FSP
Future Storm Protection
Proposed control level
- Uses forward-looking climate assumptions.
- Would remove CSO discharges in the projected 2050 Typical Year.
- Already represents a major climate-forward infrastructure obligation.
CSO Resources
Cleaner Rivers. Clearer Choices. Responsible Decisions.
The Draft Updated CSO Long-Term Control Plan will shape obligations for decades. The Advisory Board supports continued CSO progress and cleaner rivers. We also believe the next decision must be made with full visibility into the value delivered, the burden imposed, and the impact on communities ultimately responsible for paying.
Public comments due October 30, 2026
Start with the Dashboard, understand the choice before the region, then use the questions below to decide what you want to say during public review.
Page Sections
Public Review Period
Now is the time to bring community impacts into view.
The Draft Updated CSO Long-Term Control Plan is in public review, with comments due September 30, 2026. Communities, officials, staff, and stakeholders should understand what each alternative delivers, what it costs, and how those obligations would fall across communities.
The Decision
What decision is actually being made?
The choice is not whether cleaner rivers matter. They do. The choice is how far the region should go, what additional value that delivers, and who carries the obligation.
Remaining CSOs
What remaining discharges are being addressed?
Control Alternatives
Which planning options drive the central cost comparison?
Community Obligation
Who pays, when, and for how long?
Core Comparison
FSP and ESP frame the cost question.
The broader planning process evaluated multiple control levels. The Dashboard focuses on FSP and ESP because they show the difference between the proposed control level and the higher-control alternative.
ESP
Extreme Storm Protection
Higher-control alternative
- Goes beyond the typical-year control standard.
- Creates a materially larger extreme-storm obligation.
- Raises the question of added public value versus added community burden.
Core Advisory Board Question
Added benefit
Additional water-quality improvementWhat does the higher-control alternative deliver beyond the proposed control level?
Additional water-quality improvementWhat does the higher-control alternative deliver beyond the proposed control level?
Added obligation
Cost, construction, debt service, and durationWhat would communities and ratepayers carry, and for how long?
Cost, construction, debt service, and durationWhat would communities and ratepayers carry, and for how long?
Does the added benefit justify the added community obligation?
This decision is about
Remaining CSO controls
How far the region should go in controlling remaining combined sewer overflows.
The alternative selected
Whether the plan should proceed with Future Storm Protection or go further toward Extreme Storm Protection.
Community responsibility
How costs, debt service, construction impacts, and long-term obligations fall on communities and ratepayers.
This decision is not about
Whether sewage in waterways is acceptable
It is not.
Whether stormwater or urban flooding matter
They do, but they are not solved by a CSO-only mandate.
Whether higher control is automatically better policy
The question is whether the added public benefit justifies the added obligation.
Next: download the Dashboard to see how the alternatives translate locally.
Excel-Based Decision Tool
CSO Long-Term Cost Dashboard
Downloadable Excel file
Downloadable Excel Dashboard
Start with the Community Cost Dashboard.
The Advisory Board’s downloadable Excel Dashboard translates regional CSO alternatives into community-level cost estimates. It helps users see how costs are distributed, when they are paid, and how long communities would carry the obligation.
Use the Dashboard to see:
- how costs compare across alternatives;
- when costs and debt service occur; and
- how long communities would carry the obligation.
Next: compare the alternatives directly.
Alternative Comparison
Future Storm Protection vs. Extreme Storm Protection
The Dashboard focuses on these two alternatives because they define the central community-cost comparison. Both are forward-looking. The question is how far beyond the Future Storm Protection standard the region should go.
What rainfall standard is being used?
FSP
Projected 2050 Typical YearUses forward-looking rainfall assumptions, not simply historical rainfall.
Projected 2050 Typical YearUses forward-looking rainfall assumptions, not simply historical rainfall.
ESP
Higher extreme-storm levelGoes beyond the typical-year control standard toward a larger storm-protection obligation.
Higher extreme-storm levelGoes beyond the typical-year control standard toward a larger storm-protection obligation.
What CSO outcome is targeted?
FSP
Zero CSO discharges in the projected 2050 Typical YearRemoves CSO discharges under the projected typical-year condition.
Zero CSO discharges in the projected 2050 Typical YearRemoves CSO discharges under the projected typical-year condition.
ESP
Additional control beyond that levelTargets more CSO control during larger storm conditions.
Additional control beyond that levelTargets more CSO control during larger storm conditions.
What changes for communities?
FSP
Major climate-forward investmentAlready represents a substantial forward-looking infrastructure obligation.
Major climate-forward investmentAlready represents a substantial forward-looking infrastructure obligation.
ESP
Materially larger obligationAdds cost, debt service, construction impact, and long-term community responsibility.
Materially larger obligationAdds cost, debt service, construction impact, and long-term community responsibility.
The core issue is not whether cleaner rivers matter. It is whether the additional control delivers enough additional real-world benefit to justify the additional obligation.
