1. Zone 4 Line A Preliminary Suspended Sediment Load Estimates HY08 Rand Eads RiverMetrics LLC www.rivermetrics.com rivermetrics@gmail.com 503-435-7516 Sources Pathways and Loadings Workgroup December 8, 2008 Item # 2b

2. Zone 4 Line A HY07 11/10/06 – 4/30/07 Rainfall 10.38 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 139.6 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

3. 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

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

8. 0.14

9. Item # 2b 0.12

10. Item # 2b 0.38

11. Item # 2b 0.12

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

15. Zone 4 Sampling HY09 9 rising turbidity thresholds (50 - 970) 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