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Bathymetry for Muscongus Bay was derived from nine surveys containing109,649 soundings. No surveys were omitted. The average separationbetween soundings was 43 meters. Of the nine surveys used, one dated from1943 and the rest dated from 1944. The total range of soundings was 2.1 metersto -70.4 meters at mean low water. Mean high water values between 2.7 and2.9 meters were assigned to the shoreline. Eighteen points were foundthat were not consistent with the surrounding data. These were removed prior to tinning.DEM grid values outside the shoreline (on land) were assigned null values (-32676).Muscongus Bay has seven 7.5 minute DEMs and two one degree DEMs. The 1degree DEMs were generated from the higher resolution 7.5 minute DEMswhich covered the estuary. A Digital Elevation Model (DEM) contains aseries of elevations ordered from south to north with the order ofthe columns from west to east. The DEM is formatted as one ASCIIheader record (A- record), followed by a series of profile records(B- records) each of which include a short B-record header followedby a series of ASCII integer elevations (typically in units of 1centimeter) per each profile. The last physical record of the DEM isan accuracy record (C-record).The 7.5-minute DEM (30- by 30-m data spacing) is cast on theUniversal Transverse Mercator (UTM) projection. It provides coveragein 7.5- by 7.5-minute blocks. Each product provides the samecoverage as a standard USGS 7.5-minute quadrangle but the DEMcontains over edge data. Coverage is available for many estuaries ofthe contiguous United States but is not complete.