Anchorage Bowl Basins The image map of the sites selected for the Anchorage Municipality Urban Gradient Study allows the user to click on the portion of the basin of interest. The linked pages are currently under construction and are being actively updated. Please report suggestions or errors to Bob Ourso (rtourso@usgs.gov). This map does not show all watercourses in the Anchorage area. It does show current road coverages.