The initial Coords listed will take you to a sign talking about the River Park and how it was founded. On that sign you will see a year mentioned 3 times. Add that year to the number "4641658". Break down the number you just came up with into Coords to get the North Coords. (example 4641658 = N 46 41.658) That will give you the North Coords to the final. To figure out the West Coords, you will need to divide the number "199097319" by how many lots the riverfront banks had been divided among. Convert the number you just found out into Coords and you have your West Coords!
Cache should take less than and hour and is excellent for kids. The final is in park with plenty of picnic tables, toys, and other greats things for kids to do.