Great Lakes are estimated at 900 trillion. The influx of parasitic lamprey populations after the development of the Erie Canal and the much later Welland Canal led to the two federal governments of the US and Canada working on joint proposals to control it. By the mid-1950s, the lake trout populations of Lakes Michigan and Huron were reduced, with the lamprey deemed largely to blame. This led to the launch of the bi-national Great Lakes Fishery Commission. "The Great Lakes: An Environmental Atlas and Resource Book" (1972) noted: "Only pockets remain of the once large commercial fishery." But, water quality improvements realized
Griebnitzsee of lakes towards the Großer Wannsee. The remaining water flows through the Griebnitzsee to its western end, where it flows into the River Havel near Potsdam. The length of the Griebnitzsee is navigable, and forms part of the Teltow Canal route that links the River Havel with the River Spree and the Oder-Spree Canal, bypassing the reach of the River Spree through central Berlin. The navigable Griebnitz Canal provides an alternative link from the Griebnitzsee to the River Havel via the Großer Wannsee. During the time of the Berlin Wall, the border between Berlin and East Germany ran down the