tag:digital.library.illinois.edu,2005:/items/9e49ba50-82d4-0134-1f08-0050569601ca-1Illinois (La Salle County), Ottawa quadrangle : topography2022-09-15T18:31:30Ztag:digital.library.illinois.edu,2005:Item/669472016-11-15T17:25:06Z2022-09-15T18:31:30ZIllinois (La Salle County), Ottawa quadrangle : topographyContour interval 20 feet.University of Illinois at Urbana-Champaign Library