TOOLS FOR ASSESSING GROUNDWATER-SURFACE WATER CONNECTIVITY UNDER THE SUSTAINABLE GROUNDWATER MANAGEMENT ACT Key findings and recommendations from a one-day workshop on assessing, monitoring and quantifying interconnected surface waters under SGMA
Prepared by Tara Moran, Tom Gleeson, Melissa Rohde, Ben Kerr and Christina Babbitt
February 2019
Acknowledgements
The authors would like to thank all those who participated in the dialogue and provided feedback during the development of this report. We would also like to thank Bea Gordon for her help with this report. In addition, the authors would like to thank Megan Glatzel and Athena Serapio for organizing meeting logistics. Finally, thank you to the S.D. Bechtel, Jr. Foundation for their ongoing financial support for this work.
Report Reviewers (alphabetical order)
Jessica Bean, State Water Resources Control BoardLetty Belin, ConsultantSam Boland-Brien, State Water Resources Control BoardMichael Kiparsky, UC BerkleyErik Ringelberg, The Freshwater TrustAnthony Saracino, ConsultantLeon Szeptycki, Stanford University
Thank you to all of our reviewers. Your comments and suggestions helped to significantly improve the report. The authors would like to note that reviewers were not asked to endorse the report’s conclusions or recommendations, nor did they see the final version of the report. As a result, responsibility for the final content of this report rests entirely with the report’s authors.
Suggested Citation: Moran, T., Gleeson, T., Rohde, M., Kerr, B., and Babbitt, C. (2018). Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act. Dialogue report prepared by Water in the West, University of Victoria, The Nature Conservancy, Foundry Spatial and the Environmental Defense Fund. Stanford Digital Repository. Available at: https://purl.stanford.edu/mn804jy8641.
This report was developed out of a workshop hosted by Water in the West in partnership with The University of Victoria, Foundry Spatial, Environmental Defense Fund and the Nature Conservancy.
TABLE OF CONTENTS
Introduction ..................................................................................................................................................................... 1
Focus area summaries .................................................................................................................................................... 2
1) Accounting for beneficial uses and users in GSP development and implementation ................................................. 2
Findings ............................................................................................................................................................. 2
2) Identifying physical or analytical approaches for characterizing, quantifying and monitoring ISW ............................. 3
Findings ............................................................................................................................................................. 4
3) Using hydrological modeling to assess effects of groundwater depletion on ISW and streamflow depletions ............. 5
Box 1. Overview of analytical and numerical model codes ..................................................................................... 5
Findings ............................................................................................................................................................. 6
4) Understanding the functionality and use of decision support tools from other jurisdictions ....................................... 6
Findings ............................................................................................................................................................. 8
Summary ......................................................................................................................................................................... 9
Summary findings and recommendations .................................................................................................................. 9
For GSAs ................................................................................................................................................................. 9
For state and federal agencies .................................................................................................................................. 9
References .................................................................................................................................................................... 11
Appendix A. Workshop attendees ................................................................................................................................ 12
Appendix B. Workshop agenda ..................................................................................................................................... 13
Appendix C. Workshop questionnaire ........................................................................................................................... 16
Appendix D. Supplementary tables .............................................................................................................................. 17
Table D1. Legal and regulatory requirements for interconnected surface water under SGMA. ..................................... 17
Table D2. Regulatory code pertaining to the consideration of beneficial uses and users under SGMA ......................... 18
Table D3. Overview of tools and approaches for assessing interconnected surface water and streamflow depletions. . 19
Table D3. References ............................................................................................................................................. 25
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INTRODUCTIONIn 2014, California enacted the Sustainable Groundwater Management Act (SGMA), which requires local agencies to develop and implement groundwater sustainability plans (GSPs) in all groundwater basins designated by the California Department of Water Resources (DWR) as high or medium priority1 by 2020 or 2022, depending on basin condition.2 For the first time in California’s history, agencies managing groundwater under SGMA must assess the impacts of groundwater pumping on water supply and surface water flows and avoid “significant and unreasonable adverse impacts on beneficial uses of the surface water.”3
SGMA’s legal and regulatory requirements pertaining to interconnected surface water – defined in SGMA as, “surface water that is hydraulically connected at any point by a continuous zone to the underlying aquifer and the overlying surface water is not completely depleted.”4 – represent a significant step forward in recognizing the interconnected nature of surface water and groundwater and for managing this resource accordingly. However, because groundwater-surface water connectivity was not a common management consideration prior to the enactment of SGMA, many basins lack data or models or technical capacity to adequately characterize interconnected surface water (ISW) and evaluate the impacts of groundwater pumping on these systems. Thus, meeting legal and regulatory requirements related to ISW may be hindered by a lack of information about both the location and timing of such waters, as well as the many beneficial uses and users that they support.
In March 2018, Water in the West, The University of Victoria, Foundry Spatial, The Nature Conservancy (TNC) and Environmental Defense Fund co-hosted a workshop on tools to assess ISW under SGMA. The workshop, which included a small, select group of hydrologists, water managers, water lawyers, nongovernmental organizations (NGOs) and academia, focused on four main areas:
1) Accounting for beneficial uses and users in GSP development and implementation;
2) Identifying physical or analytical approaches for characterizing, quantifying and monitoring ISW;
3) Using hydrological modeling to assess the effects of groundwater pumping on ISW and streamflow depletions; and
4) Understanding the functionality and use of decision support tools from other jurisdictions
This report summarizes key findings from the one-day workshop and a short questionnaire completed by workshop participants during the day. A list of workshop attendees, the workshop agenda and workshop questionnaire can be found in Appendices A-C, respectively.
1 The California Department of Water Resources (DWR) assigns all 517 of California’s alluvial groundwater basins to one of four categories. These categories are high, medium, low and very low priority (See California Water Code (CWC) §10722.4(a)). Groundwater basins designated as medium and high priority basins are subject to SGMA and must develop groundwater sustainability plans.
2 Groundwater sustainability plans (GSPs) must be completed by January 31, 2020, for the 21 groundwater basins that the DWR has designated as being in a state of critical overdraft. GSPs for all remaining high and medium priority basins must be completed by January 31, 2022. (CWC §10720.7.)
3 CWC §10721(x)(6)
4 23 California Code of Regulations (CCR) §351(o)
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FOCUS AREA SUMMARIES1) Accounting for beneficial uses and users in GSP development and
implementation
SGMA requires GSPs to avoid undesirable result #6, which is “significant and unreasonable adverse impacts on beneficial uses of the surface water.” The State Water Resources Control Board (SWRCB) formally defines 23 beneficial uses of surface water and groundwater.5 In addition to agricultural, domestic and municipal water uses, many beneficial uses of surface water may be impacted by depletions of interconnected surface waters, including habitat, refuges and reserves, cold or warm water ecosystems, estuarine and terrestrial ecosystems and others. For more detail on beneficial uses and the legal and regulatory requirements related to ISW under SGMA see Belin (2018), Cantor et al. (2018), and Tables D1 and D2 in Appendix D.
In addition to avoiding impacts on beneficial uses of surface water, SGMA also requires groundwater sustainability agencies (GSAs) (the local agencies developing GSPs) to “consider the interests of all beneficial uses and users of groundwater [emphasis added]”, including, but not limited to: (1) Overlying groundwater rights holders, including agricultural and domestic well owners; (2) Municipal well operators and public water systems; (3) Land use planning agencies; (4) Environmental groundwater users; (5) Hydrologically connected surface water users; (6) The federal government; (7) California Native American tribes; (8) Disadvantaged communities; and (9) Entities monitoring and reporting groundwater elevations in all or a part of a groundwater basin managed by the groundwater sustainability agency.6
Evaluating the impacts of groundwater depletions on beneficial users of surface water and groundwater will require GSAs to undertake several actions. First, GSAs will need to develop a comprehensive understanding of the location, quantity and timing of ISW7 as of the SGMA benchmark date (January 1, 2015) and thereafter. Second, GSAs will need to assess what the beneficial users of groundwater and surface water in each basin are, understand the conditions under which groundwater depletions in the basins would result in “significant and unreasonable impacts” on these users and translate these impacts into measurable objectives, interim milestones and minimum thresholds that can be incorporated into their GSPs.8 Finally, GSAs will need to develop a monitoring network with data of sufficient quality, frequency and distribution to characterize ISW in the basins and evaluate how they change as a result of Plan implementation.9 GSAs should take an iterative approach to understanding and monitoring the impacts of groundwater pumping on surface water and groundwater uses and users in their basin.
Findings
• Only basins with ISW are potentially vulnerable to undesirable result #6; thus GSAs will need to establish if there is ISW in their basins. At present, there is limited information about the spatial and temporal connectivity of surface water and groundwater systems in many groundwater basins throughout the state. 23 CCR §§353.2 and 354.16 require DWR to provide information, where possible, to identify ISW and “estimate the quantity and timing of depletions in those systems.”
• Uncertainty about the extent and timing of ISW should not hinder management actions and the development of meaningful
5 California State Water Resources Control Board (2014). Beneficial Use Definitions. Available at: https://www.waterboards.ca.gov/about_us/performance_report_1617/plan_assess/docs/bu_definitions_012114.pdf. Some Regional Water Resources Control Boards have identified additional beneficial uses that have also been approved by the SWRCB. Id., p. 5.
6 CWC §10723.2
7 23 CCR §354.16
8 23 CCR §§ 354.28 and 354.30
9 23 CCR §354.32
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measurable objectives and interim milestones. To account for this uncertainty, local agencies will need to take a conservative approach in developing the measurable objectives and minimum thresholds to ensure that they are protective of beneficial uses of groundwater and surface water. These thresholds can be revised over time as understanding of the system increases and the impacts of groundwater pumping on beneficial users becomes clearer.
