Mitigation for the Construction and Operation of Libby Dam

Table 5. Mean bankfull width, depth, width to depth ratio, cross sectional area, and maximum depth for 6 permanent cross sectional
surveys in 1999, 2002 and 2003. Variance estimates for annual mean values are presented in parentheses. A repeated measures analysis
of variance (RPANOVA) was preformed for each parameter, and the P value is presented for each RPANOVA. The results of
subsequent multiple comparisons are also presented.
1999
(Pre
Mean Bankfull Width
(ft)
Mean Bankfull Depth
(ft)
Width to Depth
Ratio
Cross Sectional
Area
(Square ft.)
Maximum Bankfull
Depth (ft)
110.7 (1135.1) 1.26 (0.1) 96.1 (2461.2) 136 (1322) 2.85 (0.8)
Restoration)
2002 (As Built) 53.7 (51.5) 2.06 (0.2) 27.0 (39.8) 114.7 (885.5) 4.67 (2.5)
2003 51.8 (21.0) 2.32 (0.05) 22.5 (8.3) 125 (342.4) 4.73 (1.7)
RPANOVA and P < 0.00001
P < 0.00001
P = 0.001
P = 0.166
Multiple 1999/2002 P = 0.005 1999/2002 P = 0.01 1999/2002 P = 0.016 1999/2002 P = 0.127
Comparison 1999/2003 P = 0.006 1999/2003 P = 0.001 1999/2003 P = 0.014 1999/2003 P = 0.430
Results
2002/2003 P = 0.36 2002/2003 P = 0.093 2002/2003 P = 0.08 2002/2003 P = 0.127
P = 0.003
1999/2002 P = 0.028
1999/2003 P = 0.007
2002/2003 P = 0.799
Table 6. Mean bankfull width, maximum bankfull depth, and length measured from 27 pools in 2002 and 2003. Variance estimates
for annual mean values are presented in parentheses. A statistical comparison of annual mean values was not performed because the
27 pools represented all pools within the project area, and therefore represents a complete census. The percent change for each
parameter from 2002 to 2003 is also presented.
Mean Bankfull Width
(ft)
Maximum Bankfull
Depth (ft)
Mean Length (ft.) Total Length (ft.)
2002 (As Built) 49.5 (18.3) 6.5 (1.1) 64.7 (359.0) 1748.0
2003 53.8 (45.9) 5.6 (1.9) 75.2 (815.4) 2031.2
Percent Change 8.6% -14.8% 16.2% 16.2%
137