The city-owned parcels of the lakefront were created during the late 1880s to the early 1900s by the placement of wood wastes, soil, sand, and demolition wastes into Chequamegon Bay. During the operation of the MGP, residual coal tars and oils were produced as a by-product from the manufacture of natural gas from coal. Records indicate that the residual MGP wastes such as coal tar and oils were discharged with the waste water. This ravine also contains cinders ash, boiler slag, and demolition debris. Just north of the ravine is a seep where water, oils and tar flow to the land surface.
Historic drawings refer to a waste tar dump between the seep area and waste water treatment plant.
In 1989, the city of Ashland performed an investigation on the Kreher Park area for possible expansion of the existing wastewater treatment facility. The discovery of contamination from what was believed to be creosote wastes in the subsoils and ground water at Kreher Park prompted the city to abandon the project. Soil borings and ground water samples indicated elevated levels of hazardous substances. Disturbance of these sediments releases oils and tars to the water column and surface, causing a slick to form on the water surface. In 1995 and 1999, NSP conducted investigations that further defined the area of contamination and confirmed the presence of VOCs associated with coal tar wastes.