There are at least two types of liability for the owner of contaminated property (cleanup and due care)
The way to eliminate liability for CLEANUP is to perform the necessary inquiry. "EPA's new "All Appropriate Inquiry" rule, which goes into effect November 1, 2006 will elimiate liability for those puchasing contaminated property provided that they retain an environmental professional and complete the necessary process. The rules are created to allow the redevelopment of contaminated properties. Many if not all States have their own laws that preceeded the Federal Amendment to CERCLA (Superfund). The first step is to complete the Environmental Site Assessment (approximately $1,500 to $2,000). This report would likely conclude that sampling is necessary to assess water/sediments/soil for contaminants. The sampling and additional reporting could run another $5,000 to $10,000.
The second type of liability on contaminated sites is commonly called DUE CARE. This is the responsibility of the property owner to protect the public from unacceptable exposures. While a new owner may not have cleanup liability it is their responsibility to manage the property in such a way that the conditions are not exacerbated or create exposure hazards. This is not typically a problem on an urban site where a new building/parking lot will form a seal and create a physical barrier that prevents exposures. The owner generally just needs to notify contractors of the hazard and manage any soil or groundwater that is disturbed.
If the lake you are looking at is indeed contaminated, I could see "due care" requiring that you undertake measures to prevent contact with the water, sediments, fish, etc. This includes trespassers and could actually be extended to wildlife. In addition, it is likely that any dredge material removed from the lake would need to be tested and disposed in a landfill.
Most of the brownfield work that I do is paid by state and federal dollars that are available to local governments in order to encourage redevelopment. The buyer generally doesn't pay the bill. If local brownfield dollars were available, maybe you could end up with a clean lake for the cost of managing the project. This is unlikely because generally funding is based on the creation of new jobs and future tax revenue, which does not appear to be in the future of this property.
