Data for the Lakes and Impoundments Drought Index in the Massachusetts Drought Management Plan

The Massachusetts Drought Management Plan (DMP, 2023) uses data from select lake and impoundment systems as an index for drought in six of seven regions in the state. The contents of these lakes and impoundments are reported to Massachusetts Department of Conservation and Recreation (DCR) and classified as one of five levels for drought severity ranging from level 0 (Normal; percentile greater than 30) to level 4 (Emergency; percentile less than 2). Lake and impoundment system data are provided at the end of each month to DCR through multiple agencies as lake levels, volumes, or percent-full (reservoir capacity). USGS reviewed data from 14 of the lake or impoundment systems including 28 waterbodies. Diagrams for each system show the capacity of each waterbody and how water is transported through the systems. This data release provides historical monthly data in volume for each system and historical monthly data in feet for systems that consist of only one waterbody when recorded values were available . From these historical monthly data, the 50th-, 30th-, 20th-, 10th-, and 2nd- percentiles were computed. Stage volume rating data for each waterbody at each system are provided in two formats to convert gage height (feet) to volume (million gallons). The stage volume rating data files are formatted as a text (.txt) table for easy manual reading and the other is a comma-separated value (.csv) column format that is easily loaded into a spreadsheet. Stage volume rating data were provided by the municipalities and agencies that manage the systems or were developed for this study. At one system (Hudson, Gates Pond), no stage volume rating data or bathymetry data were available. A stage volume rating was developed using a python script using maximum depth and a shape file of the pond shoreline. The Python script used to develop the stage volume rating data and the R script used to compute the quantiles are published as a part of this data release. Files for each system include supplied historical volume, computed volume percentiles, stage volume rating(s), and a system diagram. Historical elevation data and computed elevation percentiles are included when applicable.