The Environmental Protection Agency’s Regionalized Long-Term Monitoring (RLTM), Temporally Integrated Monitoring of Ecosystems (TIME), and High Elevation Lakes (HELM) projects began prior to implementation of the U.S. Clean Air Act Amendments. The projects documented first the effects of acidic deposition and then changes in geochemistry as acidic inputs have declined. The 30 years of long-term data support U.S. EPA acid rain assessments. Newly-funded UMaine research is using data from these lakes to assess the effects of extreme events on surface waters and changes in dissolved organic carbon through time. Long-term funding has been through U.S. EPA and USGS; HELM and ALPS projects also received funding from the Maine Department of Environmental Protection. University of New Hampshire professor William McDowell is the lead PI; the UMaine lead PI is Sarah Nelson, with Co-PI Jasmine Saros.

 Recent publications:

Sanclements, M., G. Oelsner, D. McKnight, S.J. Nelson, J. Stoddard, 2012. New insights into the source of decadal increases of dissolved organic matter (DOM) in acid-sensitive lakes of the northeastern U.S. Environmental Science and Technology,  DOI: 10.1007/s11356-009-0176-7

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