Low Impact Development Integration

Staff Contact

Richard Sawyer
Surface Water Program Manager
(425) 984-6153

Low Impact Development Integration


The City’s Western Washington Phase II Municipal Stormwater Permit (Permit) is issued by the Washington State Department of Ecology (Ecology) as part of the National Pollutant Discharge Elimination System (NPDES) program.  The City has been under Permit coverage since 2007, and is currently under its third permit under Ecology.  Each Permit has built upon requirements and programs developed under the previous Permit.  The current Permit, effective August 1, 2013 through July 31, 2018, requires that the City revise their local development-related code, rules, standards, or other enforceable documents to incorporate and require Low Impact Development (LID) principles and LID Best Management Practices (BMPs).  These revisions must be implemented by December 31, 2016.


LID is a surface water management philosophy that strives to manage surface water at the source through principles such as, but not limited to, 1) retention of native soils, vegetation and trees, 2) reduction of impervious areas and 3) clustering of development away from critical habitat.  In addition to these principles, LID also utilizes an assortment of BMPs to manage surface water in a way that mimics how the predeveloped environment worked.  These BMPs include rain gardens, green roofs, bio-retention facilities and permeable surfaces (including asphalt and concrete pavements, pavers and reinforced vegetated surfaces). 

The City began the process of LID integration with updates to the Surface Water Master Plan and the Surface Water Element of the City’s Comprehensive Plan in 2014 and 2015.  Policy SW 1.1.4 was added to the Surface Water Element which support efforts to make LID the preferred and commonly used approach to site development.  The Surface Water Master Plan developed a programmatic surface water project, labeled ‘Sprog-01’, which is the last part of integrating the Permit’s LID requirements into the City’s codes and standards.

Current Progress

The current phase of LID integration, which began in late 2015/early 2016, included 1) contracting a knowledgeable consultant to assist the City with integration of LID into applicable codes and standards.  The consultant then worked with a committee of staff members to 2) gather all applicable information related to existing development codes and standards and 3) conducted a gap analysis to determine which codes and standards needed amending and which were meeting the intent of LID.  Presently, and moving forward, the consultant is 4) working with staff to develop code amendments for Council and public review.  The final step of the process will include 5) development of an ordinance for Council adoption.  This ordinance would amend applicable codes and standards and adopt the new surface water design manual, meeting compliance with the NPDES municipal stormwater Permit.


To implement this project, the City acquired the services of two environmental engineering firms.  PACE Engineering is the City’s on-call surface water consultant and provides oversight and technical guidance.  AHBL, Inc. has been forefront in developing and implementing LID in the Puget Sound region for many years and was co-author with the Puget Sound Partnership on the region’s primary guidance manual on this topic titled “Integrating LID into Local Codes: A Guidebook for Local Governments”.  AHBL is currently conducting similar efforts for many other local municipalities and is providing the bulk of the review and recommendations that will be presented to Council over the next few meetings.  The City formed a multi-department committee to work with the consultants on this endeavor, which includes planners from Development Services and Planning & Community Development, a Civil Engineer from Public Works and the City’s Surface Water Program Manager. 


Earlier this year, a thorough gap analysis of the City’s existing codes and development standards was conducted.  The gap analysis, which leveraged the Consultant’s expertise and experience working with several other municipalities within the region, identified specific areas in the City’s codes that hindered or prohibited the use of LID principles and BMPs.  It is also worth noting that this gap analysis confirmed that many sections of the City’s code already supported the implementation of LID principles and BMPs.  Once the gap analysis identified areas in the City’s codes and standards needing an update, staff worked with the consultant to begin drafting amendments to eliminate those gaps, which is still in progress and will continue to evolve with Council and public review.  The more substantial updates needed to address gaps include:

  • Updated definitions to include LID terminology

  • Updated landscaping requirements to allow LID where feasible

  • Updated paving surface standards to allow permeable options where feasible

  • Updated impervious area zoning maximums reduced (or established)

  • Road Standards update to include LID requirements

  • Reduce impervious areas where feasible

  • Allow permeable surface options where feasible

  • Allow LID BMPs where feasible

  • 2016 King County Surface Water Design Manual update to include LID requirements

  • Equivalent to Ecology’s Stormwater Management Manual for Western Washington

  • Define LID feasibility and infeasibility

  • Provides permitting and site planning criteria for LID principles and BMPs

  • Provides design and construction criteria for LID principles and BMPs

  • Provides operations and maintenance criteria for LID principles and BMPs



September 2016 – SEPA submittal to City of Kenmore

SEPA Checklist and Application


September 2016 – Department of Commerce submittal

Dept of Commerce Submittal


September 19, 2016 – Council Meeting 1 to introduce LID integration

Council Report


Draft 1 Proposed Gap Analysis

Draft 1 Proposed Code Amendments


September 27, 2016  – Public Open House 1 (10am - 1pm) City Hall Community Room

Draft 1 Proposed Gap Analysis

Draft 1 Proposed Code Amendments


September 29, 2016 – Public Open House 2 (2pm - 4pm) City Hall Community Room

Draft 1 Proposed Gap Analysis

Draft 1 Proposed Code Amendments


October 24, 2016 - Public Open House 3 (4:30pm - 6:30pm) City Hall Community Room

Draft Ordinance (including Draft 2 Proposed Code Amendments)


October 24, 2016 – Council Meeting 2 to present draft ordinance

Council Report

Draft Ordinance (including Draft 2 Proposed Code Amendments)


November 14, 2016 - Public Hearing to present draft ordinance

Draft Ordinance (including Draft 2 Proposed Code Amendments)


November/December, 2016 – Council Meeting 3 Motion to adopt final ordinance

December 31, 2016 – Deadline for implementation of updated codes and standards


Please check back for updates and changes

Last updated: Wed, 12/28/2016 - 12:16pm