Long-Term Ecological Research (LTER)/NTL002: Chemical Limnology of North Temperate Lakes Primary Study Lakes

Special Comments: These measurements are made concurrently with parameters listed in physical (NTL001) and plankton (NTL003) databases. Derived data sets containing epilimnetic averages and hypsometrically weighted averages over depths are also available. The North Temperate Lakes (NTL) site is affiliated with the Center for Limnology at the University of Wisconsin, Madison.

The NTL site focuses its research on north temperate lake ecosystems in the Northern Highland Lakes District of Wisconsin. The Northern Highland Lakes District, has an area of approximately 10,000 sq. km. and has one of the highest concentrations of lakes in the world. Lakes range in size from 0.1 to 1,500 ha, in depth from 1 to 33 m, and in fertility from oligotrophic to eutrophic.

Other representative limnological conditions include: rainwater dominated, groundwater dominated and drainage lakes; dystrophic lakes; lakes with varved sediments, winterkill lakes, temporary and permanent forest ponds, and reservoirs. Lakes are influenced by strong seasonality and are usually ice covered from late November to late April. Lakes within the Northern Highland exhibit near-natural water quality conditions.

Nearly 80% of the land area and two-thirds of the lake frontage are protected.