ExeTo: Board of Directors of the Sonoma County Water Agency
Department or Agency Name(s): Sonoma County Water Agency
Staff Name and Phone Number: Dale Roberts, 707-547-1979
Vote Requirement: Majority
Supervisorial District(s): Countywide
Title:
Title
Sonoma Water Climate Adaptation Plan
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Recommended Action:
Recommended action
Approve Sonoma County Water Agency’s Climate Adaptation Plan
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Executive Summary:
The Sonoma County Water Agency’s (Sonoma Water) Climate Adaptation Plan (Plan) serves as a roadmap for Sonoma Water to follow by providing strategies to reduce climate-risk impacts to its infrastructure and operations. The Plan will enhance Sonoma Water’s ability to meet the public health and safety needs of the community through Sonoma Water’s water supply, flood-risk management, and sanitation core functions. In addition, the plan aligns with the County’s Strategic Plan Climate Action and Resiliency and Resilient Infrastructure pillars.
The Plan identifies threats to Sonoma Water’s water supply, flood control, and sanitation infrastructure and operations and develops adaptation strategies to reduce vulnerabilities and risks exacerbated by climate change. Some of the risks are specific to Sonoma Water infrastructure and operations, while other risks to Sonoma Water’s operations involve broader watershed impacts that affect the community and thus require partnerships to address. The plan also includes anchor adaptation strategies for each of Sonoma Water’s core functions of water supply, flood control, and sanitation.
Approving the Plan will strategically and proactively position Sonoma Water to pursue climate adaptation funding from state and federal agencies and to pursue collaborations with other local and regional entities to adapt to the current and future impacts of climate change to our core functions. This would allow Sonoma Water to continue to provide water supply, flood control, and sanitation services essential for the health and safety of the community.
Discussion:
Over the past decade, Sonoma Water has partnered with the U.S. Geological Survey, the National Oceanic and Atmospheric Administration, Scripps Institute of Oceanography Center for Western Weather and Water Extremes, Sonoma County Regional Climate Protection Authority, the North Bay Climate Adaptation Initiative, and other entities to understand the scientific advances related to weather and climate research and to evaluate the potential impacts of climate change and to assess climate risk and impacts to regional water resources.
These studies indicate that water resources in Sonoma County will experience the effects of climate change through increased temperatures and variability of precipitation resulting in more extreme droughts and floods. In addition, sea level rise and increased wildfire intensity are other important climate-risk impacts. Each of these climate-risk impacts will affect Sonoma Water’s infrastructure and operations. To assure that Sonoma Water is prepared to continue providing services to protect the health and safety of Sonoma County residents, staff contracted with Jacobs (formerly CH2MHill) in a professional services agreement approved by the Board on July 19, 2016 to develop a Climate Adaptation Plan (Plan) that addresses Sonoma Water’s operations and planning for future projects and needed infrastructure upgrades or improvements.
Jacobs and Sonoma Water staff, in collaboration with local and regional stakeholders, developed the Plan, which includes the following elements:
1. Executive Summary: High-level summary of the key content and main findings of the report.
2. Introduction: Brief description of the climate change challenges and the purpose of the report.
3. Climate Adaptation Planning: Overview of Plan Framework including: 1) Problem Scoping, 2) Hazard Understanding and Mapping, 3) Vulnerability and Risk Assessments, 4) Adaptation Strategy Development, and 5) Implementation and Monitoring.
4. Sonoma Water System Descriptions: Description of the core functions of Sonoma Water’s water supply, flood control , and sanitation systems and summary of related facilities.
5. Climate and Hydrology Science: Overview of Sonoma Water’s climate science collaborations specifically evaluating forecasted climate impacts for the North Bay region. These activities, in conjunction with other international, national, and statewide analyses, indicate the following potential future climate-related risks to Sonoma County:
a. Continuing increasing temperatures are consistently predicted by climate projection models.
b. Although the climate projection models do not agree whether Sonoma County will be overall wetter or drier in the future, there is agreement that precipitation will be more variable and that Atmospheric Rivers (ARs) are likely to play an increasingly significant role in that variability.
c. Sea-level rise will continue to occur.
d. Given increasing temperature and variability of precipitation, the severity of droughts is likely to increase.
e. Stronger flooding events are considered likely due to increased variability of precipitation and increased role and strength of ARs.
f. An increased risk of wildfires is predicted across the Western United States, including Sonoma County.
