Zone 4 Line A Preliminary Suspended Sediment Load Estimates HY08 Rand Eads RiverMetrics LLC Sources Pathways and Loadings Workgroup December 8, 2008 Item # 2b

Zone 4 Line A HY07 11/10/06 – 4/30/07 Rainfall in. 21 storms Max Q 308 cfs Total Q 33,400 cfs 84 SSC analyzed Max SSC 2,744 mg/L Max turbidity 1590 TU Est. load MT HY08 1/31/08 – 6/11/08 Rainfall 2.11 in. 18 storms Max Q 241 cfs Total Q 22,900 cfs 66 SSC analyzed Max SSC 2,095 mg/L Max turbidity 892 TU Est. load 94.7MT Item # 2b

Changes in Data Collection Methods from HY07 to HY08 Bed-mounted boom provided complete data record for season Turbidity sensor and sampler intake at depth-proportional sampling position Improved debris shedding Possible increase in sand to fine ratio Item # 2b

r 2 = 0.89 r 2 = 0.90 r 2 = 0.89 Item # 2b

0.14

Item # 2b 0.12

Item # 2b 0.38

Item # 2b 0.12

Storms account for ~95% of the seasonal load Item # 2b

Zone 4 Sampling HY09 9 rising turbidity thresholds ( ) 6 falling turbidity thresholds (925 – 100) Early season contaminate rising thresholds: 105, 319, 670, 970 Mid season contaminate rising thresholds: 72, 220, 462, 670 Item # 2b