Find out which stormwater permit governs your site, and what it actually requires

If your project disturbs one or more acres of land you need permit coverage, and a stormwater pollution prevention plan is a condition of that coverage. Below one acre you still need coverage if the project is part of a larger common plan of development or sale that will ultimately disturb an acre or more, which is the trigger people miss most often: a half acre lot inside a 40 acre subdivision is covered. Screen your site above and the tool shows which rule decided it and the permit section it came from.

Under EPA's 2022 Construction General Permit you choose either once every seven calendar days, or once every 14 calendar days plus within 24 hours of a storm producing 0.25 inches or more of rain. If the site discharges to a sediment or nutrient impaired water, or to a Tier 2, 2.5 or 3 water, the increased frequency applies instead: every seven days AND within 24 hours of a qualifying storm. Arid, semi arid and drought stricken sites may qualify for a reduced frequency during the seasonally dry period. A delegated state permit can set different frequencies, and where we have not read that state's permit we say so rather than substituting the federal answer.

A bigger site gets the shorter deadline, which is the opposite of what most people assume. Stabilisation must be initiated immediately, meaning no later than the end of the next business day after earth disturbing activities cease. Completion is within 14 calendar days where five acres or less are disturbed at one time, and within seven calendar days above five acres. Discharging to a sediment or nutrient impaired water or a Tier 2, 2.5 or 3 water forces seven days regardless of acreage, and that override beats the acreage table.

It depends on the state, and the answer is genuinely three sided rather than yes or no. Some states require a credentialed preparer outright: California requires a Qualified SWPPP Developer. Some gate it conditionally, on acreage or on what the plan contains: New York gates only where the plan carries the stormwater management practice component, so an erosion and sediment control only plan has no preparer credential at all. Many states have no preparer credential. Where we have not verified a state we say so and link the agency instead of assuming the permissive answer.

Yes, and it is an absence of code rather than a policy. The screening imports the same engine the paid product and the API run, and it runs it in your browser tab. There is no fetch in that component and no endpoint behind it, so your location, acreage and dates have nowhere to be transmitted and nothing to be stored.

Screening a site is free, with no account and no card: the coverage verdict, the governing permit, the eligibility screens, the inspection frequency, the stabilisation deadlines and every citation. What free does not do is the recurring job, and the recurring job is not a preference here, it is what the permit demands. A covered operator must hold a written site specific plan and must retain an inspection and corrective action record for years. Pro at $49 a month generates that plan document and keeps that record.

No, and it never will. The permit requires a qualified person to physically walk the site on a schedule. We generate the plan and keep the record; the inspection itself is yours. Any product that implies otherwise is selling you a compliance gap.

Basinwise reports publicly published permit requirements and cites the permit section behind each one. It is not legal or engineering advice and it is not a permit. We do not perform the physical site inspections the permit requires; we generate the plan and keep the record. Where a jurisdiction requires a credentialed preparer, the document we generate is a draft for that person to review and sign. Always confirm against your permitting authority's current permit before you break ground.