Winery Wastewater Rules: The Statewide Winery Order and County Permits
The main California rule for wineries that send process water to land, through ponds, irrigation or a subsurface disposal system, is the State Water Board’s statewide Winery Order, Order WQ 2021-0002-DWQ, adopted January 20, 2021. It covers facilities generating 10,000 to 15,000,000 gallons of process water a year and sorts them into four tiers by design flow. In Napa County, wineries in the county’s long-running program have until January 20, 2027 to move to the statewide order.
Process water is the water used to clean tanks, barrels, presses, floors and bottling lines. It carries sugars, solids and salts, so it is treated and disposed of separately from a household septic system, even when the two share a site. For a buyer, the wastewater system is often the hard limit on how much wine a property can make and how many visitors it can serve. This guide explains the rules and the records to request, and it supports our winery due diligence checklist.
The statewide Winery Order in brief
The State Water Resources Control Board adopted the General Waste Discharge Requirements for Winery Process Water, with Resolution No. 2021-0001, on January 20, 2021. Its fee schedule followed on July 6, 2021, in Title 23 of the California Code of Regulations, sections 2200 to 2200.9. The State Board’s fact sheet, updated January 3, 2024, estimates that about 30% of roughly 6,200 bonded California wineries are eligible.
The order applies to discharges to land. According to the San Francisco Bay Regional Water Board, that includes process water ponds, irrigation land application and septic-subsurface disposal systems. A winery that sends all its process water to a public sewer under a sanitation district’s pretreatment rules is handled differently; the Napa County program, for example, lists sewer discharge as its own category.
| Tier | Annual permitted process water design flow | Notes from the order |
|---|---|---|
| Exempt | Less than 10,000 gallons | No enrollment, but no discharge to surface waters, no hazardous or untreated waste, and management practices still apply; the board can direct a winery to apply as Tier 1 |
| Tier 1 | 10,000 to 30,000 gallons | Flow may be measured by an accurate alternative to a flowmeter |
| Tier 2 | 30,001 to 300,000 gallons | Salt and nitrogen thresholds can trigger control plans |
| Tier 3 | 300,001 to 1,000,000 gallons | Same salt and nitrogen framework, with more monitoring |
| Tier 4 | 1,000,001 to 15,000,000 gallons | Groundwater monitoring at ponds, land application areas and subsurface systems, unless the regional board grants an exemption |
The tier also sets the annual fee. Because tiers follow design flow, not last year’s actual production, an owner planning to grow should check whether the plan crosses a tier line.
What the order requires
The order’s findings describe the main technical limits. They are summarized here so a buyer knows what to ask about; the order itself and the facility’s notice of applicability control.
- Land application. Nitrogen applied at no more than the crop’s agronomic rate, with an annual nitrogen balance, and a cycle-average BOD loading limit of 100 pounds per acre per day.
- Subsurface disposal. Effluent limits before disposal of 10 mg/L total nitrogen, 300 mg/L BOD and 330 mg/L total suspended solids, and a hydraulic loading limit of one gallon per square foot of trench per day.
- Salt. For Tiers 2 to 4, effluent fixed dissolved solids are compared with a threshold equal to the source water concentration plus 320 mg/L. An exceedance can require a salt control plan, though it isn’t itself a violation.
- Ponds. New ponds are generally sized to contain a 100-year, 24-hour storm, with exceptions requiring regional board approval. Existing Tier 1 and Tier 2 ponds may keep their current lined or unlined status.
The fact sheet notes that wineries can use salt and nutrient management plans to help comply, and that some may request groundwater monitoring in place of subsurface effluent limits with regional board approval.
Deadlines for existing, new and expanding wineries
- Existing wineries (operating on or before January 20, 2021) without other coverage had to submit a notice of intent, fee and technical report within three years of adoption, which the San Francisco Bay board gives as January 20, 2024. The order allows a compliance schedule of up to five years from the notice of intent.
- New wineries must submit the notice of intent and technical report at least 180 days before operations begin. The San Francisco Bay board applies the same 180-day lead time to expanding wineries.
- Tier changes need a new notice of intent and technical report at least 120 days before the anticipated change.
- Closing down a discharge requires a notice of termination at least 120 days before all discharge activities stop.
Enrollment runs through an electronic notice of intent in the state’s CIWQS system, followed by the application fee and a signed copy sent to the regional board. A facility moving over from existing permit coverage doesn’t pay a separate application fee, according to the State Board.
Napa County: the county program and the 2027 transition
Napa County has regulated winery wastewater since 1979, according to a county presentation hosted by the State Water Board. The San Francisco Bay Regional Water Board says wineries in Napa’s Winery Waste Discharge Program that were approved for extended coverage must complete the transition by January 20, 2027; the deadline to apply for that extension has passed.
Until Napa County is authorized to implement the Winery Order, an updated memorandum of understanding lets the county’s Planning, Building and Environmental Services department issue operating permits and oversee existing permitted wineries that discharge to land. The county presentation groups wineries by system type:
- Wineries already under the statewide order or an individual Regional Board permit.
- County-regulated systems, including hold-and-haul, engineered systems, ponds, and conventional systems above 1,500 gallons per day.
- Sanitation district pretreatment with discharge to sewer.
- Conventional systems producing less than 10,000 gallons of process wastewater a year, which need no permit.
The presentation tells permitted wineries to stay in compliance and check with the county before changes such as more process wastewater, more domestic wastewater mixed with process water, new treatment or a new disposal method. For new or expanding wineries that need a use permit, the state’s notice of applicability must be issued before the county issues its permit. The county’s Well and Onsite Wastewater Treatment section permits and inspects alternative sewage systems, winery wastewater ponds and holding tanks. Our Napa winery use permit guide covers the land-use side.
