Wisconsin's low-impact discharge permit for power washers
Does Wisconsin's low-impact discharge permit apply to a mobile pressure washing business?
The permit that names mobile commercial power washing
Wisconsin's low-impact discharge general permit lists mobile commercial power washing and contract washers among the outside washing activities it can cover.
That is the sentence most crews miss. The permit is not written only for car washes and truck yards. A business that shows up at many sites with a tank and a hose is named in the applicability section.
Naming an activity does not make coverage mandatory for every job. Coverage matters when wash water reaches a water of the state. Where wash water can go sorts the routes by that test.
The permit may cover outside washing activities including mobile commercial power washing or contract washers. — Wisconsin DNR, Low-Impact Discharge general permit WI-0066575-01-0, retrieved 2026-09-29
Four conditions all have to be true
Coverage needs four things together. The DNR must find the discharge free of pollutants that threaten water quality standards, and you must send a complete notice of intent and receive a coverage letter.
You must also submit discharge screening results with the notice, and the department must find that the discharge passes. Last, you must file a complete best management practice plan with the notice for approval.
Miss any one and the permit does not apply. The plan is the heavy piece, so the application guide walks through it in order.
Coverage requires a DNR finding, a complete notice of intent and coverage letter, passing screening results, and a DNR-approved BMP plan. — Wisconsin DNR, Low-Impact Discharge general permit WI-0066575-01-0, retrieved 2026-09-29
One statewide coverage instead of one per site
A mobile crew does not apply for each address. The permit allows statewide coverage for facilities that perform operations with temporary discharges at multiple locations.
Permittees with statewide coverage do not reapply each time a discharge to a water of the state occurs within the coverage area. One approved plan can cover every job, if it addresses each discharge type you meet.
That suits the trade. A crew that works a lake town on Monday and a city lot on Thursday holds one permit and one plan.
Statewide coverage applies to facilities with temporary discharges at multiple locations, with no reapplication for each discharge. — Wisconsin DNR, Low-Impact Discharge general permit WI-0066575-01-0, retrieved 2026-09-29
No DNR application fee for most general permits
The DNR does not charge permit application fees or annual fees for most wastewater general permits. The one exception on its list is the ballast water permit.
The cost of coverage is therefore time and paperwork, not a fee. You write the plan, keep records and train crew.
Notices go in electronically. Send the notice at least 30 business days before you expect to start discharging, because you may not discharge to waters of the state until the coverage letter arrives.
The DNR does not charge application or annual fees for most wastewater general permits; the ballast water permit is the exception. — Wisconsin DNR wastewater general permits page, retrieved 2026-09-29
30 business daysThe notice of intent goes in at least 30 business days before the expected start of discharge. — Wisconsin DNR, Low-Impact Discharge general permit WI-0066575-01-0, retrieved 2026-09-29
What the screening asks for washing crews
For outside washing, the permit's screening is narrative only. You certify that the discharge meets plain-language conditions, and you check them by looking at the water.
The conditions cover oil sheen or film, objectionable odor and color, and floating solids, submerged solids, foam, scum and debris. The permit also bars unapproved water treatment additives.
Lab sampling parameters apply to other activities on the list, such as maple syrup wastewater. Washing crews certify by eye and record what they saw, which is why the job-site checklist includes a discharge look.
For washwater from outside washing, screening uses narrative discharge requirements only, with no lab parameters. — Wisconsin DNR, Low-Impact Discharge general permit WI-0066575-01-0, retrieved 2026-09-29
Questions
Does every pressure washer in Wisconsin have to hold this permit?
The permit does not say so. It sets conditions for discharges to waters of the state and names mobile power washing as an activity it can cover. Whether a job needs coverage turns on where the water goes, so confirm with the DNR general permit reviewer for your region.
Who reviews the notice of intent?
The permit tells applicants to submit through the DNR's general permit process, and the DNR lists a general permit reviewer for each region. That reviewer is the person to ask about a particular job.
Does the permit cover a homeowner washing their own deck?
The permit lists noncommercial washing at individual residences as not applicable to it. It is a permit for commercial washing. Your customer's deck is still your commercial job, even though it sits at a house.