The site has been investigated by The Watershed Company, an environmental consultants who have also worked on Bellevue Botanical Gardens, Lake Chelan State Park, and Tyee Middle School, among many others. They identified a find of Category III wetland located in the southern portion of MICA's proposed lease area. Four categories of wetland are identified in the City of Mercer Island code (Section 19.07.080) with Category I being the most sensitive, and Category IV the least. Much of the wetland is situated on a slope above the skate park, and most of the wetland was filled nearly 50 years ago in the area where Mercerdale lawn is now.
City code (Section 19.07.080) allows for a reduction of buffer zones for Category III wetlands when a critical area study is done with mitigation that results in no net loss of wetland and buffer functions. MICA has worked with The Watershed Company to develop a mitigation plan that proposes a reduction of the buffer to 25 ft and to mitigate this reduction by restoring the ecological function to over 11,000 sq ft of native trees and shrubs and infill plantings. The net effect will be a major improvement to the ecological function and aesthetics of a long-degraded habitat. The mitigation plan will be peer reviewed and is subject to City approval.