1. Hydrology and Hydraulics

2. Reservoir Configuration

3. AlternativeCurrent ConditionsFlood StorageMulti-Purpose (Hydropower) Total storage capacity (AF)080,000145,000 Reservoir surface area (ac)NA1,0001,450 Bottom elevation (ft)NA1428.6 Spillway elevation (ft)NA1646.61696.6 Dam crest elevation (ft)NA1666.61716.6 Dam crest length (ft)NA1,4501,800 Outlet capacity (cfs)NA 2,000 Spillway length (ft)NA500 Spillway weir coefficient 1 NA1.11 1 Spillway maximum capacity (cfs)NA49,640 Power plant minimum operating elevation (ft) NA 1606.6 Power plant capacity (cfs)NA 732 Power plant tailwater elevation (ft)NA 1436.6 Table 3 Dam and Outlet Configuration for Alternatives. Notes: 1 The spillway weir coefficient was calculated from the given spillway length and a spillway capacity requirement of 50,000 cfs

4. DatesPower Release (cfs) October 1-November 23140 November 24-March 31732 April 1-September 30140 Table 7 Multi-Purpose Reservoir Power Release Schedule

5. Reservoir Pool Elevation (NGVD + 1,000 ft) Description of Release 1428.6 to 1594.5 20 cfs bypass release No power release 1594.5 to 1606.5 Ramp to 140 cfs bypass release (10 cfs per foot elevation) No power release 1606.6 to 1631.6 No bypass release 140 cfs low power release 592 cfs high power release 1631.6 to 1657.0 Ramp to 1,268 cfs bypass release (50 cfs per foot elevation) 140 cfs low power release 592 cfs high power release 1657.0 to 1716.6 1,268 cfs bypass release 140 cfs low power release 592 cfs high power release Table 8 Multi-Purpose Reservoir Overall Release Schedule (November 24 to March 31)

6. Reservoir Pool Elevation (NGVD + 1000 ft) Description of Release 1428.6 to 1594.5 20 cfs bypass release No power release 1594.5 to 1606.5 Ramp to 140 cfs bypass release (10 cfs per foot elevation) No power release 1606.6 to 1631.6 No bypass release 140 cfs low power release 1631.6 to 1643.4 Ramp to 592 cfs bypass release (50 cfs per foot elevation) 140 cfs low power release 1643.5 No bypass release 140 cfs low power release 592 cfs high power release 1643.5 to 1668.9 Ramp to 1,268 cfs bypass release (50 cfs per foot elevation) 140 cfs low power release 592 cfs high power release 1668.9 to 1716.6 1,268 cfs bypass release 140 cfs low power release 592 cfs high power release Table 9 Multi-Purpose Reservoir Overall Release Schedule (April 1 to November 23)

7. Flood Modeling

8. Figure 3 Reservoir Water Surface Elevation and Outflow – 100-year Event, Flood Storage Alternative

9. Figure 2 Comparison of Flood Storage Alternative to Current Conditions – 100-year Event, USGS Gage at Doty

10. EventEmptying Time (days) 100 year24 50 year21 10 year15 2007 flood50 Table 6 Flood Storage Reservoir Emptying Time after Flood Events Notes: Time is calculated starting from the time when the reservoir begins storing water (reservoir inflow > 2000 cfs) and ending at the time when reservoir outflow is equal to reservoir inflow.

11. Event Peak Flow (cfs) 1-Day Average Flow (cfs) 3-Day Average Flow (cfs) 7-Day Average Flow (cfs) CurrentFloodDiffCurrentFloodDiffCurrentFloodDiffCurrentFloodDiff 100-yr 39,35317,433-55.7%24,33110,914-55.1%13,6647,003-48.7%8,1924,941 - 39.7% 50-yr 32,56214,792-54.6%20,3989,473-53.6%11,8746,348-46.5%7,3444,631 - 36.9% 10-yr 19,8579,831-50.5%12,9376,740-47.9%8,2335,014-39.1%5,4723,941 - 28.0% Dec07 63,10025,861-59.0%41,39017,476-57.8%20,3109,224-54.6%11,3935,798 - 49.1% Table 5 Comparison of Flood Storage and Current Conditions Modeling Results at the USGS Gage at Doty Notes: Current = current conditions alternative Flood = flood storage alternative