• SGMA does not override preexisting laws that protect specific beneficial uses or users. For example, the Federal or State Endangered Species Act may have certain instream conditions (e.g., flow or temperature) that are impacted by groundwater pumping. Instream flow criteria to protect state or federally listed endangered species will need to be maintained regardless to what conditions existed on Jan 1, 2015. See Belin (2018) and Cantor et al. (2018) for more information on other legal requirements related to ISW under SGMA.
• GSAs will need to identify all beneficial uses and users of surface water and groundwater within a basin. Beneficial users should be included in discussions to define significant and unreasonable adverse impacts and the design of protective minimum thresholds.
• In some basins, existing instream flow criteria adopted by the SWRCB will serve as the basis for minimum thresholds for surface water depletions.10 However, even where instream flow criteria exist, GSAs will need to consult with local beneficial users to ensure that these criteria are protective of all interests.
• In basins without existing instream flow criteria, insight from DWR, SWRCB, the California Department of Fish and Wildlife and other state and federal agencies on the methodologies used for the development of instream flow criteria may be helpful in guiding GSA development of minimum thresholds for ISW.
• Research by Carlisle et al. (2016) provides estimates of natural monthly streamflow for streams throughout California which may be useful in estimating impacts to streamflow resulting from groundwater pumping and other factors.
• The Groundwater Resources Hub (TNC) provides maps, guidance and case studies of groundwater dependent ecosystems (GDEs) – one category of beneficial users of groundwater listed in CWC §10723.2.11
2) Identifying physical or analytical approaches for characterizing, quantifying and monitoring ISW
The technical challenges in determining the location and timing of ISW are substantial (Barlow and Leake 2012). These challenges are particularly acute in California because groundwater and surface water are considered legally separate resources governed by different legal regimes. This legal separation is partially responsible for the lack of information about the spatial extent and timing of ISW in most groundwater basins in the state. Additionally, there is a lack of technical expertise about the tools, methods and techniques to identify and monitor for ISW at the local and regional scale. Building on work by Cantor et al. (2018), workshop participants developed Table D3 in Appendix D, which provides an overview of some of the field- and model-based methods for assessing ISW, their benefits and their limitations.
SGMA allows for multiple GSAs and GSPs within a single groundwater basin.12 Where multiple GSPs exist within a basin, GSAs must use the same data and methodologies in developing their water balance, sustainable yield, groundwater extraction data and other assumptions.13 Data related to ISW are not explicitly addressed in this section of the legislation. However, inconsistencies in data and methods used to quantify ISW and the impacts of groundwater pumping on ISW may lead to conflicts between
10 California Department of Fish and Wildlife, (2018) CDFW Instream Flow Recommendations Map. Available at: https://www.wildlife.ca.gov/Conservation/Watersheds/InstreamFlow/Recommendations.
11 More information on the Groundwater Resources Hub can be accessed at: https://www.scienceforconservation.org/products/groundwater-resource-hub.
12 CWC §§10723(d) and 10727(b)
13 CWC §10727.6
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groundwater pumpers and surface water users. GSAs should seek to develop consistent and integrated data, methodologies and modeling approaches for assessing ISW within a basin and between hydrologically connected basins.
Findings
• Many of the methods described in the Table D3 in Appendix D are summarized in Barlow and Leake (2012); Rosenberry and LaBaugh (2008); and at the U.S. Geological Survey (USGS) Hydrogeophysics Branch website.14
• The importance of high quality, high resolution stream gauging data for understanding and modeling a watershed cannot be overstated. Despite having the technology and knowledge of its importance, insufficient stream gauge data remains a major limitation in watershed hydrology research and management in California. Federal, state, regional and local agencies should work together to support the ongoing maintenance and expansion of California’s stream gauging network. These efforts should include installing more gauges and ensuring adequate long-term funding for the maintenance of stream gauge networks.
• The majority of stream gauge data in California comes from the California Data Exchange Center and the U.S. Geological Survey (USGS). Despite the importance of stream gauge data for the evaluation of ISW, recent analysis by TNC found that 86% of the significant streams in California (those that drain over 1,200 acres) are poorly gauged, and that the number of gauged streams across the state has declined substantially over time.15
• Recent work by Miller et al. (2018) highlights the importance of stream gauge data to support water management decisions, including water infrastructure operation.
• Meeting the legal and regulatory requirements related to ISW will require significant technical expertise and resources. DWR should develop expertise and guidance on local-scale identification, assessment and monitoring of ISW under SGMA. Developing this expertise at the state level and sharing this expertise with resource-strapped GSAs would significantly improve their ability to meet the legal requirements relating to ISW under SGMA.
• Local agencies should seek to develop consistent and integrated data, methodologies and modeling approaches for assessing ISW within a basin and between hydrologically connected basins. Whenever possible, state and federal agencies, NGOs and academic institutions should support the development of consistent ISW assessment and monitoring efforts by coordinating their work on the topic to ensure consistency in messaging and outputs.
• DWR and the SWRCB should take an iterative approach in evaluating GSPs, particularly with respect to ISW.
• During GSP development GSAs should focus on: 1) correctly characterizing ISW that occurs within their basins; 2) installing a monitoring network capable of providing insight into spatial and temporal exchanges between the surface water and groundwater systems over time; 3) identifying all beneficial uses of groundwater and surface water in the basin, and conditions that would constitute significant and unreasonable impacts; 4) translating potentially significant and unreasonable impacts into minimum thresholds that are protective of beneficial users; and 5) developing a model that can be used to quantify the impacts of groundwater pumping on ISW.
14 United State Geological Survey, (2018). Hydrogeophysics Branch website. Available at: https://water.usgs.gov/ogw/bgas/.
15 The Nature Conservancy, (2018). Gage Gap Map. Available at https://water.usgs.gov/ogw/bgas/.
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3) Using hydrological modeling to assess effects of groundwater depletion on ISW and streamflow depletions
Well calibrated hydrologic models can be used to understand how hydrologic systems are likely to respond to future changes in climate, land use or other factors and to estimate the impacts of groundwater pumping on interconnected surface water (Barnett et al. 2012).
23 CCR §354.28(c)(6)(B) requires the use of a numerical groundwater and surface water model, “or an equally effective method, tool, or analytical model” to quantify surface water depletion in GSPs. Workshop discussions focused on the relative advantages and disadvantages of using numerical hydrological models and analytical models to model streamflow depletions. See Box 1 for more information on the differences between analytical and numerical model codes.
Box 1. Overview of analytical and numerical model codes
Analytical model codes describe the physical processes of groundwater flow or contaminant transport using one or more governing equations. These model codes are generally a greatly simplified version of a three-dimensional flow problem and generally assume that the system remains uniform through space and time.
While analytical model codes are not typically used to represent changing conditions (DEQ 2014), they are much faster and cheaper to build and run than their numerical counterparts. Importantly, they provide valuable insight into the fundamental behavior of an aquifer system in response to pumping, recharge or groundwater-surface water connection and how it relates to its hydrogeologic properties.
Numerical model codes solve the same mathematical equations as analytical models. However, to accommodate complex aquifer system and boundary condition geometries, numerical models divide the physical system being modeled into discrete cells or elements. The ability to model across both space and time enables the simulated environment (e.g., hydrogeologic conditions, pumping rates, etc.) to change.
Because of the complexity of aquifer systems and the extensive input requirements for numerical models, these model codes can be labor-intensive to build and calibrate (Anderson et al. 2015). Additionally, numerical model codes require sufficient data for model input and calibration (DEQ 2014). However, when developed and calibrated appropriately numerical models can serve as a powerful tool to simulate geologically complex or more developed hydrologic systems and to forecast long-term changes to the system.
The simplifying assumptions used in analytical models generally mean that these models require less data than numerical models and are faster and easier to build, run and maintain. Thus, analytical models are commonly used in regions where data is sparse (Barnett et al. 2012), to evaluate the impacts of pumping on surface water bodies in relatively underdeveloped regions (Huggins et al. 2018), or as a “screening” tool or “first-order” estimate of pumping impacts (Reeves et al. 2009).
By contrast, numerical models are capable of representing more complex aquifer systems and thus can provide a much more nuanced understanding of a system. Well-developed and calibrated numerical models can serve as a powerful tool to simulate geologically complex or more developed hydrologic systems and forecast long-term changes to the system. However, these models are labor-intensive to develop and calibrate, and require extensive data inputs.
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Integrating the use of analytical and numerical models, as is done in other states, may be a means of capturing the best attributes of both model types. For example, analytical models, which produce rapid, accessible information can be used as screening level tools across larger areas. More complex, detailed numerical models can be developed in areas with more data and with more complex management structures. See Section 4 for an example of an analytical model used as a screening tool in Michigan to differentiate between groundwater withdrawals that are not likely to cause an adverse resource impact upon streams and those that may have an adverse impact.
Findings
• There are many good summaries on the use of hydrologic models for estimating ISW, guidelines for their use and descriptions of model limitations, including Barlow and Leake (2012); Barnett et al. (2012); and Rathfelder (2016).
• There are advantages and disadvantages to using analytical versus numerical hydrological models for identifying and quantifying the impacts of groundwater pumping on streamflow. Integrating the use of analytical and numerical models across groundwater basins may be a means of capturing the best attributes of both model types. For example, in Michigan, an analytical model is used as a “screening tool” to identify groundwater withdrawals that are likely to have an adverse impact on fish populations, which then triggers a site-specific review that includes the use of a numerical model. Section 4 has more information on the Michigan Tool.
• As discussed in section 2, stream gauge data plays an essential role in developing and calibrating both analytical and numerical hydrologic models. Funding to support and expand the maintenance and development of the stream gauging network in California would provide foundational data to GSAs with ISW, as well as support many other hydrologic analyses.
• DWR is currently developing the Sacramento Valley Groundwater-Surface Water Simulation Model (SVSim) to, among other things, evaluate ISW in California’s Sacramento Valley (CDWR 2018). Similar steps should be undertaken to improve the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim) – DWR’s hydrological model for California’s Central Valley. Doing so would improve consistency in groundwater modeling efforts within and between hydrologically connected basins, reduce redundancy and inefficiencies in model development and improve evaluation of ISW in California’s Central Valley.
