Northeast temporal lake water chemistry data compiled from four federally funded programs: RLTM, TIME, HELM, ALPS, 1982-2010

These chemistry data were collected from Maine and Northeast lakes that are part of the Environmental Protection Agency (EPA)’s ongoing Regionalized Long-term Monitoring Program (RLTM), begun in 1982; Temporally Integrated Monitoring of Ecosystems (TIME) program that began in 1999; High Elevation Lake Monitoring (HELM); and completed Aquifer Lakes Project (ALPS). The EPA’s RLTM project began in 1982, expanded to include 16 lakes in 1993, and is ongoing as of 2003. The continuous record of chemical data provides information for regional acid rain assessments. Sampling is done in the spring, summer (stratified conditions, both hypolimnion and epilimnion samples are taken), and fall, just at lake overturn. Companion data for lake inlet and outlet streams have been collected. The TIME project includes lakes across New England and New York to examine changes and trends in aquatic chemistry over time. All samples collected before 1999 in the TIME dataset are from a University of Maine EMAP follow-up study. The ALPS program sampled seepage lakes (no surface inlets) with mapped sand and gravel aquifers that are strongly influenced by precipitation chemistry. The survey was done by the University of Maine in 1986-1987, and 1998-2002, and involved the sampling of 128 lakes. The University of Maine’s HELM project was designed to complement the 1984 Eastern Lakes Survey (ELS) by sampling lakes at an elevation of greater than 600m that had been omitted due to size restrictions. The objective was to highlight lakes that are more susceptible to the effects of acid deposition because they receive higher amounts of precipitation, and their watersheds are less able to neutralize acidic inputs because of steep slopes, shallow soils, and resistant bedrock. In 1986-87 all 90 lakes in Maine at an elevation of 600 meters or higher were sampled. A subset of the original 90 lakes has been sampled since 1997 for logistical and financial reasons. The HELM data set contains chemical data for additional lakes in Baxter State Park (BSP). Most lakes are sampled by helicopter because of their remote locations. Samples were analyzed at the University of Maine laboratory, Plymouth State University, and University of New Hampshire laboratories, using standard methods in place for more than a decade as part of several major Environmental Protection Agency (EPA) projects (see D.V. Peck, M. Morrison, W. Mader, D.J. Chaloud, EPA 600/X-91/080, Rev. 1.01, June, 1993).