MIDAS stands for
Maine Information Display Analys System and a unique MIDAS string identifier is assigned to all of Maine's inland water.
Every time I try to find this metadata I end up spending way too much time, so I am making this available mostly to help me keep my sanity, but it may help others as well.
Geometry: POINT (EPSG:4326) — lake/pond/etc centroid
name (lake/pond/etc name; <chr>),
midas (MIDAS identifier; <chr>)
shp/: ESRI Shapefile (POINT geom)
midas.csv: Plain ol' CSV with X & Y
midas.geojson: GeoJSON (POINT geom)
midas.sqlite: Spatial-ops compatible SQLite;
midastable (POINT geom)