McALEER STRATEGIC PLAN, CITIES OF EDMONDS, MOUNTLAKE TERRACE, LYNNWOOD, SHORELINE, AND LAKE FOREST PARK, AND SNOHOMISH COUNTY, WA
Client: City of Edmonds, Edmonds, WA
The City of Edmonds contracted with the a group of consultants, including Clear Creek Solutions, to prepare a strategic action plan that will address issues related to water quantity and water quality within the Lake Ballinger-McAleer Creek drainage basin. The cities of Edmonds, Lake Forest Park, Lynnwood, Mountlake Terrace, and Shoreline together with Snohomish County formed the Watershed Forum to guide the development of the McAleer Strategic Action Plan.
The Strategic Action Plan primarily addressed storm water and surface water flow issues related to the level of Lake Ballinger. Clear Creek Solutions created hydrologic and hydraulic models to evaluate Lake Ballinger flooding based on current land use conditions and past forested conditions. For input to the Watershed Forum's decision-making process Clear Creek Solutions produced memoranda detailing a water balance assessment of the Lake Ballinger drainage area, surface water flow analysis of flows into Lake Ballinger and McAleer Creek downstream flows in Lake Forest Park, mitigation strategies, and an evaluation of flood solution alternatives.
Mitigation strategies included the implementation of low impact development (LID) facilities and practices. LID options available for use in the Lake Ballinger-McAleer Creek watershed included permeable pavement, roof runoff dispersion, green roofs, rain gardens/bioretention, rainwater harvesting, and watershed reforestation. Permeable pavement and roof runoff dispersion onto outwash soils were identified as having the greatest potential for reducing stormwater runoff and increasing groundwater recharge.
Evaluation of flood solution alternatives included the addition of regional stormwater flow control facilities above Lake Ballinger, construction of regional stormwater infiltration facilities above Lake Ballinger, and adding a high flow bypass at the Lake Ballinger outlet (the headwaters of McAleer Creek). Results were presented in terms of the impact on Lake Ballinger lake level elevations and downstream flooding in Lake Forest Park. This information was used by the Watershed Forum to make recommendations on solution strategies to implement in the watershed.