Our two field stations facilitate research in the lake districts - the Hasler Laboratory of Limnology on Lake Mendota in the Yahara Lake District of southern Wisconsin and the Trout Lake Station in the Northern Highlands of Wisconsin. Most of our data are public and available through this web site. Most of our long-term data sets date to 1981—when NTL was one of the first six LTER sites funded by the U.S. National Science Foundation, but several originate as early as the 1850s or as late as the mid 1990s. We invite collaboration with others.