12. Figure 14 1996 Flood Hydrograph at Mellen Street

13. Figure 19 1996 Flood Water Surface Elevation Profile, Existing and Proposed

14. Figure 13 100-year Hydrograph at Mellen Street

15. Figure 15 100-year Flood Profile, Existing and Proposed

16. Figure 16 50-year Water Surface Elevation Profile, Existing and Proposed

17. Figure 17 10-year Water Surface Elevation Profile, Existing and Proposed

18. Figure 18 2-year Water Surface Elevation Profile, Existing and Proposed

19. Flow Exceedance Analysis

20. Figure 7 Exceedance Curves for the Flood Storage and Current Conditions Alternatives – USGS Gage at Doty

21. Month Average MaximumMinimum 90% 50%10% Flood Current Flood Current Flood Current Flood Current Flood Current FloodCurrent Oct2232263,9825,77718 24 66 478 Nov1,0081,0287,10213,44422 89 583 2,7312,411 Dec1,3391,36717,22640,33250 248 7967673,0933,103 Jan1,3931,3708,24616,413166 319 1,0099292,9562,933 Feb1,0331,0209,12819,162133 219 658 2,5182,029 Mar8828675,3819,470100 268 645 1,8361,658 Apr585 6,23611,099114 220 392 1,1241,076 May273 2,171 79 113 212 506 Jun161 2,6022,60140 70 121 275 Jul67 387 22 35 60 103 Aug43 662 17 24 34 59 Sept60 2,321 16 21 30 86 Table 10 Comparison of Flood Control and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Doty Notes: Flood = flood storage alternative Current = current conditions alternative

22. Month Average MaximumMinimum 90% 50%10% Flood Current Flood Current Flood Current Flood Current Flood Current FloodCurrent Oct79880014,60516,400181 229 390 1,694 Nov3,9393,96032,66138,400177 473 2,325 10,20310,200 Dec6,1266,15738,79461,900327 1,380 4,1654,03514,09914,400 Jan6,6456,61750,33358,5001,010 1,843 5,2074,99513,20112,990 Feb5,2455,23554,16664,200709 1,482 3,570 10,48610,300 Mar4,2604,24619,90821,900601 1,361 3,235 8,6848,593 Apr3,0043,00734,21538,000670 1,260 2,225 5,313 May1,5331,5317,360 394 706 1,220 2,809 Jun969 5,810 234 437 775 1,641 Jul400 1,340 151 235 361 622 Aug267 2,100 117 177 236 372 Sept344 3,600 128 199 272 457 Table 13 Comparison of Flood Control and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Grand Mound Notes: Flood = flood storage alternative Current = current conditions alternative

23. Month Average MaximumMinimum 90% 50%10% Flood Current Flood Current Flood Current Flood Current Flood Current FloodCurrent Oct 1,055 15,100 282 335 546 2,259 Nov 5,2715,29432,91638,800293 593 3,250 13,84213,800 Dec 8,6328,66045,69367,300538 2,131 6,1005,93519,60420,170 Jan 9,5179,48154,57860,3001,580 2,900 7,6707,37019,27019,190 Feb 7,764 52,37555,0001,180 2,246 5,7905,78016,36016,180 Mar 6,2336,22028,81529,6001,090 2,200 4,945 11,800 Apr 4,3364,34132,01535,8001,120 1,960 3,350 7,270 May 2,2142,2099,570 737 1,030 1,860 3,919 Jun 1,393 7,730 352 680 1,110 2,401 Jul 625 1,810 258 386 568 924 Aug 427 2,580 182 311 407 558 Sept 487 5,160 183 307 403 608 Table 14 Comparison of Flood Control and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Porter Notes: Flood = flood storage alternative Current = current conditions alternative

