Otters are protected in the United States under the Endangered Species Act. This is because the conditions in which they dwell are readily jeopardized, which might result in a considerable fall in their numbers in a short period of time. River otters were once widely distributed across North America, but now survive only in small populations on the Atlantic coast and in the Great Lakes region. There are three types of protection afforded to otters: conservation, management, and research. They are protected as a "threatened" species under the U.S. Endangered Species Act (ESA). This means that if an action cannot be taken to improve the situation for the otter, then it must be allowed to continue in the status quo. Otherwise, the otter would become "endangered". The ESA requires that federal agencies consider the effect any action they take may have on threatened or endangered species. If an agency finds that an action will affect such a species, they must try to find ways to minimize the impact or risk of that action. For example, if an agency knows that taking certain actions will likely lead to the death of an otter, they would avoid taking those actions if possible or would at least make sure that someone is available at all times to provide rescue assistance if needed.