Great Lakes Mesoscale convective complexs or MCCs can cause damage to wide swaths of forest and shatter glass in city buildings. These storms mainly occur during the night, and the systems sometimes have small embedded tornadoes, but more often straight-line winds accompanied by intense lightning. Historically, the Great Lakes, in addition to their lake ecology, were surrounded by various forest ecoregions (except in a relatively small area of southeast Lake Michigan where savanna or prairie occasionally intruded). Logging, urbanization, and agriculture uses have changed that relationship. In the early 21st century, Lake Superior's shores are 91% forested, Lake Huron 68%, Lake Ontario
Great Lakes Great Lakes-Saint Lawrence River Basin Sustainable Water Resources Agreement and the Great Lakes-St. Lawrence River Basin Water Resources Compact that would prevent most future diversion proposals and all long-distance ones. The agreements strengthen protection against abusive water withdrawal practices within the Great Lakes basin. On December 13, 2005, the Governors and Premiers signed these two agreements, the first of which is between all ten jurisdictions. It is somewhat more detailed and protective, though its legal strength has not yet been tested in court. The second, the Great Lakes Compact, has been approved by the state legislatures of all eight states