Tara Williams-Sether 2003 The Level 1.5 method is a limited-detail method that is used for quick estimates of bridge scour. The method was developed by the U.S. Geological Survey in Montana and was used to estimate scour depths at 215 bridge sites located on secondary roads throughout North Dakota. The estimated scour depths are presented in tabular form. application/pdf 10.3133/ofr03134 en Estimated level 1.5 bridge scour at selected sites in North Dakota, 1999-2002 reports