• Further research to assess the performance of analytical and numerical models in similar scenarios could provide insight and guidance on the level of model complexity necessary and useful for groundwater management decisions in different hydrologic and institutional environments.
4) Understanding the functionality and use of decision support tools from other jurisdictions
There is a growing interest in using data integration, visualization and modeling tools to guide water management decisions. In this session, workshop participants heard from people involved in the development of two online tools used to support water management decisions in Michigan and British Columbia, Canada. These tools are the Michigan Water Withdrawal Assessment Tool (WWAT),16 an online screening tool used to identify new or increased groundwater withdrawals that may have adverse impacts on fish populations in Michigan (Hamilton and Seelback 2010), and the BC Water Tool,17 which integrates public, water-related data to support decisions for water use approvals and licenses.
16 http://www.deq.state.mi.us/wwat/(S(acxkwjuipqawhap521vwyq4m))/default.aspx
17 http://www.bcwatertool.ca/
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Michigan Water Withdrawal Assessment Tool
The Michigan Water Withdrawal Assessment Tool (WWAT) is an online tool used to assess proposed new or increased water withdrawals. This tool was developed as part of the water-withdrawal process mandated by State of Michigan Public Act 34 of 2006, which sought to determine “whether the proposed [water] withdrawal may cause an adverse impact to the waters of the state or to the water-dependent natural resources of the state.”
The WWAT combines three models: an analytical groundwater model, a streamflow model and a fish impact model, which rely on a mix of public and proprietary data (Huggins et al. 2018). Users input information about the proposed pumping withdrawal, including withdrawal source, pumping capacity and location, well depth, aquifer type and pumping schedule (Reeves et al. 2009). Withdrawal impacts are categorized into one of four adverse resource impact categories, which range from Zone A (low risk) to Zone D (high risk). Withdrawals categorized as Zone D are subject to additional agency review (Reeves et al. 2009).
WWAT has been in use for approximately 10 years and is considered to be the most prominent online conjunctive management screening tool to date (Huggins et al. 2018). It has relatively low data requirements and is easy to use. Despite its success, there are some lessons that have been learned during tool implementation. First, when developing online screening tools, agencies need to anticipate the resources and expertise necessary to conduct site-specific reviews when they are triggered, including the capacity to develop and run more complex models of the system, and processes for reviewing data and analysis from applicants. Second, tool development and implementation must include stakeholder outreach and communication to ensure transparency in the screening process. Finally, relatively minor differences in interpretation of the system can lead to distrust in the tool. Maintaining dialogue with users is essential to ensure these discrepancies are caught and addressed before they come issues.
BC Water Tool
Developed by Foundry Spatial for the British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development and the British Columbia Oil and Gas Commission, the BC Water Tool is a map-based water information tool used by applicants and the province to make decisions about water withdrawal permits.
The BC Water Tool uses analytical models to estimate streamflow depletions over the simulation period. Inputs to the BC tool include surface water data, groundwater extraction data and hydrogeologic data. Many of these inputs are pulled from publicly available sources, which can then be supplemented with higher-resolution data where available. For example, stream networks and flow rates have been mapped globally by Lehner et al. (2008). Similarly, some hydrogeologic data such as porosity and permeability have been mapped globally (Gleeson et al. 2014). The intent of the BC tool is to provide users with the ability to consider questions relating to water supply, demand and ecosystem needs at the stream, aquifer or well scale.
The ability to overlay higher resolution data enables the BC tool to be used in different settings; however, tool limitations exists. These limitations include data availability and the simplifying assumptions necessary to facilitate the use of all available data (Huggins et al. 2018). Unlike the WWAT, the BC tool does not serve as a screening tool for approving new water rights: rather, it outputs streamflow depletions that can be used by resources managers to support management decisions.
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The WWAT and the BC Water Tool demonstrate the value of online decision support tools to guide water management decisions. Key findings and lessons learned from these tools are summarized below.
Findings
• Data and visualization tools can help inform water management decisions. However, these tools require significant time, data and resources to develop. Thus, agencies developing tools should ensure sufficient budgetary and personnel commitments for tool development, ongoing support/maintenance and tool outreach and communication.
• Additionally, when developing online screening tools, agencies need to anticipate the resources and expertise necessary to conduct site-specific reviews when they are triggered, including the capacity to develop and run more complex models of the system, and processes for reviewing data and analysis from applicants.
• Bearing in mind the considerations outlined above, the state should consider developing screening or decision support tools to support the management of ISW.
• The development and implementation of screening or decision support tools should include extensive and ongoing stakeholder outreach and communication to ensure that tools meet user needs, are simple to use and understand, and communicate outputs in a comprehensible manner. Additionally, the stakeholder outreach process should seek to identify and address issues associated with tool development or implementation early in the process before they cause distrust in the tool.
• Tool developers should clearly convey data sources, methods, model assumptions and tool limitations.
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SUMMARYGroundwater and surface water are physically connected and are manifestations of the same resource. Developing a comprehensive understanding of the timing, nature and extent of this connection, as the basis to assess streamflow depletions resulting from groundwater pumping and other impacts on beneficial uses and users, as required under SGMA, will not be easy. However, it is essential for sustainable water management. Taking a thoughtful and systematic approach to developing a coordinated groundwater monitoring network that can serve as the basis for model development and project planning to address SGMA’s ISW requirements will provide local and state agencies with the data and tools necessary to manage this precious resource for all users in the future.
Summary findings and recommendations
For GSAs
• Only basins with ISW are subject to undesirable result #6, thus GSAs will need to establish whether there is ISW in their basins. At present, there is limited information about the spatial and temporal connectivity of surface water and groundwater systems in many groundwater basins throughout the state.
• GSAs with ISW should assess existing stream gauge networks in their basin and prioritize additional stations, where necessary.
• For existing guidance on legal challenges see Belin (2018) and Cantor et al. (2018). Building on work by Cantor et al. (2018), workshop participants developed Table D3 in Appendix D, which provides an overview of the some of the field- and model-based methods for assessing ISW, their benefits and their limitations.
• There are advantages and disadvantages to using analytical versus numerical hydrological models for identifying and quantifying the impacts of groundwater pumping on streamflow. Integrating the use of analytical and numerical models across groundwater basins may be a means of capturing the best attributes of both model types. For example, in Michigan, an analytical model is used as a “screening tool” to identify groundwater withdrawals that are likely to have an adverse impact on fish populations, which then triggers a site-specific review that includes the use of a numerical model. Section 4 has more information on the Michigan Tool.
• GSAs should take an iterative approach to understanding and monitoring the impacts of groundwater pumping on surface water and groundwater uses and users in their basin.
For state and federal agencies
• DWR should develop expertise and guidance on local-scale identification, assessment and monitoring of ISW under SGMA. Developing this expertise at the state level and sharing this expertise with resource-strapped GSAs would significantly improve their ability to meet the legal and regulatory requirements relating to ISW under SGMA.
• Additional guidance, data and support from state and federal agencies and others would dramatically improve GSAs’ assessments of ISW in their basins. Specifically,
– As outlined in 23 CCR § 354.16(f), DWR should provide data on ISW for all high and medium priority basins.
– DWR, SWRCB, the California Department of Fish and Wildlife, NGOs and other institutions should summarize the methodologies used for the development of instream flow criteria to assist GSAs in basins without existing instream flow criteria with the development of minimum thresholds for ISW.
– Similar to work done on the Sacramento Valley Groundwater-Surface Water Simulation Model (SVSim), DWR should modify the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim) to better evaluate ISW.
– DWR and/or the State Board should consider developing an online decision support tool for ISW.
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• The importance of high quality, high resolution stream gauging data for understanding and modeling a watershed cannot be overstated. Despite the availability of gauging technology and the understanding of its importance, insufficient stream gauge data remains a major limitation in watershed hydrology research and management in California. Federal, state, regional and local agencies should work together to support the ongoing maintenance and expansion of California’s stream gauging network. These efforts should include installing more gauges, providing more grants to support the existing gauge network, and ensuring an adequate long-term funding stream for the maintenance of stream gauge networks.
• DWR and the State Board will need to take an iterative approach in evaluating GSPs, particularly with respect to ISW.
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REFERENCESBarlow, P. M., & Leake, S. A. (2012). Streamflow depletion by wells: understanding and managing the effects of groundwater pumping on streamflow. U.S. Geological Survey Circular 1376. Available at: https://pubs.usgs.gov/circ/1376/.
Barnett, B., L.R. Townley, V. Post, R.E. Evans, R.J. Hunt, L. Peeters, S. Richarson, A.D. Werner, A. Knapton, and A. Boronkay. (2012). Australian groundwater modeling guidelines, Waterlines report, No. 82, National Water Commission, Canberra. Available at: http://www.groundwater.com.au/media/W1siZiIsIjIwMTIvMTAvMTcvMjFfNDFfMzZfOTYwX0F1c3RyYWxRyY5fZ3JvdW5kd2F0ZXJfb-W9kZWxsaW5nX2d1aWRlbGluZXMucGRmIl1d/Australian-groundwater-modelling-guidelines.pdf.
Belin, A. (2018). Guide to Compliance with California’s Sustainable Groundwater Management Act: How to Avoid the “Undesirable Result” of “Significant and Unreasonable Adverse Impacts on Beneficial Uses of Surface Waters”. Stanford Digital Repository. Available at: https://purl.stanford.edu/kx058kk6484.
[CDWR 2018] California Department of Water Resources. (2018). Central Valley Groundwater-Surface Water Simulation Model. Available at: https://water.ca.gov/Library/Modeling-and-Analysis/Central-Valley-models-and-tools/C2VSim.
Cantor, A., D. Owen, T. Harter, N.G. Nylen, and M. Kiparsky. (2018). Navigating Groundwater-Surface Water Interactions under the Sustainable Groundwater Management Act. Available at: https://www.law.berkeley.edu/wp-content/uploads/2018/03/Navigating_GW-SW_Interactions_under_SGMA.pdf.
