We address the issue of why having an explicit decision-making mechanism is essential. It is hard to allay the fears that some have of incorrectly measuring environmental benefits. However, it is even more difficult to claim that decisions based on implicit measures and beliefs are better for the environment than those based on some imperfect but explicit consideration of environmental benefits.

Depletion and Capture: Revisiting “The Source of Water Derived from Wells”

National Groundwater Association (NGWA) | May 28th, 2014

A natural consequence of groundwater withdrawals is the removal of water from subsurface storage, but the overall rates and magnitude of groundwater depletion and capture

A natural consequence of groundwater withdrawals is the removal of water from subsurface storage, but the overall rates and magnitude of groundwater depletion and capture relative to groundwater withdrawals (extraction or pumpage) have not previously been well characterized. This study assesses the partitioning of long‐term cumulative withdrawal volumes into fractions derived from storage depletion and capture, where capture includes both increases in recharge and decreases in discharge. Numerical simulation of a hypothetical groundwater basin is used to further illustrate some of Theis' (1940) principles, particularly when capture is constrained by insufficient available water. Most prior studies of depletion and capture have assumed that capture is unconstrained through boundary conditions that yield linear responses. Examination of real systems indicates that capture and depletion fractions are highly variable in time and space. For a large sample of long‐developed groundwater systems, the depletion fraction averages about 0.15 and the capture fraction averages about 0.85 based on cumulative volumes. Higher depletion fractions tend to occur in more arid regions, but the variation is high and the correlation coefficient between average annual precipitation and depletion fraction for individual systems is only 0.40. Because 85% of long‐term pumpage is derived from capture in these real systems, capture must be recognized as a critical factor in assessing water budgets, groundwater storage depletion, and sustainability of groundwater development. Most capture translates into streamflow depletion, so it can detrimentally impact ecosystems.

Development and Calibration of a Two-Dimensional Digital Model for the Analysis of the Ground-Water Flow System in the San Antonio Creek Valley, Santa Barbara County, California

U.S. Geological Survey (USGS) | August 1st, 1985

Evaluating Micrometeorological Estimates of Groundwater Discharge from Great Basin Desert Playas

National Groundwater Association (NGWA) | March 6th, 2018

Groundwater availability studies in the arid southwestern United States traditionally have assumed that groundwater discharge by evapotranspiration (ETg) from desert play

Groundwater availability studies in the arid southwestern United States traditionally have assumed that groundwater discharge by evapotranspiration (ETg) from desert playas is a significant component of the groundwater budget. However, desert playa ETg rates are poorly constrained by Bowen ratio energy budget (BREB) and eddy‐covariance (EC) micrometeorological measurement approaches. Best attempts by previous studies to constrain ETg from desert playas have resulted in ETg rates that are within the measurement error of micrometeorological approaches. This study uses numerical models to further constrain desert playa ETg rates that are within the measurement error of BREB and EC approaches, and to evaluate the effect of hydraulic properties and salinity‐based groundwater density contrasts on desert playa ETg rates. Numerical models simulated ETg rates from desert playas in Death Valley, California and Dixie Valley, Nevada. Results indicate that actual ETg rates from desert playas are significantly below the uncertainty thresholds of BREB‐ and EC‐based micrometeorological measurements. Discharge from desert playas likely contributes less than 2% of total groundwater discharge from Dixie and Death Valleys, which suggests discharge from desert playas also is negligible in other basins. Simulation results also show that ETg from desert playas primarily is limited by differences in hydraulic properties between alluvial fan and playa sediments and, to a lesser extent, by salinity‐based groundwater density contrasts.

Evapotranspiration Rate Measurements of Vegetation Typical of Ground-Water Discharge Areas in the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada and Adjacent Areas in Nevada and Utah, September 2005–August 2006

U.S. Geological Survey (USGS) | July 1st, 2007

Geohydrology and Simulated Response to Ground-Water Pumpage in Carson Valley, A River-Dominated Basin in Douglas County, Nevada, and Alpine County, California

U.S. Geological Survey (USGS) | May 2nd, 1986

This investigation of the ground-water hydrology in Carson Valley was conducted from 1980 through 1985 by the U.S. Geological Survey, in cooperation with Douglas County.

This investigation of the ground-water hydrology in Carson Valley was conducted from 1980 through 1985 by the U.S. Geological Survey, in cooperation with Douglas County. The purpose of the study was to: (1) collect, compile, and analyze hydrologic data to quantify the hydrology of the valley and to enhance the understanding of the valley's geohydrologic system; and (2) develop a ground-water model that would simulate the response of the hydrologic system to applied stresses and that could be used to estimate the probable hydrologic effects of various development alternatives. This report presents the results of the investigation. Work began with a gravity survey in 1980 to determine the depth to bedrock in Carson Valley; the results are discussed in detail in a separate publication (Maurer, 1986). From 1981 to 1983, work included: (1) measurement of water-level fluctuations and surface-water runoff, (2) drilling of additional observation wells, (3) collection of ground-water pumpage data and measurement of pump efficiencies, and (4) compilation of existing data reports and drillers 1 logs to obtain estimates of geohydrologic characteristics of the ground-water reservoir. Development of a water budget and initial estimates of hydraulic conductivities and specific yield were accomplished in 1983. From 1983 to 1985, the ground-water model was developed and calibrated, and simulations of possible ground-water development were made. The model, which represents a compilation of all available data, was used to (1) test estimates of the geohydrologic characteristics of the ground-water reservoir, (2) evaluate the components of the water budget for the basin, (3) enhance the understanding of the hydrologic flow system in the basin, and (4) simulate the effect of various possible developmental alternatives on Carson River outflow, evapotranspiration, ground-water levels, and ground-water storage in the valley.