Superfund Site: CEDAR CREEK

Superfund Site Profile

Some Key Technical Documents:

Action Memorandum (54 pp, 10.43 MB) May 2016

Administrative Order on Consent (40 pp, 2.41 MB) May 2016

Remedial Investigation Report (833 pp, 118.33 MB) May 2012

Record of Decision (107 pp, 21.43 MB) March 2008

Other site-related documents, at Cedar Creek Superfund Site's Administrative Record.


The Cedar Creek site is in the historic city and township of Cedarburg (Ozaukee County) in southeastern Wisconsin in a suburban residential area north of Milwaukee. The entire site consists of Mercury Marine's Plant 2 and the segment of Cedar Creek from below the Ruck Pond dam to the point where it meets the Milwaukee River. This segment includes open stretches of creek as well as areas known as Columbia Pond, Wire and Nail Pond, and the former Hamilton Pond for a total of 5.1 creek miles. The Milwaukee River is currently not part of the Cedar Creek site and is under the jurisdiction of the Wisconsin Department of Natural Resources. For EPA to address the contamination in the Milwaukee River, WDNR needs to propose and list it under the Agency's National Priorities List as a separate Superfund site. Or, WDNR could work on the river under its own Natural Resources Trustee authority. Exit EPA Disclaimer

PCBs from boat manufacturer Mercury Marine contaminated Cedar Creek and the Plant 2 property. It operated a plant on St. John Avenue from 1951 to 1982. Fluids, containing PCBs, leaked from equipment and were washed into floor drains. These drains emptied into storm sewers. Those sewers emptied into Ruck Pond on the creek and flowed into the Milwaukee River.

Mercury Marine's Plant 2 building was demolished in May 2005. The building, which was in poor condition, also contained PCB contamination. An investigation and feasibility study outlining possible cleanup options was completed in October 2007. A decision on how to clean up Plant 2 was made in March 2008.

Another likely source of contamination in the area was Amcast, a former local automotive industry supplier in Cedarburg. It also had a plant that may have emptied PCBs into the creek via storm sewers. One of them apparently emptied into Hamilton Pond, upstream of Green Bay Road. Due to heavy rains and high creek flow in 1996, the Hamilton Dam collapsed and was removed. The pond was drained leaving behind several acres of mud flats containing PCBs.

Sewers near the Amcast plant and soil under the building were sampled in November 2005. Since Amcast had filed for bankruptcy, its contractor was told to stop working and the results were never analyzed. Soil samples were also taken on private properties near the Amcast plant in summer 2005. Some of those samples showed PCB contamination slightly above what EPA considers to be safe levels.

Since the company is bankrupt, the Amcast portion of the project was separated from Cedar Creek in 2009. EPA is using Superfund money to address the contamination at and near the Amcast Industrial Corp. site.