Carlisle, D. M., Nelson, S. M., & May, J. (2016). Associations of stream health with altered flow and water temperature in the Sierra Nevada, California. Ecohydrology, 9(6), 930-941.
Gleeson, T., Moosdorf, N., Hartmann, J., & Van Beek, L. P. H. (2014). A glimpse beneath earth’s surface: GLobal HYdrogeology MaPS (GLHYMPS) of permeability and porosity. Geophysical Research Letters, 41(11), 3891-3898.
Hamilton, D. A., & Seelbach, P. W. (2010). Determining environmental limits to streamflow depletion across Michigan. The book of the states, 42, 534-537.
Huggins, X., Gleeson, T., Eckstrand, H., & Kerr, B. (2018). Streamflow Depletion Modeling: Methods for an Adaptable and Conjunctive Water Management Decision Support Tool. Journal of the American Water Resources Association, 54(5), 1024-1038. doi.org/10.1111/1752-1688.12659.
Lehner, B., Verdin, K., & Jarvis, A. (2008). New global hydrography derived from spaceborne elevation data. Eos, Transactions American Geophysical Union, 89(10), 93-94.
Miller, K., N. Green Nylen, H. Doremus, A. Fisher, G. Fogg, D. Owen, S. Sandoval Solis, J. Viers, and M. Kiparsky. (2018). California’s Stream Flow Monitoring System is Essential for Water Decision Making. Center for Law, Energy & the Environment, UC Berkeley School of Law, Berkeley, CA. 4 pp. Available at: https://www.law.berkeley.edu/research/clee/research/wheeler/stream-monitoring/.
Rathfelder, K. (2016). Modelling Tools for Estimating Effects of Groundwater Pumping on Surface Waters. Province of BC, Ministry of Environment, Water Science Series WSS2016-09. Available at: http://a100.gov.bc.ca/appsdata/acat/documents/r51878/tools4streamdepletion_1484093475019_4092907088.pdf.
Reeves, H.W., Hamilton, D.A., Seelbach, P.W., and Asher, A.J., (2009). Ground-water-withdrawal component of the Michigan water-withdrawal screening tool. U.S. Geological Survey Scientific Investigations Report 2009–5003. Available at: https://pubs.usgs.gov/sir/2009/5003/pdf/sir2009-5003_web.pdf.
Rosenberry, D. O., & LaBaugh, J. W. (2008). Field techniques for estimating water fluxes between surface water and ground water. U.S. Geological Survey Techniques and Methods 4-D2. Available at: https://pubs.usgs.gov/tm/04d02/.
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 11
APPENDIX A. WORKSHOP ATTENDEES Christina Babbit – Environmental Defense Fund
Letty Belin – Water in the West
Jessica Bean – California State Water Board
Oliver Brandes – Polis Project
Daren Carlisle – United State Geological Survey
Mary Fahey – Colusa County Resources Conservation District
Graham Fogg – University of California, Davis
Laura Foglia – University of California, Davis
Tom Gleeson – University of Victoria
Bea Gordon – Water in the West
Megan Glatzel – Water in the West
Mary Hill – University of Kansas
Jeanette Howard – The Nature Conservancy
Jay Jasperse – Sonoma County Water Agency
Ben Kerr – Foundry Spatial
Michael Kiparsky – UC Water
Rosemary Knight – Stanford Unviersity
Sally Liu – The Naturel Conservancy
Tara Moran – Water in the West
Howard Reeves – United States Geological Survey
Erik Ringleberg – Freshwater Trust
Melissa Rhode – The Nature Conservancy
Leon Szeptycki – Water in the West
Gus Tolley – University of California, Davis
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 12
APPENDIX B. WORKSHOP AGENDA
Tools and Methods for Assessing Groundwater-Surface Water Connectivity under SGMA
Stanford University March 12, 2018
Water in the West, the University of Victoria, Foundry Spatial, The Nature Conservancy, and the Environmental Defense Fund are co-hosting a workshop entitled, “Tools for Assessing Groundwater-Surface Water Connectivity under SGMA”. The full-day workshop will take place on March 12, 2018 from 8:30 am to 5 pm at Stanford University.
This workshop seeks to:
1. Engage with individuals and entities working on groundwater and surface water connectivity and groundwater dependent ecosystems under SGMA;
2. Examine recent research and tool development to assess research gaps and areas to coordinate or collaborate research effort to help address surface water depletions under SGMA; and
3. Where new research or tools are necessary, identify their potential role in water management decisions, the data needs, essential functionality, and potential users, locations and partners for pilot studies.
Meeting DetailsWhen: March 12, 2018 (1 day)Where: Room 299, Y2E2 Building, 473 Via Ortega, StanfordHotel: Stanford Guest House
Dinner DetailsWhen: March 12, 2018, 5:00 pmWhere: Tea Room, Shriram Building, 443 Via Ortega
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 13
AGENDA
Monday, March 12, 2018
8:15 – 9:00 Light Breakfast and Registration
9:00 – 9:20 Welcome and Introductions Leon Szeptycki, Water in the West Tara Moran, Water in the West Tom Gleeson, University of Victoria
9:20 – 10:25 Session 1: Why are we here? (65 mins) What are groundwater hydrologists, groundwater managers, the state and others most worried about with
respect to groundwater-surface water requirements under SGMA?
Moderator: Leon Szeptycki, Water in the West
Presentations:
• Groundwater-surface water connectivity in hydrologic science: Tom Gleeson, University of Victoria (15 mins)
• Legal and regulatory requirements of interconnected surface water under SGMA: Jessica Bean, California State Water Resources Control Board (15 mins)
• Navigating Groundwater-Surface Water Interactions under the Sustainable Groundwater Management Act: Michael Kiparksy, UC Water (15 mins)
Discussion (20 mins)
10:25 – 10:35 Time to fill out Session 1 questions
10:35 – 12:00 Session 2: Can we go with the flow, people? (85 mins) What are the concerns in considering multiple beneficial uses of interconnected surface waters under SGMA?
How can these approaches address these concerns? Where is additional work needed?
Moderator: Tara Moran, Water in the West
Presentations:
• A Framework for Unimpaired Minimum Streamflow Requirements: Daren Carlisle, United States Geological Survey (15 mins)
• EDF’s Proposed Approach for Compliance with Surface Water Depletion Requirements in SGMA: Christina Babbitt, Environmental Defense Fund (15 mins)
• California’s Groundwater Dependent Ecosystems: Jeanette Howard, The Nature Conservancy (15 mins)
Discussion (40 mins)
12:00 – 12:10 Time to fill out Session 2 questions
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 14
12:10 – 1:00 Lunch (50 mins)
1:00 – 2:40 Session 3: Tools of the trade (100 mins) How can we leverage existing data and knowledge to improve water literacy? Is there a role for screening level
tools, to support decision making and identification of where more complex field investigations and numerical modeling is needed?
Moderator: Mary Hill, The University of Kansas
Presentations:
• B.C. Water Tool: Ben Kerr, Foundry Spatial (30 mins)
• The Michigan Tool: Howard Reeves, United States Geological Survey (30 mins)
Discussion (40 mins)
2:40 – 2:50 Time to fill out Session 3 questions
2:50 – 3:10 Break (20 minutes)
3:10 – 4:20 Session 4: To model or not to model? (70 mins) What level of model complexity is necessary and useful for groundwater management decisions in different
hydrologic and institutional environments?
Moderator: Laura Foglia, University of California, Davis
Presentations:
• Comparison of Analytical and Numerical Models: Tom Gleeson, University of Victoria (15 mins)
• Lessons Learned from Groundwater Modeling in California and Beyond: Graham Fogg, University of California, Davis (15 mins)
Discussion (40 mins)
4:20 – 4:30 Time to fill out Session 3 questions
4:30 – 4:50 Summarize key findings and next steps (20 mins) Leon Szeptycki, Water in the West Tom Gleeson, University of Victoria
4:50 – 4:55 Wrap-up, next steps
4:55 – 5:00 Time to fill out wrap up questions
5:00 Reception and Dinner
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 15
APPENDIX C. WORKSHOP QUESTIONNAIRESession 11. What are you most worried about with respect to groundwater-surface water requirements under SGMA?
2. How do you anticipate addressing (or think GSAs should address) the concerns outlined above in groundwater sustainability plans under SGMA?
Session 21. What is appealing about the approaches presented during session 2?
2. Do you have outstanding questions about these approaches and their potential application?
Session 31. What is appealing about the tools presented during session 3 of the workshop?
2. Do you have outstanding questions about these tools and their potential application?
Session 41. What is appealing about:
a. Analytical models for addressing interconnected surface waters under SGMA?
b. Numerical models for addressing interconnected surface waters under SGMA?
2. Do you have outstanding questions about these models and their potential application under SGMA?
a. Analytical models
b. Numerical models
Wrap up1. After today’s meeting, what are you most worried about with respect to groundwater-surface water requirements under SGMA?
Have your concerns changed or remained the same? Why?
2. What would most help you or others best address this concern on the necessary timeline?
3. Can we reach out to you for additional information? If so, please include your name below and your areas of interest or technical expertise.
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 16
APPENDIX D. SUPPLEMENTARY TABLES Table D1. Legal and regulatory requirements for interconnected surface water under SGMA.
