Environmental Rules in Issaquah, WA (2026)
5 verified environmental rules for Issaquah, Washington, sourced directly from the municipal code and official government pages.
Verified from official government sources
Stormwater Management
Issaquah bans putting anything but stormwater into the municipal storm drainage system, and it bans illicit connections to the storm drain system, including old ones. IMC 13.28.025 lists 31 prohibited contaminants, and Chapter 13.28 adds annual facility inspections and daily penalties.
Issaquah Stormwater Discharge and Drainage Rules
Significant RestrictionsIssaquah Municipal Code § 13.28.025
A. Prohibited Discharges – Prohibition of Illegal Discharges. No person shall throw, drain, or otherwise discharge, cause or allow others under its control to throw, drain or otherwise discharge into the municipal storm drainage facility and/or surface and groundwaters any materials other than stormwater. Examples of prohibited contaminants include but are not limited to the following: ... 3. P...
Erosion Control
In Issaquah, every land disturbing activity must provide a temporary erosion and sediment control (TESC) plan under IMC 16.26.050(C)(4). Devices go in before construction starts, wet season work from October 1st through April 30th needs the Director's specific approval, and turbidity above 100 NTUs at a monitoring point is a permit violation.
Issaquah Construction Erosion and Sediment Control Rules
Some RestrictionsIssaquah Municipal Code § 16.26.050(C)(4)
4. Temporary Erosion and Sediment Control. All land disturbing activities shall make provisions for temporary erosion and sediment control as follows: a. A temporary erosion and sedimentation control (TESC) plan and associated required documentation shall meet the following requirements: ... vii. ... Clearing and grading may be permitted to continue or to be initiated during the wet season (Oct...
Flood Zones
In Issaquah, no land in an area of special flood hazard can be subdivided, improved, filled, graded or cleared, and no structure built or relocated there, until the responsible person obtains a flood hazard permit under IMC 16.36.100. Development that displaces floodwater needs a Washington-licensed civil engineer's compensatory storage certification, and the Building Official withholds a certificate of occupancy until an elevation certificate is approved.
Issaquah Flood Hazard Permits in Special Flood Hazard Areas
Significant RestrictionsIssaquah Municipal Code § 16.36.100(A)
A. No land within the areas of special flood hazard shall hereafter be subdivided or short subdivided, improved, filled, graded or cleared; nor shall any structure or development, including manufactured homes, be constructed, reconstructed, improved, relocated, or erected on such lands unless the person(s) responsible for such improvements shall first obtain a flood hazard permit for such acti...
Vehicle Idling Restrictions
Issaquah prints no minute count for idling. The one idling rule in the Issaquah Municipal Code sits in the contractor code of conduct at IMC 16.01.020(C): construction equipment will not be left idling unless idling is required for successful operation of the equipment or successful completion of the task.
Issaquah Construction Equipment Idling Rule (IMC 16.01.020)
Light RestrictionsIssaquah Municipal Code § 16.01.020(A), (C)
A. Hours of construction shall be as set forth in IMC 16.35.010 . This means that construction will not begin before 7:00 a.m. and is only allowed between the hours of 7:00 a.m. and 6:00 p.m. on weekdays. No construction activity is permitted on weekends or weekdays that are legal holidays (unless authorized by an extended work hours permit), as observed by State law and defined in RCW 1.16.050...
Flood Elevation Requirements
Issaquah sets its freeboard through the flood protection elevation defined in IMC 16.36.030: 2 feet above base flood elevation in Zones AE and AH and 3 feet in Zone A for residential and inhabited structures, and 1 foot above in Zones AE, AH and A for other uses. IMC 16.36.130 requires the lowest floor and utilities at or above that level.
Issaquah Flood Protection Elevation and Freeboard Requirements
Some RestrictionsIssaquah Municipal Code § 16.36.030
“Flood protection elevation” means an elevation that is defined by the area of special flood hazard designation, as depicted on the FEMA flood insurance rate map (FIRM) and the Issaquah Creek Basin and Nonpoint Action Plan. The flood protection elevation is as follows for the listed activity and related zone designation: ... 2. For residential and inhabited structures (to include manufactured h...
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