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2021 Storm and Surface Water Master Plan Update
Bothell City Council voted unanimously to adopt the 2021 Storm and Surface Water Master Plan Update during its Oct. 20, 2020 regular meeting and Public Hearing. City staff held a virtual open house in September 2020 and would like to thank everyone who shared their questions and concerns with us through our online feedback form.
Prior to this update, the City’s Storm and Surface Water Master Plan was last updated in 2015. This plan sets a course for stormwater programs and capital projects for the coming years and addresses current and anticipated regulatory requirements, emerging stormwater management technologies, existing flooding and water quality problems, and the resources the City needs to fully implement its plan.
Adopted 2021 Storm and Surface Water Master Plan Update
All documents below are in PDF format.
Click each tab below to read a brief summary of each section of the document. To read the complete contents of each section or to open the entire document as a PDF, click the document links just above this section.
- Program Overview and Evaluation
- Project Planning
- Watershed Management
- Financial Management
- Recommended Actions
Section 1 provides an overview and evaluation of the Utility’s functions and recommends program actions where appropriate. Although compliance with federal regulations under the Clean Water Act - National Pollution Discharge Elimination System (NPDES) Permit is a significant driver for the Utility’s program, this Plan Update recognizes that the Utility provides a broader range of services than simply complying with regulations.
Focus areas for the program evaluation and summary overview include:
Systems Operations and Management
- Inspecting, cleaning, and maintaining the City storm system
- Identifying and correcting deficiencies in the City-maintained system
- Requiring private system operators to maintain their systems
- Identifying and completing Natural Environment Projects
Regulatory Compliance
- Tracking and responding to NPDES and other state and federal requirements
Stormwater Pollution Control
- Spill response
- Illicit connection and discharge elimination
- Stream and system monitoring, evaluation, and testing
- Education and outreach targeting behavior change
- Technical assistance for business owners to repair and maintain their systems
System Expansion (through Land Use and City Projects)
- Review and inspection of stormwater reports and designs
- Creation and updating of stormwater design standards
- Tracking and integrating new construction into inspections and asset management
Financial Planning and Management
- Rate setting and billing
- Financial tracking
- Asset management funding
Reporting and Record Keeping
- Internal records management
- Maintenance and Asset Management database
Summary of Evaluation
No major overhaul or expansion of the Utility is planned during 2021-2025. The Utility is expected to raise rates slightly over time to meet its minimum long-term program needs. Significant effort will be necessary in the next two years to address the following items associated with the City’s NPDES permit:
| Task / Item | Due Date |
|---|---|
| Implement a community-based social marketing strategy | Due Mar. 31, 2021 |
| Watershed delineation and prioritization | Due Dec. 31, 2021 |
| Long-range comprehensive planning | Due Mar. 31, 2022 |
| Implement source control program for existing development | Due Dec. 31, 2022 |
| Development of a stormwater management action plan | Due Dec. 31, 2022 |
| Low impact development code review | Due Dec. 31, 2023 |
| Evaluate and report on behavior change for marketing strategy | Due Mar. 31, 2024 |
Staffing and Equipment Needs
Based on an assessment of its current program, the Utility-funded staffing and equipment levels are adequate to handle existing needs. However, some significant additions to the Utility are being considered through land use changes in the Canyon Park Business Park and future improvements by the City and private development. These additions will be assessed prior to completion of these planning efforts and additional staff and equipment may be included in subsequent rate studies.
Open a PDF of the entire Program Overview and Evaluation section (Section 1) of the Adopted 2021 Storm and Surface Water Master Plan Update.
Project Planning
Section 2 identifies major drainage and natural environment, retrofit, replacement, and other projects that are appropriate and fundable within the 2021-2025 planning period.
Major Drainage and Natural Environment Projects
The 2021-2025 planning period begins with significant spending associated with other utility and transportation projects. A large portion of the funding for the projects is expected to come from City utility funds which will be offset by grants when available.
The full rate study scheduled in 2021 will provide a better financial understanding of what is needed to manage operating and capital expenditures in the long term. Assuming rates and expenses follow current expectations, the Utility is forecasting to invest a total of over $14.9 million from 2021-2025 to address problems.
Facility Retrofit Projects
As of 2020, the Utility directly manages over 396 stormwater flow control and treatment facilities (mostly ponds and vaults). Many of these facilities were built to older design standards and do not provide the same performance as what is currently required.
These Utility-managed facilities represent a potential opportunity to improve surface water conditions because the facilities could be retrofitted with new designs that provide improved function. Although no detailed analysis of the costs to retrofit facilities has been performed, this Plan Update includes $500,000 during 2021-2025 to fund facility retrofits. Facilities will be prioritized based on watershed management area needs, opportunities, and action planning.
System Replacement Projects
In addition to fixing problems and restoring natural surface water areas, the Utility accounts for replacement of aged infrastructure like pipes, catch basins, and stormwater vaults. The Utility annually expenses over $400,000 for the depreciation of its infrastructure. From 2021-2025, this amounts to a total of over $2 million that is to be depreciated for system replacement. A portion of the capital projects in this Plan Update includes system replacement.
Open a PDF of the entire Project Planning section (Section 2) of the Adopted 2021 Storm and Surface Water Master Plan Update.
Watershed Management
Section 3 of this Plan Update provides an overview of the Utility’s watershed management efforts. This section identifies an additional approach to help focus these efforts.