Legal requirements
GSPs must: • Avoid chronic lowering of groundwater levels that result in significant and unreasonable depletion of supply (CWC 10721(w)(1))
• Avoid depletions of interconnected surface waters that have significant and unreasonable adverse impacts on beneficial uses of the surface water (CWC 10721(w)(6))
• Include impacts on GDEs (CWC 10727.4(l))
• Develop monitoring and management protocols to detect changes in surface flow…(CWC 10727.2(d)(2))
Regulatory requirements
GSPs must: • Include a hydrogeologic conceptual model characterizing surface water-groundwater interactions (CCR 354.14)
• Identify interconnected surface waters in the basin, including estimates of quantity and timing of depletions (CCR 354.16(f)
• Include water budgets that include estimates of inflows and outflows to and from the groundwater systems by and to surface water systems (354.18(b)(2&3)); historical and projected groundwater and surface water interactions using a numerical model or an equally effective method, tool, or analytical model (CCR 354.18(e))
• Include minimum thresholds for depletions of interconnected surface water avoid undesirable results. Minimum thresholds must consider the location, quantity, and timing of depletions (CCR 354.28(c)(6))
• Include a monitoring network capable of demonstrating the hydraulic gradients between principal aquifers and surface water features using monitoring wells (CCR 354.34(c)(1)); characterizing spatial and temporal exchanges between surface water and groundwater, and sufficiently calibrate models used to determine the impact of groundwater pumping on surface water depletions (CCR 354.35(c)(6))
• Evaluate and modify monitoring protocols to ensure that adequate detail about “site-specific” surface water and groundwater conditions and assess the effectiveness of management actions including in highly variable spatial and temporal conditions (CCR 354.38)
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 17
Table D2. Regulatory code pertaining to the consideration of beneficial uses and users under SGMA
Table provided by Melissa Rohde, The Nature Conservancy.
GSP Regulation Section
Required Consideration of Beneficial Uses and Users in Groundwater Sustainability Plans
Beneficial Uses and Users
of Groundwater
of Surface Water
Admin InfoGSP Regulations §354.10 (a)Each Plan shall include a description of the beneficial uses and users of groundwater in the basin
Yes
Basin Setting
GSP Regulations §354.16(d)Each Plan shall provide a description of groundwater quality issues that may affect the supply and beneficial uses of groundwater
Yes
GSP Regulations §354.18(e)Each Plan shall rely on the best available information and science to quantify and evaluate projected water budget conditions and the potential impacts to beneficial uses and users of groundwater
Yes
Sustainable Management Criteria
GSP Regulations §354.26(b)(3)Each Plan shall describe potential effects on the beneficial uses and users of groundwater that may occur or are occurring from undesirable results
Yes
GSP Regulations §354.28(b)(4)Each Plan shall establish minimum thresholds that quantify groundwater conditions for each sustainability indicator and describe how minimum thresholds may affect the interests of beneficial uses and users of groundwater.
Yes
GSP Regulations §354.28 (c)(6)The minimum threshold for depletions of interconnected surface water shall be the rate or volume of surface water depletions caused by groundwater use that has adverse impacts on beneficial uses of the surface water and may lead to undesirable results
Yes
Monitoring Networks
GSP Regulations §354.34 (b)(2)Monitor impacts to the beneficial uses or users of groundwater Yes
GSP Regulations §354.34(c)(6)When establishing a monitoring network for Depletion of Interconnected Surface water, monitor factors that may be necessary to identify adverse impacts on beneficial uses of the surface water
Yes
GSP Regulations §354.34(f)(3)The density of monitoring sites and frequency of measurements required to demonstrate short-term, seasonal, and long-term trends are based shall be based upon impacts to beneficial uses and users of groundwater that could affect the ability of that basin to meet the sustainability goal
Yes
GSP Regulations §354.38(e)(3)The Monitoring frequency and density of monitoring sites shall be adjusted to provide an adequate level of detail about site-specific surface water and groundwater conditions to assess the effectiveness of management actions under circumstances where adverse impacts to beneficial uses and users of groundwater may exist
Yes
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 18
Tabl
e D3
. Ov
ervi
ew o
f too
ls a
nd a
ppro
ache
s fo
r as
sess
ing
inte
rcon
nect
ed s
urfa
ce w
ater
and
str
eam
flow
dep
letio
ns.
Tabl
e m
odifi
ed fr
om C
anto
r et a
l. (2
018)
.
Tool
s/M
etho
dsDe
scrip
tion
Appl
icat
ion/
Use
Case
Bene
fits/
Lim
itatio
nsCa
se S
tudi
es/K
ey R
efer
ence
s
Fiel
d-ba
sed
met
hods
Stre
amflo
w g
agin
gSt
ream
flow
mon
itorin
g pr
ovid
es a
co
ntin
uous
reco
rd o
f stre
am d
isch
arge
at
a p
artic
ular
site
ove
r tim
e. I
is
the
com
bine
d in
terp
reta
tion
of: 1
) st
ream
gag
ing
data
, a c
ontin
uous
m
easu
rem
ent o
f sur
face
wat
er
heig
ht a
long
a s
tream
or r
iver
, and
2)
dis
char
ge e
stim
ates
, per
iodi
c m
easu
rem
ents
of t
he v
olum
e of
wat
er
at a
spe
cific
loca
tion
alon
g a
stre
am,
whi
ch a
re re
late
d to
one
ano
ther
us
ing
a st
age-
disc
harg
e re
latio
nshi
p.
Stre
amflo
w m
easu
rem
ents
take
n at
tw
o or
mor
e si
tes
alon
g a
river
can
be
use
d to
est
imat
e st
ream
flow
gai
ns
or lo
sses
bet
wee
n m
easu
rem
ent
loca
tions
.
Stre
amflo
w d
ata
prov
ides
info
rmat
ion
foun
datio
nal
to u
nder
stan
ding
a s
urfa
ce w
ater
sys
tem
and
its
conn
ectio
n to
the
broa
der h
ydro
logi
c sy
stem
. It c
an
be u
sed:
1. A
s an
inpu
t in
hydr
olog
ic m
odel
s an
d fo
r mod
el
calib
ratio
n,
2. T
o de
term
inin
g im
pact
s of
gro
undw
ater
pum
ping
on
loca
l sur
face
wat
er b
odie
s,
3. T
o es
timat
e an
d m
onito
r sur
face
wat
er d
eple
tions
,
4. T
o m
onito
r stre
amflo
w fo
r aqu
atic
hea
lth (e
.g.
inst
ream
flow
requ
irem
ents
)
5. T
o es
timat
e ba
seflo
w, a
nd
6. T
o as
sess
the
impa
cts
of c
hang
ing
cond
ition
s on
a
stre
am (e
.g. g
roun
dwat
er p
umpi
ng, l
and
use
chan
ge, c
limat
e ch
ange
, etc
.) w
hen
mea
sure
d th
roug
h tim
e.
BEN
EFIT
S
1. R
elat
ivel
y si
mpl
e an
d lo
w c
ost i
f stre
amflo
w g
ages
al
read
y ex
ist a
t app
ropr
iate
loca
tions
, and
2. C
an p
rovi
de a
n es
timat
e of
stre
amflo
w
cont
ribut
ion
from
gro
undw
ater
.
LIM
ITAT
ION
S
1. R
equi
res
cont
inuo
us s
tream
gag
ing
at a
ppro
pria
te
(ofte
n m
ultip
le) l
ocat
ions
, whi
ch c
an b
e di
fficu
lt an
d ex
pens
ive
to m
aint
ain,
2. M
ay n
ot p
rovi
de a
full
pict
ure
of c
ompl
ex
grou
ndw
ater
dyn
amic
s, a
nd
3. C
hang
es in
the
syst
em m
ust b
e la
rger
than
m
easu
rem
ent a
ccur
acy
to b
e de
tect
ed.
Witt
enbe
rg, H
., &
Siva
pala
n, M
. (19
99).
Barlo
w a
nd L
eake
(201
2).
Grou
ndw
ater
leve
l m
onito
ring
The
long
-ter
m m
onito
ring
of
grou
ndw
ater
leve
ls (t
ypic
ally
via
a m
onito
ring
or p
rodu
ctio
n w
ell)
at a
pa
rtic
ular
loca
tion
over
tim
e.
Grou
ndw
ater
leve
l mon
itorin
g pr
ovid
es in
form
atio
n fo
unda
tiona
l to
unde
rsta
ndin
g a
grou
ndw
ater
sys
tem
an
d its
con
nect
ion
to th
e br
oade
r hyd
rolo
gic
syst
em.
Thes
e da
ta c
an:
1. B
e us
ed a
s an
inpu
t for
hyd
rolo
gic
mod
els
and
for
mod
el c
alib
ratio
n,
2. M
onito
r cha
nge
in g
roun
dwat
er le
vels
thro
ugh
time,
3. B
e co
mbi
ned
with
gro
undw
ater
leve
ls th
roug
hout
th
e ba
sin
to d
eter
min
e hy
drau
lic g
radi
ents
and
flo
w p
atte
rns,
4. B
e co
mbi
ned
with
gro
undw
ater
pum
p te
sts
to
dete
rmin
e hy
drau
lic c
ondu
ctiv
ity,
5. B
e co
mbi
ned
with
stre
amflo
w m
onito
ring
to
asse
ss th
e de
gree
of h
ydro
logi
c co
nnec
tivity
be
twee
n sy
stem
s, a
nd
6. B
e co
mbi
ned
with
stre
amflo
w m
onito
ring
to
asse
ss th
e im
pact
s of
gro
undw
ater
pum
ping
on
surf
ace
wat
er d
eple
tions
.
BEN
EFIT
S
1. R
elat
ivel
y si
mpl
e an
d lo
w c
ost i
f exi
stin
g m
onito
ring
netw
ork
is s
uffic
ient
, and
2. U
sefu
l for
mon
itorin
g lo
ng-t
erm
tren
ds a
nd
impa
cts
to b
enefi
cial
use
rs w
hen
com
bine
d w
ith
othe
r app
roac
hes.