6. Vulnerability Assessment: Approach and findings of vulnerability assessment of Sonoma Water’s core functions based on assessing the “sensitivity” of assets or operation of those assets to each climate threat and the existing “adaptive capacity” of these systems to accommodate the anticipated changes from climate threats. Vulnerability is a function of an asset’s sensitivity and adaptive capacity. Climate threats to Sonoma Water’s water supply, flood management, and sanitation systems were comprehensively assessed. Climate change maps were developed; water supply and flood modeling was conducted on the Russian River and Santa Rosa Creek; and major facilities were visited and studied to assess vulnerabilities to future climate change. Vulnerability and risk assessments were conducted for all major components of the systems. Major areas of risk identified in the Climate Adaptation Plan include:
Water Supply - River flooding and wildfire risk at Mirabel and Wohler diversion facilities; river flooding and extreme precipitation risk at River Road and Wohler chlorination facilities; and extreme precipitation risk at Ely Booster and Kawana Boosters.
Flood Management - Extreme precipitation, river flooding and wildfire risk at Central Sonoma Watershed Project infrastructure; sea level rise and river flooding risk on the Petaluma River and on Sonoma Creek; river flooding risk on the upper Russian River; and sea level rise and river flooding risk on the lower Russian River and estuary.
Sanitation - Extreme precipitation, river flooding, and sea level rise risks at wastewater treatment plants, collection systems, and reclamation systems.
7. Risk Assessment: Assessment of the risk of those systems to climate threats based on the vulnerabilities of systems which is a function of the consequence of the threat and the likelihood of the threat.
8. Adaptation Strategy Development. Ranking of the risks to Sonoma Water’s assets as Low, Medium, or High based on 25-, 50-, and 75-year planning horizons. Description of adaptation strategies developed based on those risks based on input through numerous staff workshops involving all Sonoma Water divisions.
9. Adaptation Strategy Recommendations and Implementation: Description of portfolios of strategic adaptation actions for each core function that were developed from the workshop. Some of the adaptation strategies benefit more than one core function and these strategies are combined into Integrated Strategies, such as Forecast Informed Reservoir Operations which benefits water supply and flood risk management. Strategies were prioritized based on an evaluation that considered specific criteria. Criteria includes the cost of inaction, expected performance of recommended strategies, strategy benefits, implementation feasibility, funding potential, organizational alignment, timing, certainty, etc. Next steps for implementation are included in this section.
Anchor adaptation strategies for each of Sonoma Water’s core functions of water supply, flood control, and sanitation are as follows:
Water Supply Anchor Adaptation Strategies
The recommended water supply adaptation portfolio consists of eight anchor projects that are believed to best put Sonoma Water on a path for adapting to climate change. These anchor projects are listed and briefly described below.
• Water Diversion Facilities Protection Program - Integration of multiple project concepts that seek to protect Wohler and Mirabel diversion infrastructure and to allow access during flood and wildfires. These include retrofitting collectors with submarine-type doors to seal from water entry during potential high flood events, elevating levee roads at Mirabel collectors, and elevating and strengthening Collector 6 to prioritize operation of this collector even under higher anticipated flood water levels.
• Alternative Russian River Water Treatment - This project involves a study and development of a new, robust drinking water treatment facility on the Russian River to offer alternative water treatment should post-fire water quality temporarily render the chlorination disinfection system ineffective to treat to Clean Drinking Water standards.
• Forecast-Informed Reservoir Operations (FIRO)- This project includes the consolidation of FIRO efforts related to Lake Mendocino, Lake Sonoma, and flood control structures into a combined program. Incorporating into a program would allow the science, data, tools, and policies to have greater impact and operational capability.
