A new dataset for the Santiam River in Oregon, published by the U.S. Geological Survey, provides a highly detailed underwater 3D elevation map that will help support fish habitat restoration and flood modeling work.  The work was done as part of the USGS 3D Elevation Program, known as 3DEP, which uses a next-generation mapping technology to obtain highly detailed three-dimensional elevation information about the natural and constructed landscapes of the Nation, including surfaces under rivers and other inland waterbodies. Known as topobathymetric lidar, the technology uses laser pulses that penetrate water to provide accurate measurements of both the riverbed and the surrounding topography. The data are essential for understanding river dynamics, aquatic habitat conditions and flood risk. It will also be used to develop models of habitat availability for salmon and steelhead and other fish species in relation to river flow below Willamette Valley system dams.