The Spokane River has degraded water quality from heavy metals, in part from historic mining in the Coeur d'Alene River watershed. In May 1999, Ecology began the process of trying to stop further pollution of the Spokane River. It began with testing for metals that were in the river because of the historical mining practices in the Coeur d’Alene Basin in Idaho, which is now a designated federal Superfund site. Testing was followed with cleanup of beaches along the river where the metals had settled out in amounts high enough to threaten human health. While several areas have already been cleaned up, more cleanups are planned. Past mining is not the only source of polluting metals. Water that runs off tires, for example, contains the metal zinc. When this water makes its way to the river, it can contaminate surface and ground waters.