• Regional Water Supply Strategies - This project concept continues to invest in regional water resiliency strategies and the Water Supply Action Plan strategies to facilitate diversification of supplies and demands during changed conditions and reduce regional risks. Use the Regional Water Supply Resiliency Study to identify and develop integrated water supply strategies into a seasonal, annual, or interannual storage program (groundwater banking, source-shifting program, or transmission storage).
• Watershed Resilience Program - Integrate multiple concepts that focus on healthy headwaters, hydrologic and sediment management, land and vegetation management for flood attenuation, and water quality benefits during extreme hydrologic events after wildfire events. This program would integrate strategic studies with specific watershed management activities under a watershed resilience program to promote and fund beneficial watershed activities both within and outside of Sonoma Water’s immediate jurisdiction. This program would provide substantial benefits for all Sonoma Water systems.
• Increasing Stormwater Detention and Recharge - These projects protect against growing flood risk by enhancing detention, infiltration, and groundwater recharge. Studies would identify areas of flooding and areas of higher recharge potential. Detention ponds or enhanced recharge areas would be constructed in strategic areas. Concept would fall into the broad domain of Flood Managed Aquifer Recharge (Flood-MAR) projects being supported by California Department of Water Resources. Elements could be constructed new or managed through easements with existing landholders.
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• Hydroclimate Program - Integrate multiple, related efforts of climate, weather, and hydrological measurement, data assimilation, prediction and modeling into a program to more effectively support Sonoma Water as a whole. The program would consolidate these efforts and operationalize application to support specific needs in the water supply, flood management, and sanitation systems.
Flood Management Anchor Adaptation Strategies
The recommended flood management adaptation portfolio consists of seven anchor projects that are believed to best put Sonoma Water on a path for adapting to climate change. These anchor projects are listed and briefly described below.
• Regional Flood Management Strategy - This project seeks to address the current lack of a regional flood management strategy. Review of existing flood plans has revealed that due to disjointed jurisdictional responsibilities within the watersheds a lack of an integrated regional flood management strategy that outlines specific goals and metrics for flood protection, common approaches for flood risk reduction, regional and local policies, and investment strategies. This project includes the development of a regional flood management strategy that would integrate planning, modeling, and management approaches for the Central Sonoma, Russian River, Laguna, and Estuary into a common flood management framework and plan.
• Sediment Source Study - Future changes in precipitation and flood flows will substantial increase sediment loading in the region's watersheds. This project will identify major sources of sediment with each watershed and quantify historical and future sediment loads using the modeling. The study would identify sediment source "hot spots" and recommend strategies for source control. Programmatic permits would be updated for increases in sediment.
• Central Sonoma Watershed Project Vulnerability Assessment - Due to the significant flood-related risks associated with facilities and operations of the Central Sonoma Watershed Project, a focused vulnerability assessment is proposed. Initially, this project could leverage current funding and study by Natural Resources Conservation Service and Sonoma Water.This effort would ultimately encompass the entire watershed and include outreach and engagement with major stakeholders and landowners in the city of Santa Rosa and along Santa Rosa Creek, Mark West Creek, and the Laguna.
• Forecast-Informed Reservoir Operations - This project includes the consolidation of FIRO efforts related to Lake Mendocino, Lake Sonoma, and flood control structures into a combined program. Incorporating into a program would allow the science, data, tools, and policies to have greater impact and operational capability.
• Watershed Resilience Program - Integrate multiple concepts that focus on healthy headwaters, hydrologic and sediment management, land and vegetation management for flood attenuation, and water quality benefits during extreme hydrologic events after wildfire events. This program would integrate strategic studies with specific watershed management activities under a watershed resilience program to promote and fund beneficial watershed activities both within and outside of Sonoma Water’s immediate jurisdiction. This program would provide substantial benefits for all Sonoma Water systems.