LIM
ITAT
ION
S
1. M
ay b
e ov
erly
sim
ple
for a
ll an
alys
es, p
artic
ular
ly w
here
hig
h sp
atia
l and
tem
pora
l inf
orm
atio
n ab
out
inte
rcon
nect
ed s
urfa
ce w
ater
is re
quire
d,
2. H
ighl
y de
pend
ent o
n th
e qu
ality
of t
he m
onito
ring
netw
ork,
incl
udin
g th
e ty
pes
of w
ells
bei
ng
mon
itore
d, th
e sp
atia
l cov
erag
e of
the
wel
ls, t
he
tem
pora
l mon
itorin
g fre
quen
cy, d
ista
nce
from
su
rfac
e w
ater
bod
ies,
and
the
com
plex
ity o
f the
sy
stem
, and
3. M
ay n
ot a
ccou
nt fo
r tim
e la
gs in
gro
undw
ater
pu
mpi
ng.
Hall
et a
l. (2
018)
.
Curr
ell,
M.J
. (20
16).
Rose
nber
ry e
t al.,
(200
8).
Tayl
or, C
. J.,
& Al
ley,
W. M
. (20
01).
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 19
Tool
s/M
etho
dsDe
scrip
tion
Appl
icat
ion/
Use
Case
Bene
fits/
Lim
itatio
nsCa
se S
tudi
es/K
ey R
efer
ence
s
Seep
age
met
ers
Seep
age
met
ers
mea
sure
the
exch
ange
of w
ater
bet
wee
n su
rfac
e w
ater
bod
ies
and
grou
ndw
ater
at a
po
int o
r site
sca
le.
Seep
age
met
ers
can:
1. M
easu
re fl
uxes
bet
wee
n su
rfac
e w
ater
bod
ies
and
grou
ndw
ater
,
2. M
easu
re lo
sses
from
unl
ined
irrig
atio
n ca
nals
,
3. M
onito
r sur
face
wat
er d
eple
tion,
and
4. B
e co
mbi
ned
with
dat
a fro
m h
ydra
ulic
po
tent
iom
eter
s (s
ee b
elow
) to
estim
ate
loca
l-sca
le
vert
ical
hyd
raul
ic c
ondu
ctiv
ity.
BEN
EFIT
S
1. L
ow c
ost a
nd s
impl
e to
use
.
LIM
ITAT
ION
S
1. N
umer
ous
sour
ces
of e
rror
exi
st,
2. N
ot w
ell s
uite
d fo
r sur
face
wat
er b
odie
s w
ith
curr
ents
or f
ast w
ater
, roc
ky s
edim
ent,
or v
ery
soft
sedi
men
t, an
d
3. P
rovi
des
loca
lized
info
rmat
ion
that
can
not
gene
rally
be
appl
ied
mor
e br
oadl
y.
Rose
nber
ry e
t al.,
(200
8).
Hydr
aulic
po
tent
iom
eter
sHy
drau
lic p
oten
tiom
eter
s pr
ovid
e an
est
imat
e of
loca
l-sca
le v
ertic
al
hydr
aulic
con
duct
ivity
in s
urfa
ce w
ater
bo
dy s
edim
ents
.
Hydr
aulic
pot
entio
met
ers
can:
1. P
rovi
de in
form
atio
n ab
out r
elat
ive
chan
ges
in
loca
l-sca
le, v
ertic
al h
ydra
ulic
con
duct
ivity
in
sedi
men
ts o
f a s
urfa
ce w
ater
bod
y, a
nd
2. B
e co
mbi
ned
with
mea
sure
men
ts fr
om a
see
page
m
eter
(see
abo
ve) t
o es
timat
e lo
cal-s
cale
hy
drau
lic c
ondu
ctiv
ity.
BEN
EFIT
S
1. P
rovi
des
insi
ght i
nto
rela
tive
varia
tion
in v
ertic
al
hydr
aulic
con
duct
ivity
in s
edim
ents
bel
ow s
urfa
ce
wat
er b
odie
s, a
nd
2. C
an b
e co
mbi
ned
with
see
page
met
ers
to e
stim
ate
flux.
LIM
ITAT
ION
S
1. N
umer
ous
sour
ces
of e
rror
exi
st,
2. N
ot w
ell s
uite
d fo
r fas
t flow
ing
wat
ers
or s
urfa
ce
wat
er b
odie
s w
ith s
igni
fican
t wav
e ac
tion,
3. B
est s
uite
d fo
r use
as
a re
conn
aiss
ance
tool
.
Rose
nber
ry e
t al.,
(200
8).
Fibe
r opt
ic
dist
ribut
ed
tem
pera
ture
se
nsor
s
Fibe
r opt
ic te
mpe
ratu
re s
enso
rs a
re
depl
oyed
as
long
cab
les
alon
g th
e ba
se
of th
e riv
er o
r stre
am o
r oth
er s
urfa
ce
wat
er b
ody.
Con
tinuo
us te
mpe
ratu
re
mea
sure
men
ts a
long
the
leng
th o
f th
e ca
ble
can
be u
sed
to e
stim
ate
grou
ndw
ater
dis
char
ge, w
hich
ge
nera
lly h
as a
dis
tinct
tem
pera
ture
si
gnal
from
the
surf
ace
wat
er, i
nto
the
surf
ace
wat
er s
yste
m.
Fibe
r opt
ic te
mpe
ratu
re s
enso
r can
:
1. I
dent
ify g
aini
ng re
ache
s in
inte
rcon
nect
ed
syst
ems,
2. P
rovi
de b
asel
ine
info
rmat
ion
abou
t a g
iven
sys
tem
an
d ho
w it
cha
nges
thro
ugh
time.
BEN
EFIT
S
1. R
eal-t
ime,
hig
h re
solu
tion
data
col
lect
ion,
and
2. T
rack
s m
ovem
ent o
f gro
undw
ater
thro
ugh
a co
nnec
ted
syst
em in
com
bina
tion
with
oth
er
met
hods
.
LIM
ITAT
ION
S
1. D
eplo
ymen
t can
be
chal
leng
ing
depe
ndin
g on
the
natu
re o
f the
sys
tem
and
may
resu
lt in
dis
turb
ance
to
the
sedi
men
ts, a
nd
2. C
an b
e la
bor-
inte
nsiv
e to
inst
all.
Mw
akan
yam
ale
et a
l. (2
012)
.
Slat
er e
t al.
(201
0).
Ons
ite im
ager
yPh
otog
raph
s of
the
sam
e lo
catio
n ov
er
time
to tr
ack
chan
ges
in in
frast
ruct
ure,
ph
enol
ogy
of v
eget
atio
n as
a p
roxy
fo
r gro
undw
ater
, and
oth
er re
leva
nt
para
met
ers
at a
site
sca
le.
Ons
ite im
ager
y ca
n:
1. B
e us
ed to
gro
und-
truth
rem
ote
sens
ing-
base
d da
ta, a
nd
2. P
rovi
de b
asel
ine
info
rmat
ion
abou
t a g
iven
sys
tem
an
d ho
w it
cha
nges
thro
ugh
time
if ph
otos
are
ta
ken
at th
e sa
me
loca
tion
thro
ugh
time.
BEN
EFIT
S
1. S
impl
e an
d in
tuiti
ve fo
r man
y us
ers
sinc
e it
requ
ires
very
littl
e ex
pert
ise
to o
btai
n pi
ctur
es.
LIM
ITAT
ION
S
1. S
mal
l sca
le o
bser
vatio
n m
ay b
e di
fficu
lt to
ex
trapo
late
ove
r lar
ger a
reas
.
Tabl
e D3
(con
tinue
d)
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 20
Tool
s/M
etho
dsDe
scrip
tion
Appl
icat
ion/
Use
Case
Bene
fits/
Lim
itatio
nsCa
se S
tudi
es/K
ey R
efer
ence
s
Hand
held
ther
mal
im
agin
g ca
mer
asHa
ndhe
ld th
erm
al im
agin
g ca
mer
as
can
be u
sed
to im
age
stre
ams
and
lake
s an
d to
loca
te v
aria
tions
in
tem
pera
ture
. Thi
s in
form
atio
n ca
n th
en b
e us
ed to
trac
e gr
ound
wat
er
disc
harg
e in
to a
stre
am.
Ther
mal
imag
ing
cam
eras
can
:
1. H
elp
iden
tify
gain
ing
reac
hes
in in
terc
onne
cted
sy
stem
s,
2. B
e us
ed to
gro
und-
truth
rem
ote
sens
ing-
base
d da
ta,
3. O
ptim
ize th
e lo
catio
n of
mor
e in
volv
ed s
tudi
es o
f in
terc
onne
cted
sur
face
wat
er, a
nd
4. P
rovi
de b
asel
ine
info
rmat
ion
abou
t a g
iven
sys
tem
an
d ho
w it
cha
nges
thro
ugh
time
if ph
otos
are
ta
ken
at th
e sa
me
loca
tion
thro
ugh
time.
BEN
EFIT
S
1. Q
uick
dat
a co
llect
ion,
and
2. C
an b
e us
ed in
diffi
cult-
to-a
cces
s ar
eas.
LIM
ITAT
ION
S
1. B
est s
uite
d fo
r use
as
a re
conn
aiss
ance
tool
.
USG
S, H
ydro
geop
hysi
cs B
ranc
h.
Brig
gs e
t al.
(201
3).
In-s
itu s
oil o
r ve
geta
tion
surv
eys
Vege
tatio
n an
d so
il su
rvey
s ar
e ty
pica
lly c
ondu
cted
to c
hara
cter
ize
plan
t and
or s
oil t
ypes
in a
spe
cific
ar
ea (e
.g.,
a w
etla
nd o
r an
upla
nd a
t th
e si
te o
r stre
am re
ach
scal
e).
In-s
itu s
oil a
nd v
eget
atio
n su
rvey
s ca
n:
1. B
e us
ed to
iden
tify
and
char
acte
rize
ripar
ian
spec
ies
or h
abita
ts th
at m
ay b
e to
o fin
e fo
r oth
er
met
hods
to re
solv
e, a
nd
2. G
roun
d-tru
th re
mot
e-se
nsin
g da
ta.
BEN
EFIT
S
1. P
rovi
des
expl
icit
insi
ght i
nto
loca
l veg
etat
ion
and
soil
char
acte
ristic
s, a
nd
2. I
ncre
ases
con
fiden
ce in
rem
ote-
sens
ing
base
d m
etho
ds.
