Prepared for

The University of Minnesota is committed to the policy that all persons shall have equal access to its programs, facilities, and employment without regard to race, religion, color, sex, national origin, handicap, age or veteran status. ii A physical model study of the intake structure of the Prairie du Sac Hydroelectric Project was conducted to assess the distribution of velocities across the intake as an aid in identifying possible modifications to meet resource agency fish protection criteria. The model was built at a scale of 1 to 14. In the model study, approach velocity characteristics were evaluated for a new trash rack placed upstream of the intake structure replacing the existing trash rack inside the structure. Two modification scenarios were studied: a trash rack with 1.75-inch openings (68 % opening ratio), and a trash rack with 1.0-inch openings (53 % opening ratio). Flow velocities were measured at 40 locations upstream of the model trash rack, corresponding to points located approximately one foot upstream of the trash rack in the full-scale (prototype