Oregon's DEQ 1200-C Construction Stormwater Permit Explained

The Permit That Catches Owners Off Guard

A lot of property owners discover the DEQ 1200-C permit the hard way — partway into a project, when a regulator asks where their stormwater plan is. It's not an obscure rule. It's Oregon's main construction stormwater permit, and it applies to a wide range of projects that disturb a meaningful amount of ground. Knowing whether you need it before you break ground saves stop-work orders, fines, and scramble.

This guide explains what the 1200-C permit is, when it kicks in, and what it requires. It's general guidance — your specific project should be confirmed with DEQ or your jurisdiction. For broader context, see our Oregon drainage guide and drainage permit requirements guide.

What the 1200-C Permit Is

The 1200-C is Oregon's National Pollutant Discharge Elimination System (NPDES) general permit for construction stormwater, administered by the Oregon Department of Environmental Quality (DEQ) and, in some areas, by agents like local agencies. Its purpose is to keep sediment and pollutants out of state waters during construction by requiring sites to plan for, install, and maintain erosion and sediment controls.

Construction disturbs soil, and disturbed soil washes into streams during Oregon's rains. The 1200-C is the mechanism that holds construction sites accountable for managing that runoff.

The One-Acre Threshold

The headline trigger is disturbing one acre or more of land. That includes clearing, grading, excavating, and stockpiling. The acre threshold also applies to smaller sites that are part of a larger common plan of development — so a 0.3-acre lot within a multi-acre subdivision can fall under the permit even though the individual lot is under an acre.

Below an acre and not part of a larger development, the 1200-C generally doesn't apply — but local erosion control rules often do, sometimes at much smaller thresholds. So "under an acre" doesn't mean "no rules"; it means check locally. Our drainage permit requirements guide covers the local-permit side.

The ESCP: Heart of the Permit

The core deliverable is an Erosion and Sediment Control Plan (ESCP). This is a site-specific plan showing how the project will prevent erosion and keep sediment on site. It identifies:

• The disturbed areas and drainage patterns
• Which BMPs go where — silt fence, wattles, inlet protection, sediment basins, stabilized entrances
• Erosion controls like cover, seeding, and blankets
• How and when controls are installed, maintained, and removed
• The discharge points and how runoff is managed

The ESCP isn't a one-time form; it's the operating manual for keeping the site compliant. Our sediment control BMPs and erosion control excavation guides cover the practices it specifies.

Inspections and Recordkeeping

Holding the permit comes with ongoing obligations:

• Regular inspections of the BMPs — typically on a set schedule and after significant storm events — to confirm controls are working and catch failures early.
• Maintenance of the controls based on what inspections find: cleaning out silt fence and inlets, repairing damage, replacing buried wattles.
• Records documenting the inspections, rainfall, and corrective actions, kept on site and available to regulators.

This is where many sites stumble. Installing BMPs is straightforward; keeping them maintained and documented through a wet Oregon winter takes discipline. A site with great controls but no inspection records can still be out of compliance.

Who Needs It and Who's Responsible

The permit registrant is typically the project owner or developer, often working with the contractor who installs and maintains the controls. Responsibility for compliance generally rests with the permittee, so it's worth being clear up front about who handles the ESCP, the inspections, and the records. On many projects the excavation contractor implements and maintains the BMPs on the ground while the owner holds the permit — but the arrangement should be spelled out, not assumed.

Plan for It Before You Dig

The expensive way to learn about the 1200-C is mid-project. The smart move is to evaluate the permit need during planning: estimate the disturbed area, check whether the site is part of a larger development, confirm with DEQ or the local agent, and build the ESCP and BMP costs into the project from the start. A site that's set up for compliance from day one avoids stop-work orders and runs smoother through the rainy season.