Water-Year Summaries

Summary table of water allocations and flow releases

Water Year Forecast Water Year Type Actual Water Year Type Restoration Water Allocation Actual Restoration Release Safety of Dams Releases From Lewiston
Ceremonial Releases Other Releases Total Release to Trinity River Peak Release Magnitude Total Diversion thru Carr Tunnels Natural Inflow to Trinity and Lewiston Reservoirs Notes
(acre-feet) (acre-feet) (acre-feet) (acre-feet) (acre-feet) (acre-feet) (cfs) (acre-feet) (acre-feet)
[G] [I] [A] [A,B] [A,B] [A,B] [A] [A] [C] [C,F,I,J]
2001 Dry Dry 369,000 379,600 4,200 383,800 1,760 669,400 818,200 [E]
2002 Normal Normal 470,000 482,700 482,700 6,040 629,000 1,293,500 [E]
2003 Wet Wet 453,000 448,100 68,300 5,700 34,000 556,100 2,610 857,600 1,868,900 [E]
2004 Wet Wet 647,000 651,000 81,100 36,200 768,300 6,200 987,500 1,512,000 [E]
2005 Normal Wet 647,000 647,600 3,600 651,200 6,970 466,700 1,476,000 [H]
2006 Ex. Wet Ex. Wet 815,000 809,900 406,300 1,216,200 10,100 1,350,600 2,496,300 [H]
2007 Dry Dry 453,000 453,700 4,100 457,800 4,750 614,400 752,400 [H]
2008 Normal Dry 647,000 648,700 648,700 6,470 555,000 874,900 [H]
2009 Dry Dry 453,000 445,500 11,100 456,600 4,410 539,200 834,500 [H]
2010 Normal Wet 647,000 656,700 656,700 6,840 274,700 1,602,200 [H]
2011 Wet Wet 701,000 721,800 10,800 732,600 11,600 473,100 1,883,000 [H,J]
2012 Normal Normal 647,000 647,100 39,000 686,100 6,080 709,900 1,075,400 [H]
2013 Dry Dry 453,000 451,900 10,000 18,600 480,500 4,420 852,200 853,100 [H]
2014 Crit. Dry Crit. Dry 369,000 370,500 64,800 435,300 3,410 618,600 396,200 [H]
2015 Dry Dry 453,000 450,700 9,300 47,900 508,000 8,500 450,500 899,800 [H]
2016 Wet Wet 701,000 708,800 39,200 748,000 10,000 278,900 1,458,400 [H]
TOTAL 8,925,000 8,974,300 555,700 58,800 279,700 9,868,600 10,327,300 20,094,800
Notes: All water volume values are rounded to the nearest 100 acre-feet.
A – Computed from daily average flow record reported by the US Geological Survey for the Trinity River at Lewiston Streamgage # 11525500.
The accuracy of the flow records ranges from +/- 5 percent to +/- 15 percent on a time variable basis.
B – Volume estimate for flows above the summer or winter baseflow release for restoration.
C – Computed from daily average record provided by the Bureau of Reclamation. Reported negative daily inflow values included “as is” in calculations.
D – Water allocation prior to implementation of the 2000 Trinity River Mainstem Fishery Restoration Record of Decision.
E – Water allocation limited by Court order 2001-2004. Court ordered volumes varied by year.
F – Long-term average annual inflow to Trinity Reservoir (acre-feet/year) from 1911-2007 as provided by the Bureau of Reclamation = 1,254,000
G – Water year type based on the April forecast (50% exceedence) from the Bulletin 120 – Water Conditions in California.
by the California Department of Water Resources
H – Restoration water allocation as prescribed by the Trinity River Mainstem Fishery Restoration 2000 Record of Decision.
I – The Full Natural Flow is computed by multiplying estimated inflow to Trinity Reservoir by 1.04 to account for the local watershed area between Trinity Dam and the Lewiston Streamgage. The estimated inflow to Trinity Reservoir is computed by the Bureau of Reclamation based on changes in reservoir storage, evaporation, and dam releases. Uncertainty in the reservoir storage and evaporation estimates can lead to negative inflow values being reported. Negative inflow values are erroneous and have been excluded from the calculation of the full natural flow.
J – Beginning in WY2011 the Full Natural Flow at Lewiston is sourced from the California Department of Water Resources; current Full Natural Flow status is at http://cdec.water.ca.gov/cgi-progs/stages/FLOWOUT.