• Flood-MAR Pilots - This project includes the implementation of three Flood-MAR type pilot projects in four flood zones: Laguna-Mark West watershed, the Sonoma Valley watershed, the Alexander Valley, and the Upper Petaluma River watershed. These pilot projects would implement strategies for recharging groundwater aquifers with excess flood waters, simultaneously lowering the risk of flooded communities while improving stressed groundwater resources.
• Hydroclimate Program - Integrate multiple, related efforts of climate, weather, and hydrological measurement, data assimilation, prediction and modeling into a program to more effectively support Sonoma Water as a whole. The program would consolidate these efforts and operationalize application to support specific needs in the water supply, flood management, and sanitation systems.
Sanitation System Anchor Adaptation Strategies
The recommended sanitation adaptation portfolio consists of eight anchor projects that are believed to best put Sonoma Water on a path for adapting to climate change. These anchor projects are listed and briefly described below.
• Infiltration/Inflow (I/I) Monitoring and Reduction Program - Many of the sanitation zone collection systems, but most acutely the Sonoma Valley and Russian River collection systems, suffer from high I/I during storm events which can also result in Sanitary Sewer Overflows [need to write out I/I and SSO]. The relatively poor understanding of these flows and the likelihood that future climate change will increase I/I in these systems requires focused effort. This project concept would establish an I/I Monitoring and Reduction program that would seek to (1) better understand areas of systems that have large I/I contributions, (2) implement a monitoring system on critical collection system segments in Sonoma Valley and Russian River, and (3) implement asset management program to upgrade sewer capacity and strategically replace aging sewer lines.
• Revised Collection System Design Standards - This project includes a review of the design standards and recommend revisions to further reduce I/I through improved design/construction practices and consideration of higher frequency and magnitude of rainfall during storm events associated with climate change. This project would be integrated with revisions to the flood management design criteria to include projected changes in timing, frequency, and duration of extreme precipitation under future climate scenarios.
• Eliminate Sonoma Valley Wastewater Treatment Plant Constraints due to Sea Level Rise - During the wet season (November 1-April 30), treated wastewater is discharged to Schell Slough, a tidally-influenced waterbody downstream of Schell Creek. During the dry season, tertiary treated effluent is discharged to Wetland Management Units 1 and 3 to maintain freshwater marshlands and ponds for wetland habitat enhancement. Between May 1 and October 31, treated wastewater is also used for irrigation of dairy fodder crops and vineyards. Sea level rise will effectively reduce the hydraulic capacity of effluent discharge and recycled water delivery due to more frequent tide gate closure and increasing hydraulic constraint. This project would increase the operational effluent pumping capacity and increase equalization storage capacity for increased sea level rise.
• Expand Sonoma Valley Reuse - Sonoma Valley wastewater treatment plant generates more treated wastewater in wet years than it currently has demand. Future climate change will likely exacerbate water supply challenges and increase saltwater intrusion in the Sonoma Valley groundwater basin. This project includes the expansion of partnerships with wineries and other irrigators, groundwater management entities, and regional entities such as Bay Area Clean Water Association and Solano Land Trust to increase the service area for recycled water. Opportunities exist for increased delivery for seawater intrusion barrier, irrigation customers near the current delivery system, and connection of additional customers and storage projects such as those in the North Bay Water Reuse Program.
• Identify Reuse Opportunities for all Sanitation Zones - While the emphasis should be appropriately placed on Sonoma Valley Reuse, opportunities exist for increased reuse opportunities in most sanitation zones. This project would investigate, summarize, and work towards expansion of reuse in other zones.
• Dynamic and Resilient Supervisory Control and Data Acquisition (SCADA) - This project concept builds on the Phase 1 SCADA Master Plan and implements automation pilots at Sonoma Valley and Russian River wastewater treatment plants based on the criticality of the systems and a priority list developed by operations staff. Most of the wastewater treatment plants have minimal automation and operations staff must manually make changes. Access to some of these facilities can be challenged during high flood events or fires which will be exacerbated by future climate change. Increased automation and redundant control capabilities are targeted.
