Lake Huron is basically an oligotrophic lake, although it has at least one problem in common with the other Great Lakes: it is noticeably impacted by contaminants. In the past, phosphorus, DDT, and mercury were the primary contaminants of concern because of the stimulation of nuisance algae growth, the negative impact on raptors, and the tainting of fish for human consumption, respectively. Responses to these discoveries have been control of the point sources of mercury and phosphorus and a ban on DDT production. For Lake Huron, these controls appear to have been effective in curbing mercury releases but not in reducing mercury levels in fish. The controls appear to be beginning to be effective for phosphorus.