As part of the National Atmospheric Deposition Program/National Trends Network (NADP/NTN), precipitation is captured at two sites on GLEES. One site, WY95 (Brooklyn), is located at the Brooklyn Lake monitoring site, and the second site, WY00 (Snowy Range), is located near West Glacier Lake. A paired comparison of the Brooklyn site was operated 1998-1999 for QA/QC and the site is available for further instrumentation evaluation or comparison.

There are about 200 NADP/NTN stations across the United States, Puerto Rico, and American Samoa. Wet deposition is collected continuously at these stations throughout the year, with samples removed between 0900 and 1100 every Tuesday and analyzed locally for pH and conductivity. Samples are then shipped to a central analytical laboratory operated by the Illinois State Water Survey, where they are analyzed for SO4, NO3, Cl, PO4, Na, K, Ca, Mg, NH4, H and reanalyzed for pH and conductivity.

Precipitation amounts at the NADP/NTN sites are collected by a Belfort dual traverse recording rain gage, and through utilization of a weight calculation of the sample. NADP data are available from the network, including the two GLEES sites, at: http://nadp.sws.uiuc.edu .