The approach divides the Utility’s service area into eleven sub-areas, termed surface water management areas (SWMAs). Bothell’s SWMAs were altered from the previous Plan to meet Washington State Department of Ecology requirements under S5.C.1.d.i of the Western Washington Phase II Municipal Stormwater (MS4) Permit. SWMA sizes were defined to meet Ecology expectations, data gathering and reporting needs, and allow the City to reasonably measure or detect improvements in water quality from implemented projects and programs. When basin delineations are too small, the amount of data required throughout the city to prioritize between them is too great. When basins are too large, areas get unfairly biased from size requirements. Due to this, Bothell’s SWMA basins focus on tributary drainage to reduce bias, meet size requirements, and focus on areas where the City can implement improvements with the potential to detect change through future monitoring.
Following this approach, Bothell’s delineated SWMAs range from 0.7 to 6.7 square miles. Only one basin, Little Bear Creek, fell below the minimum size requirement of 1 square mile when measuring its tributary drainage, but including the entire basin (~15 square miles) would have caused it to exceed the maximum size requirement of 10 square miles. All other SWMAs fell between the required thresholds, with at least 10 percent of the total basin size within Bothell city limits for each basin. The SWMAs were created by combining smaller sub-basins in close proximity to achieve similarly sized basins while still adhering to water drainage patterns. Larger tributaries, such as Horse Creek and Perry Creek, were used to decide where to split larger basins (North Creek and the Sammamish River) due to their potential effect on receiving waterbodies. In order for a tributary’s drainage area to be included in the total area calculation of its SWMA, some portion of the tributary’s drainage basin had to intersect Bothell city limits. Each surface water management area was then given an initial management strategy and a preliminary set of actions.
Surface Water Management Areas
The delineated surface water management areas are:
- Horse Creek
- Juanita Creek
- Little Bear Creek
- Little Swamp Creek
- Lower North Creek
- Lower Sammamish River
- Parr Creek
- Perry Creek
- Swamp Creek
- Upper North Creek
- Upper Sammamish River
An action item of this Plan Update is to further develop the strategies and develop action plans for each of the surface water management areas. A complete discussion of these surface water management areas is found in Section 3.
Open a PDF of the entire Watershed Management section (Section 3) of the Adopted 2021 Storm and Surface Water Master Plan Update.
Financial Management
Section 4 includes a financial review of the Utility for 2021-2026 focusing on the following:
Financial performance and projected fund health
It is projected a gradual rate increase will be required over the next six years for the stormwater Utility fund’s health. For 2020-2023, the Utility’s cash flow is projected to be adequate to meet operations requirements and fund several projects; however, increased project costs due to fish passable requirements will require additional resources.
The current NPDES permit term ends in 2024. Additional resources to implement new requirements in the next permit cycle may be needed, but staff cannot predict at this time what those measures could be. For example, implementation of priority projects identified in the Stormwater Management Action Plan (SMAP) are likely, and new structural stormwater control (SSC) requirements are anticipated for NPDES Phase 2 communities based on past Ecology actions.
Current billing structure
The Utility currently bills stormwater fees based upon a tiered rate structure that groups properties into categories based on ranges of impervious surface area. A full review of the billing structure is planned to be completed in 2021 with the projected rate study to ensure fair and equitable collection practices.
Bill collection alternatives
Stormwater billing is currently administered through Snohomish and King County property tax billing services. This approach was evaluated in 2016 and determined to be the best alternative over direct Utility billing and third-party billing.
Asset replacement
The Utility’s expenses include over $400,000 per year to depreciation of the stormwater system. This expense is intended to assure that the Utility has adequate resources to replace aged infrastructure. The Plan Update identifies that over $2 million dollars will be expensed between 2021 and 2025 toward depreciation.
Open a PDF of the entire Financial Management section (Section 4) of the Adopted 2021 Storm and Surface Water Master Plan Update.
Recommended Actions
Section 5 of the Plan Update compiles actions identified in prior sections. It includes a discussion of potential costs, funding sources, and timelines for actions. Key priorities for the Utility include:
Critical Actions
- C1: Long-range comprehensive planning
- C2: Low impact development (LID) code review
- C3: Watershed delineation and prioritization
- C4: Implement source control program for existing development
- C5: Implement and evaluate a community-based social marketing strategy
- C6: Complete planned drainage and environmental projects
- C7: Review and update Utility rates to keep them current
High Actions
- H1: Evaluate implementation of private inspection program
- H2: Review and update maintenance standards for new facilities
- H3: Continue to map size and material for all known outfalls
- H4: Implement a progressive enforcement strategy for source control
- H5: Train all municipal staff to correctly identify and report spills
- H6: Evaluate construction site runoff ordinances and pre-con site inspections
- H7: Develop a Utility-operated facility retrofit plan
- H8: Clarify Utility’s role in City critical areas management
- H9: Review Utility’s Emergency Preparation planning
- H10: Develop Surface Water Management Area (SWMA)-based strategies and actions
Medium Actions
- M1: Continue to coordinate with surrounding permittees with interconnected MS4
- M2: Continue oversight of North Creek Levee System maintenance
- M3: Evaluate project and program impacts from climate change
- M4: Evaluate project and programs for environmental justice
- M5: Prepare for 2024 NPDES Permit issuance
- M6: Prepare next Master Plan Update
More detailed descriptions of the priority actions are included in Section 5.
Open a PDF of the entire Recommended Actions section (Section 5) of the Adopted 2021 Storm and Surface Water Master Plan Update.