Environmental Rules in Walla Walla County, WA (2026)
5 rules for unincorporated Walla Walla County, Washington.
Verified from official government sources
Stormwater Management
Unincorporated Walla Walla County bans dumping anything but stormwater into its storm drainage system or into surface and groundwater under WWCC 11.05.020. The rule lists thirty specific banned contaminants from trash and petroleum products to pesticides and sewage, prohibits illicit connections such as sewage lines tied into storm drains, and is enforced by the county engineer under WWCC Chapter 11.01's civil and criminal penalty procedures.
Walla Walla County Illicit Discharge Ban
Significant RestrictionsWalla Walla County Code § 11.05.020
A.No person shall throw, drain, or otherwise discharge, cause or allow others under their control to throw, drain or otherwise discharge into the storm drainage system and/or surface and groundwaters any materials other than stormwater. ... Examples of prohibited contaminants include but are not limited to the following:1.Trash or debris.2.Construction materials.3.Petroleum products including b...
Erosion Control
Construction sites in unincorporated Walla Walla County disturbing an acre or more, including smaller sites that are part of a larger common plan, must submit a stormwater site plan and pollution prevention plan (SWPPP) under WWCC 11.07.030(C) and obtain the state's construction stormwater general permit. Operators must select and maintain erosion and sediment control best management practices that meet the state's Stormwater Management Manual for Eastern Washington.
Walla Walla County Construction Erosion Control
Some RestrictionsWalla Walla County Code § 11.07.030(C)
C.Construction Site Runoff Control.1.Construction sites disturbing greater than or equal to one acre, including construction sites of less than one acre that are part of a common plan of development or sale that is greater than one acre, shall prepare a stormwater site plan and stormwater pollution prevention plan (SWPPP) in accordance with Chapters 3 and 7 of the SMMEW.a.Construction operators...
Flood Zones
Building or developing land in a mapped special flood hazard area of unincorporated Walla Walla County requires a development permit under Chapter 18.12 of the county code before work begins. New construction must be anchored against flotation and collapse, and new residential structures must have their lowest floor elevated at least one foot above the base flood elevation.
Floodplain Development Rules, Walla Walla County
Significant RestrictionsWalla Walla County Code § 18.12.120(A), § 18.12.190(A), § 18.12.250(A)
A.A development permit shall be obtained before construction or development begins within any area of special flood hazard established in Section 18.12.070. ... A.All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure. ... A.New construction and substantial improvement of any residential structure shall have the lo...
Boat Dock Permits
In unincorporated Walla Walla County, a new dock on a river, lake or other water body is limited to public access, a water-dependent use, or a single-family residence under WWCC 18.08.620(G), and must follow the county's shoreline master program. Docks cannot exceed four feet in width except where documented use patterns justify more, and shared moorage is preferred over new individual docks.
Walla Walla County Boat Dock Permit Standards
Some RestrictionsWalla Walla County Code § 18.08.620(G)
G.New docks shall be permitted only for public access, as an accessory to water-dependent uses or associated with a single-family residence, or as otherwise allowed by the SMP.1.To limit the effects on ecological functions, the number of docks should be limited and new subdivisions should employ shared moorage whenever feasible. Docks on shorelines of the state must comply with policies and reg...
Flood Elevation Requirements
In special flood hazard areas of unincorporated Walla Walla County, new construction and substantial improvement of a residential structure must have its lowest floor, including any basement, elevated to or above one foot above base flood elevation under WWCC 18.12.250(A). Commercial and other nonresidential structures must meet the same one-foot freeboard or be floodproofed to that level under WWCC 18.12.260.
Walla Walla County Flood Elevation Freeboard Rule
Some RestrictionsWalla Walla County Code §§ 18.12.250(A), 18.12.260
18.12.250 - Residential construction. A.New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to or above one foot above base flood elevation. ... 18.12.260 - Nonresidential construction. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the ...
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