Historically, ash tree species made up a significant proportion of the tree canopy in Ozaukee County. Since the arrival of emerald ash borer (EAB) in 2008, the majority of ash trees in Ozaukee County have died. It is estimated that 20% of the total tree canopy in Wisconsin is ash (WDNR), but inventories and field observations have found some woodlands in Ozaukee County to be comprised of 80-90% ash with a 99% mortality rate due to EAB.
The Ozaukee County Planning and Parks Department (Department) has removed over 2,500 EAB-infected ash trees in the Ozaukee County Park System alone and has implemented extensive native tree planting efforts within Ozaukee County Parks and properties, habitat restoration project areas and private lands beyond normal operations to mitigate the loss of ash tree canopy. EAB management plans also exist for several County Parks. Since 2014, the Department has planted nearly 37,000 trees prioritizing locally native species throughout Ozaukee County, the majority within the Ozaukee County Park System. This information is stored in a GIS database managed by the Department. The Department will continue to prioritize the removal of hazardous EAB-infected ash trees and native tree plantings to mitigate the loss of ash due to EAB.