Sonoma County and the North Coast Regional Water Board
Sonoma County wineries can fall under either the North Coast Regional Water Board (Region 1) or the San Francisco Bay board (Region 2), depending on the watershed, so start with the Water Boards’ regional map for the parcel.
As of its page updated April 15, 2026, the North Coast board runs a Wine, Beverage and Food Processor program alongside the statewide order:
- Regional general permit. General WDRs, Order No. R1-2016-0002, adopted January 28, 2016, which replaced the board’s 2002 general winery permit and extended coverage to other beverage and food processors.
- Conditional waiver. Small-volume processors, typically under 1,500 gallons per day and sometimes under 3,000 for some wineries, may apply for coverage under a waiver. The page labels Order No. R1-2026-0001 an adopted waiver, dated February 18, 2026, replacing Order No. R1-2021-0001. Its linked order file is still marked draft, so confirm the final terms with board staff.
- Transition plan. The board’s first priority is enrolling wineries with no coverage into the statewide order; the second is moving wineries already under a regional permit or waiver. The page says implementation has been delayed and will proceed as resources allow.
So a North Coast winery may hold regional coverage, waiver coverage, statewide coverage or none. Ask the seller which applies, then confirm with board staff. Sanitary sewage from tasting rooms and staff is a separate county permitting question; our guide to wells, septic and rural utilities in Sonoma County covers the county side, and our Sonoma County winery use permit guide covers production and visitation limits.
What buyers should review
A winery’s wastewater file tells you whether the system can support the production, events and visitors you are paying for. Ask for these documents early, because regional board and county records can take weeks to obtain.
| Document | What to check |
|---|---|
| Notice of applicability, regional permit, waiver or county operating permit | Which order covers the site, the tier or permitted flow, and the effective date |
| Technical report and system design | Design flow for process and sanitary water, and whether it matches current and planned production |
| Monitoring and annual reports | Flow records, nitrogen and salt results, and any exceedances or control plans |
| Notices of violation and correspondence | Open enforcement, compliance schedules and promised upgrades |
| Use permit conditions | Wastewater conditions tied to production gallons, visitors and events |
| Pond, tank and leachfield inspections | Liner condition, storm capacity, pump and alarm function |
| Hauling records | For hold-and-haul systems, the volumes and the licensed hauler’s receipts |
If other brands make wine on site, their process water runs through the same system and counts toward its design flow; our guide to custom crush and alternating proprietorships explains those arrangements. Water supply is a separate review; for Napa parcels, see our Napa groundwater rules.
Then ask three practical questions. Does the planned production or event program push the design flow into a higher tier? Is a Napa winery in the county program ready to move to the statewide order by January 20, 2027, and at what cost? How will coverage pass to a new owner?
The order’s standard provisions and the regional board set the transfer steps, so confirm them with board staff before closing.
A civil engineer who designs winery wastewater systems is the right reviewer for the technical file. Diamond may refer you to partners we work with; you’re free to choose any provider. Our vineyard due diligence guide covers the farming side of the same purchase, and our pages on winery production facilities and winery valuation explain how a constrained system affects price.
This is general information, not legal or engineering advice; have a wastewater engineer review the system and a California environmental or land-use attorney review the permits before you buy or expand a winery.
Questions people ask
What is the Winery Order WQ 2021-0002-DWQ?
The State Water Board’s general waste discharge requirements for winery process water, adopted January 20, 2021. It covers wineries generating 10,000 to 15,000,000 gallons of process water a year that discharge to land, in four tiers by design flow.
Does a small winery need a wastewater permit?
A winery producing less than 10,000 gallons of process water a year is exempt from enrolling, but it still may not discharge to surface waters and must follow management practices. The regional board can still direct it to apply as Tier 1.
Can winery process water go into a septic system?
It can go to a subsurface disposal system designed and permitted for it. The statewide order sets effluent and loading limits for those systems, and counties regulate the onsite systems themselves.
When must Napa wineries move to the statewide Winery Order?
Wineries in Napa County’s program that received extended coverage must transition by January 20, 2027. The deadline to apply for that extension has passed.
What happens if a winery expands production?
If the expansion changes the tier, a new notice of intent and technical report are due at least 120 days before the change. The San Francisco Bay board says expanding wineries apply at least 180 days before the expanded operation starts.
Which regional water board covers a Sonoma County winery?
Either the North Coast board or the San Francisco Bay board, depending on the watershed. Check the Water Boards’ regional map for the parcel and confirm coverage with that board’s staff.
Does winery wastewater coverage transfer to a buyer?
Coverage is issued to the enrolled discharger, so a sale needs whatever transfer steps the order and the regional board require. Confirm them with board staff and build the timing into escrow.
If you’re buying, selling or expanding a winery in Napa or Sonoma, we can help assemble the wastewater file early and coordinate it with your engineer’s review. Talk to Diamond’s vineyard and winery team.
Sources & notes
- State Water Resources Control Board: General Order for Winery Process Water (page updated July 13, 2026)
- State Water Resources Control Board: Order WQ 2021-0002-DWQ
- State Water Resources Control Board: Winery Order fact sheet (updated January 3, 2024)
- San Francisco Bay Regional Water Board: Winery Program (updated August 19, 2026)
- North Coast Regional Water Board: Wine, Beverage and Food Processor Wastewater Program (updated April 15, 2026)
- Napa County PBES: Winery wastewater program presentation (2024 webinar, hosted by the State Water Board)
- Napa County: Well and Onsite Wastewater Treatment
Technical limits are summarized from the order’s findings; the order’s provisions and each facility’s notice of applicability control.
Last reviewed October 2026 by Matthew Martinez.
