Funny, I googled for it and only got hits for "Seche - The World's Finest Top Coat", "SECHE - Sioux Empire Christian Home Educators", translations of the French word sèche, seche.net blogfolio...only after googling "seche lakes" did I get any hits---two. The first of which used the spelling "seiche" 54 times and "seche" once. I do believe that qualifies as a typo.

Anyways, wikiing "seche" won't even get you a helpful pointer in the right direction. So for those, like me, who wanted to know what one of those things was, Wikipedia's got a good page on it under "seiche".