Location Pool Riffle Difference 1 6 3 3 2 6 3 3 3 3 3 0 4 8 4 4 5 5 2 3 6 2 2 0 7 6 2 4 8 7 2 5 9 1 2 -1 10 3 2 1 11 4 3 1 12 5 1 4 13 4 3 1 14 6 2 4 15 4 3 1