Reciprocal Traffic Mitigation Agreements, Forms & Information

Interlocal Agreements (Reciprocal Traffic Mitigation)

Snohomish County has Interlocal Agreements (ILA’s) with the Washington State Department of Transportation (WSDOT) and numerous cities related to mitigation of traffic impacts from new developments. The agreement with WSDOT provides for the mitigation of traffic impacts to state highways caused by traffic generated from new developments in the unincorporated county. The agreements with the cities are ‘reciprocal’ in that they provide for mitigation of impacts on city streets from county developments and mitigation of impacts on county roads from city developments. View links below to the interlocal agreements and supporting forms and documents.

Generic "Offer" Forms

Applicants use these forms to make the appropriate mitigation offers to the City or the County.

Agreements, Forms & Information for Each Individual City



Gold Bar

Granite Falls


Mill Creek



The original Agreement was amended effective August 7, 2019 and is now in effect until December 31, 2029. The amendment modified Sub-sections 3.5, 3.6, 4.5, 4.6, and Section XII. All other sections of the original Agreement are still in effect.  

Effective August 3, 2009



Washington State Department of Transportation

Traffic Study Tools & Information for Developers & Traffic Consultants

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