• Improve Standard Operating Procedures (SOP) Development and Training - With projections of future climate change to indicating increased frequency and magnitude of extreme precipitation events, collection system I/I is expected to increase. This project seeks to reduce these flows through improved SOP development, training, and application. SOPs outline the procedures for on-going operations, maintenance, and testing (e.g., lateral inspection and smoke testing) of the collection systems to reduce the potential for SSOs. SOPs would be revised, and training initiated for all sanitation operations staff.
• Establish Sanitation Level Planning - Many of the sanitation systems that are currently managed by Sonoma Water were conceived and built by other entities in isolation. A regional and consistent system-wide assessment of sanitation needs, assets, and strategies has not been developed. No strategic planning level document such as the Water Supply Strategies Action Plan exists for the sanitation sector reflecting a differing approach. This project would establish a Strategic Sanitation Systems Plan (or similar) that would compile the state of each sanitation system, outline risks and opportunities to these systems, and perhaps identify regional solutions that could reduce risks, identify potential consolidation opportunities (e.g., Occidental and Airport).
Some common, integrated concepts have been identified across all three Sonoma Water core function portfolios that will likely provide the largest improvements in climate resiliency:
1) Watershed Resilience Program
2) Water Diversion Facilities Protection Program
3) Regional Water Supply Strategies
4) Forecast-Informed Operations
5) Regional Flood Management Strategy
6) Hydroclimate Program
7) Dynamic and Resilient Supervisory Control and Data Acquisition (SCADA) System
8) Integrated Sanitation Level Planning
Appendices
The Plan identifies threats to Sonoma Water’s water supply, flood control, and sanitation infrastructure and operations and develops adaptation strategies to reduce vulnerabilities and risks exacerbated by climate change. Some of the risks are specific to Sonoma Water infrastructure and operations, while other risks involve broader watershed impacts that affect the community. Adaptation strategies for infrastructure and operations include modifying operations of reservoir releases based on meteorological forecasting, which is currently being implemented in the (FIRO program for Lake Mendocino and with an initiation of FIRO viability soon to be commenced for Lake Sonoma. Adaptation strategies to address broader watershed impacts such as risk of wildfire, include collaborating with fire districts, emergency management departments, resource conservations districts, non-governmental organizations, Sonoma County Agricultural Preservation and Open Space District, and others on activities such as vegetation management programs, prescribed burn programs, and fire camera deployment. These programs help Sonoma Water adapt to threats that impact water quality, flood control infrastructure, sediment loadings, and water quality and supply, yet also have intrinsic benefits to these other partners and the community.
The Plan proactively and strategically positions Sonoma Water to be able to pursue climate adaptation funding from state and federal agencies, aligning our climate adaptation strategies with Governor’s climate goals, executive orders, and federal policy. State and federal agencies are increasingly requiring local agencies to include climate adaptation analyses and strategies in local hazard mitigation plans and other plans to be eligible for funding. Approving the Plan would put Sonoma Water in a stronger position to pursue outside funding and leverage our local investments.
Prior Board Actions:
10/20/20: Authorize General Manager to execute the Fourth Amended Agreement for Climate Adaptation Plan Preparation with CH2MHill to add additional modeling of floods, sediment loading, fire risk, and water quality necessary to better inform the adaptation strategies and actions.
08/30/16: Authorize General Manager, acting on behalf of Water Agency and County Sanitation Districts, to execute an agreement with CH2M Hill to prepare a Climate Adaptation Plan.
06/24/14: Authorize Chair to execute an agreement with CH2M HILL to provide prepare a Work Plan to prepare a Climate Adaptation Plan.
11/05/13: Direct the General Manager to return to the Board of Directors with a Work Plan to conduct a Vulnerability Assessment and prepare a Climate Change Adaptation Plan.
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Attachments:
Sonoma Water Climate Adaptation Plan - Executive Summary
Related Items “On File” with the Clerk of the Board:
Sonoma Water Climate Adaptation Plan