GLERL Great Lakes Monthly Hydrologic Data (1860-Recent)


Accurate hydrologic data (over-lake precipitation, runoff, lake evaporation, net basin supplies, connecting channel flows, diversion flows, beginning-of-month lake levels, and changes in storage) are required for simulation, forecasting, and water resource studies on the Laurentian Great Lakes and their basins. These data are derived from meteorological and hydrological data. The 1993 reference is an update of the earlier report describing Great Lakes monthly hydrologic data. It was expanded and revised to include all available data through 1990 and to reflect improved computational techniques. The raw data utilized were collected from several sources, so the periods of record for each lake vary.

While most of these data are available in the referenced reports, some of the data are not included in the report. These data may be available directly from GLERL. Daily values of some of these parameters may also be available from GLERL on a limited basis.

These data were derived from quality controlled input data (see reference) and are periodically updated to reflect additional data and to extend the period of record. Note that missing data in the *.CIS files is denoted by -9999. This only occurs in December of the last year.

Coverage includes Lake Superior, Lake Michigan, Lake Huron, Lake Erie, Lake Ontario, and Lake St.Clair.

Note: The period of record for the files is dynamic, based on data availability. Most are updated to within the most recent one to two years. The files are presented in Excel spreadsheet format.

Data access


Hunter, T.S., A.H. Clites, A.D. Gronewold, and K.B. Campbell. Development and application of a North American Great Lakes hydrometeorological database - Part I: Precipitation, evaporation, runoff, and air temperature. Journal of Great Lakes Research 41(1):65-77 (DOI:10.1016/j.jglr.2014.4.12.006) (2015).

Hunter, T. S. and T. E. Croley, II, Great Lakes Monthly Hydrologic Data, NOAA Data Report ERL GLERL, National Technical Information Service,Springfield, Virginia, 22161, 1993.

Quinn, F. H. and R. N. Kelley, Great Lakes Monthly Hydrologic Data. NOAA Data Report ERL GLERL-26, National Technical Information Service, Springfield, Virginia, 22161, 1983.


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