LIM
ITAT
ION
S
1. R
esou
rce
inte
nsiv
e,
2. S
ubje
ct to
sam
plin
g an
d hu
man
err
or.
Isot
opes
and
trac
ers
Stab
le a
nd
radi
oact
ive
isot
opes
Stab
le a
nd ra
dioa
ctiv
e is
otop
e co
mpa
res
the
uniq
ue is
otop
ic s
igna
ture
of
sam
pled
wat
er a
gain
st th
e un
ique
is
otop
ic s
igna
ture
s of
pre
cipi
tatio
n an
d an
y ad
jace
nt s
urfa
ce w
ater
sou
rces
to
dete
rmin
e th
e so
urce
of t
he s
ampl
ed
wat
er. I
n th
is w
ay, i
soto
pic
sign
atur
e ca
n al
so b
e us
ed to
trac
k flo
w d
irect
ion
at a
var
iety
of s
cale
s (e
.g. s
ite, s
tream
re
ach,
bas
in, a
nd re
gion
).
Stab
le a
nd ra
dioa
ctiv
e is
otop
es a
re n
eces
sary
/re
com
men
ded
for:
1. T
rack
ing
grou
ndw
ater
flow
rate
s, c
ontri
butio
ns,
and
sour
ce,
2. E
stab
lishi
ng a
site
-spe
cific
geo
chem
ical
bas
elin
e fo
r fur
ther
ana
lyse
s,
3. E
stab
lishi
ng s
ourc
e in
puts
for d
iffer
ent t
ypes
of
mod
els,
and
4. D
eter
min
ing
rela
tive
cont
ribut
ion
of d
iffer
ent
sour
ces
to b
asefl
ow, i
n co
mbi
natio
n w
ith o
ther
to
ols
(e.g
. stre
amflo
w g
agin
g)
BEN
EFIT
S
1. T
rack
s m
ovem
ent o
f gro
undw
ater
thro
ugh
a co
nnec
ted
syst
em in
com
bina
tion
with
oth
er
met
hods
.
LIM
ITAT
ION
S
1. P
ossi
ble
need
for m
ore
sign
ifica
nt ti
me
and
mon
ey
to c
aptu
re te
mpo
ral a
nd s
patia
l res
olut
ion.
USG
S, R
esou
rces
on
Isot
opes
.
Philli
ps. (
1995
).
Tabl
e D3
(con
tinue
d)
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 21
Tool
s/M
etho
dsDe
scrip
tion
Appl
icat
ion/
Use
Case
Bene
fits/
Lim
itatio
nsCa
se S
tudi
es/K
ey R
efer
ence
s
Trac
er te
sts
Trac
er te
sts
add
trace
rs (e
.g. d
yes
and
salts
) a w
ater
bod
y to
det
erm
ine
flow
ra
tes,
cha
ract
erize
flow
pat
hs, s
ourc
e an
d de
stin
atio
n, a
nd d
eter
min
e m
ixin
g ra
tes.
Trac
er te
sts
can:
1. P
rovi
de e
stim
ates
of fl
ow ra
te,
2. P
rovi
de in
sigh
t int
o flo
w p
athw
ays,
wat
er s
ourc
es
and
dest
inat
ion,
3. D
eter
min
e m
ixin
g ra
tes,
and
4. B
e co
mbi
ned
with
oth
er m
etho
ds to
pro
vide
es
timat
es o
f res
iden
ce ti
me
at a
var
iety
of s
cale
s.
BEN
EFIT
S
1. C
an p
rovi
de d
irect
est
imat
es o
f flow
rate
an
d de
gree
of c
onne
ctiv
ity in
inte
rcon
nect
ed
hydr
olog
ic s
yste
ms.
LIM
ITAT
ION
S
1. B
est u
sed
in a
sys
tem
with
fast
resp
onse
tim
es,
2. P
rope
r tra
cer p
repa
ratio
n is
ess
entia
l, an
d
3. T
race
r ana
lysi
s m
ust b
e co
mpa
red
agai
nst
base
line
cond
ition
s.
Tayl
or a
nd G
reen
e. (2
008)
.
Geop
hysi
cal m
easu
rem
ents
, rem
ote
sens
ing,
map
ping
, and
imag
ery
Rem
ote
sens
ing
of
vege
tatio
nRe
mot
e se
nsin
g br
oadl
y re
fers
to a
ny
data
col
lect
ion
tech
niqu
e th
at d
oes
not r
equi
re th
e us
er to
be
phys
ical
ly pr
esen
t. Fo
r int
erco
nnec
ted
surf
ace
wat
er, r
emot
e se
nsin
g ha
s pr
imar
ily
focu
sed
on m
appi
ng o
f sur
face
-bas
ed
indi
cato
rs li
ke v
eget
atio
n (s
ee m
appi
ng
grou
ndw
ater
dep
ende
nt e
cosy
stem
s be
low
). Su
rvey
s ca
n be
con
duct
ed
at a
var
iety
of s
cale
s an
d re
sulti
ng
reso
lutio
ns, i
nclu
ding
by
dron
e an
d ai
rbor
ne a
nd s
pace
-bas
ed s
atel
lites
.
Rem
ote
sens
ing
can:
1. H
elp
iden
tify
and
mon
itor i
mpa
cts
on g
roun
dwat
er
depe
nden
t veg
etat
ion,
and
2. P
rovi
de a
n es
timat
e of
pla
nt h
ealth
, whi
ch c
an
serv
e as
a p
roxy
for g
roun
dwat
er le
vels
.
BEN
EFIT
S
1. P
rovi
des
data
at a
var
iety
of s
cale
s, d
epen
ding
on
met
hods
use
d,
2. C
an b
e lo
w o
r hig
h-co
st, d
epen
ding
on
met
hods
us
ed, a
nd
3. S
atel
lite
data
can
pro
vide
s hi
stor
ical
dat
a in
som
e ca
ses.
LIM
ITAT
ION
S
1. C
an b
e di
fficu
lt to
inte
rpre
t and
requ
ires
grou
nd-
truth
ing,
and
2. S
patia
l and
tem
pora
l cov
erag
e m
ay b
e lim
ited
for
som
e sa
tellit
e da
ta.
Eam
us e
t al.
(201
5).
Pai e
t al.
(201
7).
Map
ping
of
grou
ndw
ater
de
pend
ent
ecos
yste
ms
Iden
tifica
tion
of g
roun
dwat
er
depe
nden
t eco
syst
ems
(GDE
s) c
an
be d
one
usin
g a
varie
ty o
f met
hods
, in
clud
ing
diur
nal g
roun
dwat
er le
vel
fluct
uatio
ns, i
soto
pic
anal
ysis
, rem
ote
sens
ing
data
, and
the
com
pila
tion
of
vege
tatio
n da
tase
ts w
ith lo
cal g
eolo
gy
and
grou
ndw
ater
dep
th. S
tate
wid
e m
appi
ng o
f GDE
s in
Cal
iforn
ia b
y Th
e Na
ture
Con
serv
ancy
was
don
e us
ing
latte
r met
hods
.
GDE
map
ping
can
:
1. T
o id
entif
y an
d m
onito
r are
as in
terc
onne
cted
su
rfac
e w
ater
and
gai
ning
and
losi
ng re
ache
s, a
nd
2. M
onito
r GDE
s ov
er ti
me.
BEN
EFIT
S
1. P
rovi
des
a fir
st-o
rder
est
imat
e of
GDE
loca
tions
ac
ross
the
stat
e.
LIM
ITAT
ION
S
1. R
equi
re g
roun
dtru
thin
g an
d su
pple
men
tal
anal
ysis
via
veg
etat
ion
and
faun
a su
rvey
s or
oth
er
met
hods
.
TNC,
The
Gro
undw
ater
Res
ourc
e Hu
b.
Rohd
e et
al.
(201
7).
Klau
smey
er e
t al.
(201
0).
Tabl
e D3
(con
tinue
d)
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 22
Tool
s/M
etho
dsDe
scrip
tion
Appl
icat
ion/
Use
Case
Bene
fits/
Lim
itatio
nsCa
se S
tudi
es/K
ey R
efer
ence
s
Elec
trica
l Res
istiv
ityEl
ectri
cal r
esis
tivity
is a
tech
nolo
gy th
at
uses
ele
ctro
mag
netic
pro
pert
ies
of th
e so
il to
map
out
sub
surf
ace
elec
trica
l pr
oper
ties,
whi
ch c
an b
e in
terp
rete
d to
gi
ve g
eolo
gy a
nd s
ubsu
rfac
e st
ruct
ure.
Elec
trica
l res
istiv
ity c
an:
1. E
stim
ate
dept
h to
the
wat
er ta
ble,
2. I
mag
e th
e sa
lt an
d fre
shw
ater
inte
rfac
e,
3. P
rovi
de in
sigh
t int
o th
e de
gree
of c
onne
ctiv
ity
betw
een
surf
ace
wat
er a
nd g
roun
dwat
er s
yste
ms,
an
d
4. B
e co
mbi
ned
with
lith
olog
ical
, phy
sioc
hem
ical
, an
d ge
olog
ical
info
rmat
ion
to d
evel
op a
det
aile
d hy
drog
eolo
gica
l mod
el.
BEN
EFIT
S
1. P
rovi
des
non-
inva
sive
imag
es o
f the
sub
surf
ace.
LIM
ITAT
ION
S
1. R
equi
res
litho
logi
cal r
ecor
ds fr
om b
oreh
oles
for
inte
rpre
tatio
n,
2. R
equi
res
expe
rtis
e to
inte
rpre
t res
ults
, and
3. I
t can
be
diffi
cult
to d
iffer
entia
te c
hang
es
in li
thol
ogy
with
cha
nges
in m
oist
ure
valu
es
part
icul
arly
in a
reas
with
bra
ckis
h or
sal
ine
wat
er.
