To: Board of Directors, Sonoma Valley County Sanitation District
Department or Agency Name(s): Sonoma Valley County Sanitation District
Staff Name and Phone Number: Brad Sherwood 707-547-1927, Alex Bodulow 707-521-1823
Vote Requirement: Majority
Supervisorial District(s): First
Title:
Title
Dam Inundation Analysis for Sonoma Valley County Sanitation District R4 and R5 Reclamation Reservoirs
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Recommended Action:
Recommended action
Authorize Sonoma County Water Agency’s General Manager acting on behalf of Sonoma Valley County Sanitation District to execute the First Amended and Restated Agreement for Dam Inundation Analysis for Sonoma Valley County Sanitation District R4 and R5 Reclamation Reservoirs with Dudek, in substantially the form as the draft presented to this Board. The amended agreement increases the amount by $50,000, extends the term by approximately six months, and expands the scope of work to include additional tasks for R5 reservoir inundation analysis and R4 and R5 reservoir mapping, for a new not-to-exceed Agreement total of $100,000 new term end date of June 30, 2027.
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Executive Summary:
In accordance with the California Water Code, the California Department of Water Resources (DWR), Division of Safety of Dams (DSOD) jurisdiction requires Sonoma Valley County Sanitation District (District) perform dam failure inundation modeling and mapping and dam inundation studies for its R4 and R5 reclamation reservoirs.
Discussion:
HISTORY OF ITEM/BACKGROUND
Sonoma County Water Agency operates and manages District under contract with District. References to District employees are understood to be Sonoma County Water Agency employees acting on behalf of District. District’s R4 and R5 reclamation reservoirs serve as effluent storage ponds for District’s treated recycled water and are critical to District’s infrastructure.
Under Section 6025.5 of the California Water Code, a dam may be exempt from State jurisdiction if it meets three criteria: 1) The facility's primary use must be wastewater treatment and storage; 2) The city governing body must adopt a resolution affirming the ponds were built and operated to standards that protect life and property, and must oversee their design, construction, enlargement, replacement, and removal; and 3) The dams must be no taller than 15 feet and have a capacity of 1,500 acre-feet or less.
On July 8, 2025, DSOD inspected the R4 and R5 reclamation reservoirs and deemed the R4 reclamation reservoir of significant hazard classification and the R5 reclamation reservoir of high hazard classification. As a result, DSOD requires District perform dam failure inundation modeling and mapping and dam inundation studies for both reservoirs.
District and Dudek (Consultant) entered into an agreement for dam inundation analysis, dated July 1, 2026, in the amount of $50,000. The analysis is underway, but additional funds and time are required for Consultant to complete the DSOD-required inundation study and mapping on the R4 and R5 reclamation reservoirs before the December 31, 2026 deadline. The additional scope ensures that both R4 & R5 will undergo a Dam Inundation Analysis.
SELECTION PROCESS
Consultant was selected through a competitive selection process conducted under the original agreement. A new competitive selection process was not conducted because this amended agreement covers additions to work already in progress, not a new scope of services.
SERVICES TO BE PERFORMED
Under the proposed amended agreement, Consultant will continue to perform dam inundation analysis and mapping for the R4 and R5 reclamation reservoirs in accordance with the California Water Code.
Additional funds are needed for Consultant to complete work required by the DSOD for inundation studies and mapping on the R4 and R5 reservoirs.
The additional cost is $50,000, for a new not-to-exceed agreement total of $100,000. The new end date is June 30, 2027.
Through the proposed amended agreement, the General Manager will be delegated the authority to approve a written amendment to extend the term of the agreement for up to two additional years by providing written notice to the other party thirty days in advance of the term end date and by executing an agreement amendment.
County of Sonoma Strategic Plan Alignment:
N/A
Sonoma Water Strategic Plan Alignment
Goal: Implement comprehensive, integrated, and innovative infrastructure planning to strengthen existing services, minimize life cycle costs, and prepare for the future.
Strategy: Develop processes for addressing emergency or urgent infrastructure repairs.
Work performed under the proposed amended agreement will strengthen the existing R4 and R5 reclamation reservoirs, ensuring safe functioning of this important wastewater infrastructure in the future.
Racial Equity:
Was this item identified as an opportunity to apply the Racial Equity Toolkit?
No
Prior Board Actions:
None.
Fiscal Summary
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Expenditures |
FY26-27 Adopted |
FY27-28 Projected |
FY28-29 Projected |
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Budgeted Expenses |
$50,000 |
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Additional Appropriation Requested |
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Total Expenditures |
$50,000 |
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Funding Sources |
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General Fund/WA GF |
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State/Federal |
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Fees/Other |
$50,000 |
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Use of Fund Balance |
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General Fund Contingencies |
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Total Sources |
$50,000 |
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Narrative Explanation of Fiscal Impacts:
Budgeted amount of $50,000 is available from FY 2026/2027 appropriations for the Sonoma Valley County Sanitation District Operations fund. No additional appropriation is required.
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Staffing Impacts: |
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Position Title (Payroll Classification) |
Monthly Salary Range (A-I Step) |
Additions (Number) |
Deletions (Number) |
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Narrative Explanation of Staffing Impacts (If Required):
N/A
Attachments:
Attachment 1: Amended Agreement with Dudek.
Related Items “On File” with the Clerk of the Board:
None