This collaboration is exploring the nitrogen cycle under ice, and nitrogen-oxygen linkages, using long-term data for Wisconsin, USA lakes. Lake biogeochemistry has been sampled in these lakes approximately 2-3 times per winter, for 30+ years. Funding was provided by the National Science Foundation (NSF DEB #1431428, NSF DEB #1136637, PI Stephanie Hampton), North Temperate Lakes Long-term Ecological Research (NTL-LTER) project (NSF DEB-1440297, PI Emily Stanley), and Washington State University. **Selected References** Hampton SE, Galloway AWE, **Powers SM**, Ozersky T, Woo KH, Batt RD, Labou SG, O’Reilly CM, Sharma S, Lottig NR, Stanley EH and others. 2017. Ecology under lake ice. Ecology Letters 20: 98-111 . **Powers SM** and Hampton SE. 2016. Winter limnology as a new frontier. Limnology and Oceanography Bulletin 25: 103-108. Hampton SE, Labou SG, Woo KH, Galloway AWE... **Powers SM** et al. 2016. Winter and summer comparison of biological, chemical, and physical conditions in seasonally ice-covered lakes. KNB Data Repository. doi:10.5063 https://knb.ecoinformatics.org/#view/doi:10.5063/F12V2D1V