We've reviewed a lot of Stormwater Control Plans. Some of them sail through the city in one pass. Others come back looking like a law school exam — comment after comment, half of which are asking for information that was already in the document, formatted in a way the reviewer couldn't find.

This post is about writing one that passes. Not because you got lucky with a lenient reviewer, because the document is actually complete, correctly organized, and demonstrates that the engineer understands what the city is looking for.

We'll walk through what an SCP is, every required section, the parts that most commonly fail review, and how to QC your own document before you hit submit.

what's a Stormwater Control Plan?

A Stormwater Control Plan — called an SCP, or sometimes a Stormwater Management Plan depending on the jurisdiction — is the engineering document submitted with your building permit that proves your project meets C.3 requirements under the Municipal Regional Stormwater Permit (MRP).

If your project creates or replaces 5,000 square feet or more of impervious surface in the Bay Area (or 10,000 SF for single-family homes), you need one. No SCP, no grading permit. It's that simple.

Quick clarification people always ask about: An SCP isn't the same as a SWPPP. A Stormwater Pollution Prevention Plan (SWPPP) covers construction-phase erosion and sediment control — the measures you use while you're grading and building. An SCP covers post-construction permanent BMPs — the bioretention cells, permeable pavement, and flow-control features that stay on your site forever. Both are real requirements. Both go to different reviewers. Don't confuse them in your document or in a conversation with the city.

The Required Sections (Don't Skip Any of These)

Bay Area municipalities follow the MRP framework, with local variations layered on top. Whether you're in Contra Costa County (CCCWP), Alameda County (ACCWP), or Santa Clara Valley (SCVURPPP), the core structure of a compliant SCP looks like this:

1. Project Description

This isn't filler. Reviewers use the project description to establish jurisdiction, trigger level, and which provisions apply. Include: project address and APN, project type (new development vs. Redevelopment), total site area, total new and replaced impervious area, applicable C.3 thresholds, and the specific clean water program you're submitting to. Be specific about the breakdown — a lot of SCP review comments come from reviewers who can't figure out which square footage is new vs. Replaced.

2. Existing Conditions

Describe the site as it exists today: current land use, impervious cover, drainage patterns, receiving waters, and any existing stormwater infrastructure. Include a site map. If the site drains to a creek, name the creek. If it drains to a storm drain that outfalls to the Bay, say that. Reviewers need to understand the baseline before they can evaluate your proposed changes.

3. Proposed Conditions

This section describes what you're building. New impervious surfaces, their materials, and how they drain. Where the roof drainage goes. Where the parking lot drainage goes. This sets up the DMA delineation in the next section — everything flows from this description, literally.

4. Impervious Area Calculations

This is where a lot of SCPs fall apart. You need a clear, auditable calculation of all impervious areas: new impervious, replaced impervious, and any credits for areas that qualify as self-treating or self-retaining (more on those in a moment). The total must be traceable from your civil drawings. If the reviewer pulls up Sheet C-2 and your impervious area table doesn't match the SCP, you're getting a comment.

Lay this out in a table. Show your work. Don't make the reviewer back-calculate your numbers.

5. Drainage Management Area (DMA) Delineation

This is the foundation of the entire document, and it's the single most common source of major review comments.

A Drainage Management Area (DMA) is a discrete drainage sub-basin within your site. Every square foot of impervious surface on your project must be assigned to a DMA, and every DMA must be directed to a specific stormwater control measure (or classified as self-treating or self-retaining, with documentation to support that classification).

Draw your DMAs carefully. They need to match your grading plan — the drainage should actually flow the way you've drawn it. If your inlet is in the northeast corner of the parking lot, don't show a DMA boundary that routes the southwest corner to it. Reviewers flag drainage management area delineations that contradict the grading plan constantly.

Self-Treating and Self-Retaining Areas

This is where you can reduce your BMP footprint significantly if your site qualifies.

Self-treating areas are pervious surfaces — landscaping, lawn, uncompacted gravel — that generate little or no runoff. They're treated as if they manage their own stormwater, so they don't need to be routed to a BMP.