24. Figure 5 Comparison of Multi-purpose Alternative to Gage Records – USGS Gage at Doty – Water Years 2001 to 2003

25. Figure 6 Reservoir Results for Multi-purpose Alternative – Water Years 2001 to 2003

26. Figure 8 Exceedance Curves for the Multi-purpose and Current Conditions Alternatives – USGS Gage at Doty

27. Month Average MaximumMinimum 90% 50%10% Multi Current Multi Current Multi Current Multi Current Multi Current MultiCurrent Oct 180 226 2,662 5,777 28 18 48 24 117 66 337 478 Nov 756 1,028 6,303 13,444 33 22 104 89 427 583 1,939 2,411 Dec 1,392 1,367 16,393 40,332 105 50 311 248 1,100 767 2,585 3,103 Jan 1,349 1,370 7,092 16,413 198 166 351 319 1,178 929 2,404 2,933 Feb 1,129 1,020 8,795 19,162 179 133 231 219 992 658 1,967 2,029 Mar 933 867 4,478 9,470 153 100 280 268 942 645 1,429 1,658 Apr 416 585 4,479 11,099 164 114 220 321 392 702 1,076 May 296 273 1,045 2,171 168 79 182 113 234 212 501 506 Jun 210 161 1,161 2,601 154 40 165 70 184 121 288 275 Jul 160 67 291 387 90 22 139 35 161 60 178 103 Aug 138 43 338 662 54 17 82 24 152 34 160 59 Sept 123 60 991 2,321 32 16 53 21 122 30 163 86 Table 11 Comparison of Multi-Purpose and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Doty Notes: Multi = multi-purpose alternative Current = current conditions alternative

28. Month Average MaximumMinimum 90% 50%10% Multi Current Multi Current Multi Current Multi Current Multi Current MultiCurrent Oct 76380013,28516,4002111812602294373901,5291,694 Nov 3,6773,96032,50438,4002051774774732,1122,3259,44410,200 Dec 6,1826,15737,96161,9003823271,6051,3804,4054,03513,32614,400 Jan 6,6026,61749,17958,5001,0361,0101,9101,8435,1684,99512,74012,990 Feb 5,3335,23553,83364,2007547091,4881,4823,9063,57010,19310,300 Mar 4,3154,24619,43121,9006546011,3821,3613,5253,2358,2948,593 Apr 2,8423,00732,35638,0007206701,2591,2602,1782,2254,7705,313 May 1,5531,5316,2227,3604833947657061,2681,2202,8302,809 Jun 1,0179695,3955,8103482345264378297751,6481,641 Jul 4924001,2661,340225151335235462361693622 Aug 3632671,7402,100155117253177348236477372 Sept 4083442,6023,600165128247199364272529457 Table 15 Comparison of Multi-Purpose and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Grand Mound Notes: Multi = multi-purpose alternative Current = current conditions alternative

29. Month Average MaximumMinimum 90% 50%10% Multi Current Multi Current Multi Current Multi Current Multi Current MultiCurrent Oct 1,0261,05514,59515,1003022823623355855462,1332,259 Nov 5,0035,29432,35438,8003212936125933,1073,25012,68613,800 Dec 8,6888,66045,50167,3005935382,4412,1316,3395,93519,01620,170 Jan 9,4749,48153,34360,3001,5791,5802,9122,9007,5507,37018,69819,190 Feb 7,8457,76451,40655,0001,2251,1802,2522,2465,9845,78015,70316,180 Mar 6,2926,22028,81529,6001,1421,0902,1822,2005,2274,94511,59111,800 Apr 4,1794,34130,15635,8001,1701,1201,9531,9603,3173,3506,8487,270 May 2,2302,2098,4329,5708187371,0881,0301,8981,8603,8493,919 Jun 1,4401,3937,6807,7304643527756801,1631,1102,3992,401 Jul 7176251,8311,810333258493386666568998924 Aug 5244272,3202,580221182385311522407660558 Sept 5514875,1225,160221183348307494403688608 Table 16 Comparison of Multi-Purpose and Current Conditions Alternatives Monthly Flow Statistics at the USGS Gage at Porter Notes: Multi = multi-purpose alternative Current = current conditions alternative

30. Water Quality/Temperature Modeling

31. Figure 20 Inflow Hydrographs Used at the Upstream Boundary (Doty Gage) for Temperature Modeling

32. Locations of Temperature Probes/Water Quality Data

35. Figure 25 Riverwide flows simulated on July 15, 2010 for the baseline and multi-purpose reservoir scenarios

36. Figure 26 Riverwide flows simulated on August 22, 2010 for the baseline and multi-purpose reservoir scenarios

37. Example of Reservoir Output – CE QUAL 2 Model

38. Calibration of Water Quality Model

45. Number of days Average Water Column Temperature Exceeds 18°C For Various Reaches