USG
S, H
ydro
geop
hysi
cs B
ranc
h.
Card
enas
and
Mar
kow
ski.
(201
1).
Mw
akan
yam
ale
et a
l. (2
012)
.
Syst
em-b
ased
app
roac
hes
Wat
er B
alan
ceA
wat
er b
alan
ce is
an
acco
untin
g of
al
l infl
ows
and
outfl
ows
of w
ater
in
a sy
stem
. Key
com
pone
nts
of th
e w
ater
bal
ance
(e.g
. gro
undw
ater
co
ntrib
utio
n, s
tora
ge, e
tc.)
can
be
isol
ated
for f
urth
er a
naly
sis.
Wat
er b
alan
ces
can:
1. P
rovi
de in
sigh
t int
o th
e do
min
ant h
ydro
logi
c pr
oces
ses
influ
enci
ng a
sys
tem
(e.g
., su
rfac
e w
ater
con
tribu
tions
, gro
undw
ater
pum
ping
, re
char
ge),
2. P
rovi
de in
sigh
t int
o th
e im
pact
s of
pro
ject
, clim
ate
chan
ge a
nd h
uman
impa
cts
whe
n ca
lcul
ated
and
co
mpa
red
thro
ugh
time,
3. H
elp
iden
tify
area
s of
unc
erta
inty
in th
e sy
stem
,
4. H
elp
to a
sses
s sp
atia
l and
tem
pora
l gro
undw
ater
-su
rfac
e w
ater
flow
dyn
amic
s; a
nd
5. A
ssis
t in
dete
rmin
ing
grou
ndw
ater
con
tribu
tion
(via
the
bala
nce
of in
puts
and
out
puts
) and
gai
ning
an
d lo
sing
reac
hes
in a
sys
tem
.
BEN
EFIT
S
1. R
elat
ivel
y si
mpl
e an
d lo
w c
ost,
but t
he c
ompl
exity
of
eac
h w
ater
bud
get c
an v
ary
subs
tant
ially
.
LIM
ITAT
ION
S
1. M
ay n
ot p
rovi
de a
full
pict
ure
of c
ompl
ex
grou
ndw
ater
dyn
amic
s, a
nd
2. R
elie
s up
on a
ccur
ate
wat
er b
alan
ce d
ata,
whi
ch
may
be
limite
d.
Heal
y et
al.
(200
7).
Ruud
et a
l. (2
004)
.
Tabl
e D3
(con
tinue
d)
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 23
Tool
s/M
etho
dsDe
scrip
tion
Appl
icat
ion/
Use
Case
Bene
fits/
Lim
itatio
nsCa
se S
tudi
es/K
ey R
efer
ence
s
Anal
ytic
al M
odel
sAn
alyt
ical
mod
els
rely
on s
igni
fican
t si
mpl
ifica
tions
of t
he s
yste
m (e
.g.,
linea
r stre
ams
of in
finite
leng
th,
fully
pen
etra
ting
stre
ambe
ds,
hom
ogen
ous
aqui
fers
, a s
ingl
e w
ell)
to
mat
hem
atic
ally
solv
e th
e gr
ound
wat
er
flow
equ
atio
n. T
hese
mod
els
are
rela
tivel
y si
mpl
e to
run
and
prov
ide
a go
od in
itial
est
imat
e of
a s
yste
m a
t the
re
ach
or b
asin
sca
le. M
ore
com
plex
an
alyt
ical
mod
els
have
bee
n de
velo
ped
for s
emi-c
onfin
ed a
nd la
yere
d aq
uife
rs,
part
ially
pen
etra
ting
stre
ambe
ds, a
nd
mul
tiple
wel
ls.
Anal
ytic
al m
odel
s ca
n:
1. P
rovi
de in
sigh
t int
o do
min
ant h
ydro
logi
c pr
oces
s go
vern
ing
a sy
stem
,
2. P
rovi
de a
goo
d in
itial
est
imat
e of
pum
ping
impa
cts
on s
tream
flow
, and
3. B
e de
velo
ped
in a
reas
with
lim
ited
data
and
re
sour
ces.
BEN
EFIT
S
1. A
llow
s fo
r bas
ic m
odel
ing
of s
tream
dep
letio
n,
2. S
impl
er a
nd lo
wer
cos
t tha
n a
num
eric
al m
odel
,
3. P
rovi
des
good
wor
king
kno
wle
dge
of tr
ends
and
ov
eral
l im
pact
s, a
nd
4. C
an b
e de
velo
ped
with
lim
ited
data
.
LIM
ITAT
ION
S
1. R
equi
res
sign
ifica
nt s
impl
ifyin
g as
sum
ptio
ns th
at
limit
pred
ictiv
e ca
pabi
litie
s, a
nd
2. B
est s
uite
d fo
r min
imal
ly de
velo
ped
syst
ems
or
syst
ems
with
lim
ited
data
or r
esou
rces
.
Oki
and
Mey
er. (
2001
).
Hugg
ins
et a
l. (2
018)
.
Num
eric
al M
odel
sNu
mer
ical
mod
els
are
com
pute
r m
odel
s of
a g
roun
dwat
er s
yste
m o
r in
tegr
ated
hyd
rolo
gic
syst
em th
at
allo
w fo
r irr
egul
ar g
roun
dwat
er b
asin
bo
unda
ries,
irre
gula
r stre
am o
r riv
er
geom
etry
, com
plex
pum
ping
sch
edul
es
at m
ultip
le w
ells
, and
cha
ngin
g bo
unda
ry c
ondi
tions
. Sim
ulat
ed re
sults
ca
n be
use
d to
ana
lyze
diff
eren
t m
anag
emen
t sce
nario
s as
wel
l as
test
hy
poth
eses
at t
he s
tream
reac
h, b
asin
, an
d re
gion
sca
le.
Num
eric
al m
odes
can
:
1. P
rovi
de in
sigh
t int
o do
min
ant p
roce
ss g
over
ning
a
syst
em,
2. B
e us
ed to
iden
tify
gain
ing
and
losi
ng re
ache
s in
a
syst
em a
nd m
odel
cha
nges
thro
ugh
time,
and
3. S
imul
ate
chan
ges
to th
e sy
stem
resu
lting
from
pr
ojec
ts (e
.g.,
rech
arge
bas
ins)
, lan
d us
e, c
limat
e ch
ange
or o
ther
fact
ors,
whe
n w
ell c
alib
rate
d.
BEN
EFIT
S
1. P
rovi
des
for t
he s
imul
atio
n an
d pr
edic
tion
of
the
mod
eled
sys
tem
, inc
ludi
ng c
hang
es in
in
terc
onne
cted
sur
face
wat
ers,
and
2. A
ccou
nts
for t
hree
-dim
ensi
onal
com
plex
ity o
f gr
ound
wat
er s
yste
m.
LIM
ITAT
ION
S
1. A
ccur
acy
depe
nds
on q
ualit
y of
inpu
t dat
a,
2. R
equi
res
high
qua
lity
data
with
a lo
ng re
cord
for
pred
ictiv
e ca
pabi
litie
s, a
nd
3. C
an b
e ex
pens
ive
and
labo
r int
ensi
ve to
dev
elop
an
d m
aint
ain.
Barlo
w a
nd L
eake
. (20
12).
Mor
an (2
016)
.
Flec
kens
tein
et a
l. (2
006)
.
Resp
onse
Fun
ctio
ns
and
Capt
ure
Map
sAn
alyt
ical
and
num
eric
al m
odel
s ca
n ge
nera
te s
tream
flow
-dep
letio
n re
spon
se fu
nctio
ns a
nd c
aptu
re m
aps,
w
hich
cha
ract
erize
the
rela
tions
hip
betw
een
loca
lized
pum
ping
in a
n aq
uife
r and
nea
rby
stre
am d
eple
tion.
Resp
onse
func
tions
and
cap
ture
map
s ca
n:
1. P
rovi
de in
sigh
t int
o ho
w a
stre
am o
r stre
am re
ach
is li
kely
to re
spon
d to
pum
ping
at a
par
ticul
ar
wel
l.
BEN
EFIT
S
1. P
rovi
de in
sigh
ts in
to th
e re
latio
nshi
p be
twee
n gr
ound
wat
er p
umpi
ng a
nd s
tream
flow
that
may
be
diffi
cult
to a
chie
ve v
ia m
onito
ring.
LIM
ITAT
ION
S
1. A
ccur
acy
depe
nds
upon
qua
lity
of in
put d
ata
and
mod
el c
alib
ratio
n, a
nd
2. D
ifficu
lty in
sep
arat
ing
depl
etio
n ch
ange
s fro
m
stre
amflo
w re
spon
ses
to o
ther
cha
nges
(e.g
., cl
imat
e, s
urfa
ce w
ater
div
ersi
ons
upst
ream
).
Barlo
w a
nd L
eake
. (20
12).
Fogl
ia, L
., et
al.
(201
3).
Tabl
e D3
(con
tinue
d)
WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 24
Table D3. References
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Briggs, M.A., Voytek, E.B., Day-Lewis, F.D, Rosenberry, D.O., and Lane, J.W. (2013). The hydrodynamic controls on thermal refugia for endangered mussels in the Delaware River. Environmental Sciences and Technology, 47(20):11423-11431. doi:10.1021/es4018893.
Cardenas, M.B. and M. S. Markowski. (2011). Geoelectrical imaging of hyporheic exchange and mixing of river water and groundwater in a large regulated river. Environmental Science & Technology, 45(4): 1407-1411. doi: 10.1021/es103438a.
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WATER IN THE WEST Tools for Assessing Groundwater-Surface Water Connectivity Under the Sustainable Groundwater Management Act 26
For more information visit:waterinthewest.stanford.edu
Water in the WestStanford UniversityJerry Yang & Akiko Yamazaki Environment& Energy Building473 Via Ortega, MC 4205Stanford, CA [email protected]