Next: new to CSOs? Start with the basics. Otherwise, continue to the water-quality outcome question.
New to CSOs?
Start with the basics.
New to CSOs? Start here. These basics give enough background to follow the plan, the Dashboard, and the public-comment process.
What is a combined sewer overflow?
A CSO happens when an older combined sewer system carrying both sewage and stormwater reaches capacity during wet weather and releases overflow to a nearby waterway.
Why were CSOs built?
CSO outfalls were designed as relief points. During heavy rain, they reduce the risk of sewage backing up into basements, streets, and buildings.
Why are CSOs a problem?
CSOs can discharge sewage and stormwater into waterways. Reducing them remains an important public-health and environmental goal.
Why does the design standard matter?
The selected design standard determines the level of infrastructure required, the cost, the construction burden, and what kinds of storms the system is expected to control.
New visual explainer: CSOs and Stormwater Runoff: Two Different Sources of River PollutionThe Advisory Board is beginning an anticipated series of visual CSO explainers with a first installment on stormwater: how it differs from a CSO, why it still affects river conditions, and why CSO control is necessary but not sufficient by itself.
Real-World Outcome
CSO control is necessary. It is not sufficient by itself.
☔Stormwater
Stormwater and runoff remain major contributors to water-quality conditions.
⌁CSOs
CSO pollution is real, and reducing discharges remains important.
▣Other sources
Dry-weather sources, upstream conditions, and other pollution pathways also affect river outcomes.
Outcome, Not Just Control
More CSO control is not automatically the same as better river conditions.
A higher-control CSO requirement may sound like the finish line. But if stormwater and other pollution sources continue to shape water quality, the region could spend substantially more without proportionate improvement in the river conditions people expect.
The question is not whether cleaner rivers matter. They do. The question is whether each additional level of CSO control delivers enough documented benefit to justify the full cost and community burden.
For a visual explanation of why stormwater can still affect river conditions even when no CSO occurs, view the new CSO and Stormwater Runoff Explainer. Additional explainers are expected in the future as this resource hub continues to grow.
Next: look at what “burden” really means.
Full Community Obligation
The impacts are more than capital cost.
The community is where the bill becomes real. Any higher-control requirement should be evaluated across the full set of obligations it creates, not just the headline construction cost.
Capital costLook forTotal project cost and who pays.
Why it mattersSystemwide scale can hide community-level obligation.
Debt serviceLook forHow long costs remain in assessments.
Why it mattersRepayment can extend decades beyond construction.
Construction impactsLook forDisruption, staging, access, and neighborhood impacts.
Why it mattersEnvironmental infrastructure still has local consequences.
Land and open spaceLook forPotential use of parks, fields, or constrained urban sites.
Why it mattersSome impacts are not captured by dollars alone.
Opportunity costLook forWhat else communities and ratepayers need to fund.
Why it mattersCSOs are part of a broader long-term capital-pressure picture.
Next: use these questions in meetings, comments, and local conversations.
Practical Toolkit
Questions to ask before comments are due.
Use these as a staff briefing tool, comment-letter checklist, meeting prep guide, or local conversation starter.
What added water-quality value does ESP deliver beyond FSP?
The decision should be grounded in documented incremental benefit, not only the idea that a higher-control standard sounds stronger.
Does the alternative solve the outcome people expect?
If stormwater and other pollution sources remain, a CSO-only mandate may not produce the river conditions the public assumes it will.
What does this mean for my community’s assessments?
The Dashboard is intended to help translate regional alternatives into community-level financial exposure.
How long would communities carry the obligation?
Debt service, repayment timing, and the long tail of assessments should be part of the decision.
What local impacts come with the added infrastructure?
Construction disruption, staging, access, land needs, and neighborhood impacts should be visible alongside project costs.
What tradeoffs does this create for other local and regional needs?
CSOs are part of a broader long-term capital-pressure picture that also includes water, wastewater, stormwater, climate, housing, transportation, schools, and other priorities.
Take Action
Participate before comments are due.
Public comments on the Draft Updated CSO Long-Term Control Plan are due September 30, 2026. Use the Dashboard, the questions above, and your local knowledge to help bring community impacts into the public-review record.
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Use the Dashboard
Download the Advisory Board’s Excel-based Dashboard to see how regional alternatives translate into community-level costs, timing, and long-term obligations.
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Brief your community
Use this page, the Dashboard, the walkthrough video, and the new CSO and Stormwater Runoff Explainer to brief local officials, staff, boards, councils, or community stakeholders.
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Ask targeted questions
You do not need a full technical filing to participate. Useful comments can ask clear questions about added benefit, local impacts, cost timing, and tradeoffs.
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Submit comments
Comments can be submitted online, by email, by mail, or verbally at a virtual public hearing. The Partners’ project page includes the current submission instructions and hearing registration links.