Self-retaining areas are areas that receive runoff from impervious surfaces, have enough soil volume and permeability to infiltrate it without overflowing. Think of a large planter that receives roof drainage and doesn't have an overflow — if you can demonstrate it won't overflow during the design storm, it can be classified as self-retaining.

Document both carefully. Reviewers will ask for the calculation showing the self-retaining area's capacity relative to the contributing impervious area. The ratio matters, and it's spelled out in the BASMAA IMP worksheets.

6. BMP Selection and Sizing

For each DMA that requires treatment, you select a Best Management Practice and size it using the BASMAA Integrated Management Practices (IMP) worksheets. These worksheets are the Bay Area standard — they're the calculation engine behind bioretention sizing, flow-through planter sizing, permeable pavement design, and other LID measures.

Common mistakes here:

7. Source Control Measures

Source controls prevent pollutants from reaching stormwater in the first place. This section lists the measures your project will incorporate: covered trash enclosures, roof overhangs at loading docks, spill containment at fueling areas, stenciling of storm drain inlets. These aren't optional — they're required regardless of project size. The list depends on your project type, and most jurisdictions provide a checklist.

For most commercial and multi-family projects, source controls are straightforward. Where we see review comments is on projects that copy-paste a generic list without checking whether every item actually applies to their project type — or where the proposed conditions description doesn't mention features (like a covered trash enclosure) that the source control plan relies on.

8. Operations and Maintenance Plan

This section has to be more than two paragraphs. Reviewers reject vague O&M plans constantly, and they're right to.

A complete O&M plan includes: a description of each stormwater feature installed on the site, the inspection frequency (typically twice per year minimum), specific maintenance tasks for each feature (bioretention: remove trash, check inlet for clogging, replace mulch every two years, inspect for standing water 96 hours after a storm), the responsible party, and how records will be kept.

The O&M plan also needs to reference the O&M Agreement — the recorded legal document that binds the property owner (and all future owners) to maintain the stormwater features in perpetuity. This agreement is recorded against the property with the county before you get your certificate of occupancy. It runs with the land. Future buyers assume the obligation when they take title.

If you're the developer and you're planning to sell the building, disclose the O&M agreement in your sale documents. We've seen due diligence processes get complicated when a buyer's attorney finds a recorded agreement on title they didn't know about.

County-Specific Forms You Can't Skip

On top of the core SCP, each clean water program in the Bay Area has its own required forms:

Submitting the wrong form — or the right form, for the wrong program — will get your application bounced before a technical reviewer even sees it.

How to QC Your Own SCP Before You Submit

Before you hit send, run through this checklist yourself:

  1. Do the impervious area numbers in the SCP match the numbers on the civil drawings? Pull up both documents side by side and reconcile them.
  2. Is every square foot of impervious surface assigned to a DMA? No orphaned areas.
  3. Do the DMA boundaries match the grading plan drainage patterns? Spot-check three spots where they should align.
  4. Is each BMP sized to treat the DMA it serves? Show the link explicitly in the document.
  5. If you're claiming infiltration: do you have geotech data in the appendix? Depth to groundwater and infiltration rate?
  6. Is the O&M plan specific enough that a property manager with no engineering background could follow it?
  7. Are the correct jurisdiction-specific forms attached and completed?
  8. Does the source control list reflect the actual project — not a generic template?

If you're not confident on any of these, a pre-submittal meeting with the city's clean water program is worth the scheduling time. Most Bay Area municipalities offer them. Bring a draft SCP, your site plan, and your impervious area calculations. The reviewer will tell you exactly where the problems are before you're on the clock for a formal review cycle.

We do pre-submittal prep as a standard part of our stormwater engineering work. It's not glamorous, it's the difference between a one-pass approval and a three-cycle slog. Give us a call if you want a second set of eyes on your SCP before it goes in.

And if you're still in the site planning phase — now is the right time to flag the BMP locations. Not after the parking layout is locked.