1 Overview of South Yuba River Hydrology Bob Center Presented to FERC Academy on December 10, 2005

2 South Yuba River, Edwards Crossing, May 20, 2005, 14,000 cfs

3 Introduction The FERC re-licensing process has as a primary concern some re-allocation of South Yuba River watershed runoff. At the heart of any new license will be a specification of how much water is to be returned to the rivers and creeks, water temperature, and how the water is to be distributed through time. An understanding of the runoff that is to be the object of this re-allocation will improve understanding of possibilities and constraints, and can assist in articulating interests in discussions with other stakeholders This presentation will provide an overview of runoff in the South Yuba watershed in basic terms: –How much runoff there is, where it comes from, and when, and where it goes –The great variability of precipitation and runoff on all time scales –How dams and diversions impact the rivers and creeks in terms of reduction in volume, continuity and variability First is an overview of runoff in the watershed as a whole, including the over-all effects of dams and diversions Next is a look at the impact that dams and diversions have on: –Middle Yuba River –Canyon Creek –Fordyce Creek –South Yuba above Spaulding Reservoir –South Yuba below Spaulding Reservoir

4 Major Streams, Reservoirs and Conduits in the South Yuba Watershed Weber Peak 8092 Castle Peak 9103 Black Buttes 8030 S. Yuba Fordyce Poor Man M. Yuba S. Yuba Canal Canyon Drum Canal + Mt Lincoln 8382 L Spaulding Jackson Meadows Res Fordyce L Milton Res Bowman L Milton - Bowman Canal Bowman - Spaulding Canal Scotchman Jefferson Humbug Spring Rock Englebright Res Washington Shady Kentucky Owl Rush South Yuba Watershed

5 S Yuba River Fordyce S Yuba River Poorman Creek 50 Pre-Development South Yuba River Basin Hydrology vs Current Hydrology (Data from USGS 1999 Hydrological Data Report) Jones Bar (Hwy 49) Note that many creeks enter the river below Poorman Creek, adding about 140,000 af, mostly from rain. Creek Canyon Creek Today’s Flow Additional flow were there no diversions Average Recorded Yearly Flow (‘000s of acre feet) Yearly flow estimate (‘000s of acre feet) Flow Scale: ¼” = 100,000 acre feet / year

6 Runoff above Lake Spaulding 530,000 af / yr (Includes 158,000 af from Bowman- Spaulding canal, which include 62,000 af from the Middle Yuba) South Yuba River 93,000 af / yr South Yuba Canal 62,000 af / yr Drum Canal 375,000 af / yr Release to River Late Spring Spill 85,000 af /yr* Lake Spaulding Lake Spaulding Stores and Distributes Upper South Yuba River Water (Data from USGS 1999 Hydrological Data Report)

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10 Middle Yuba River and Milton Bowman Canal Weber Peak 8092 Castle Peak 9103 Black Buttes 8030 S. Yuba Fordyce Cr Poor Man Cr M. Yuba S. Yuba Canal Canyon Cr Drum Canal + Mt Lincoln 8382 L Spaulding Jackson Meadows Res Fordyce L Milton Res Bowman Res Milton - Bowman Canal Bowman - Spaulding Canal Hwy 49 (Jones Bar)

11 Impact of Jackson Meadows Reservoir, Milton Dam and Milton-Bowman Canal on Flow Volume on the Middle Yuba River Note: “Pre Dev” means that the data represents the flow before the construction of the dams and diversions immediately upstream (calculated using the equation “Input – Output = Change in Storage”). The date range “71-04” gives the time period covered by the data used in the continuity calculation. Where a date range appears by itself, such as “’88-’04”, the data represents post-development gauge readings, in this case below Milton Dam.

12 Impact of Jackson Meadows Reservoir, Milton Dam and Milton-Bowman Diversion on Flow Volume and Variability in the Middle Yuba River

13 Bowman Reservoir, Bowman-Spaulding Canal, and Canyon Creek Weber Peak 8092 Castle Peak 9103 Black Buttes 8030 S. Yuba Fordyce Cr Poor Man Cr M. Yuba S. Yuba Canal Canyon Cr Drum Canal + Mt Lincoln 8382 L Spaulding Jackson Meadows Res Fordyce L Milton Res Bowman Res Milton - Bowman Canal Bowman - Spaulding Canal Hwy 49 (Jones Bar)

14 Impact of Bowman Reservoir and the Bowman- Spaulding Canal on Flow Volume In Canyon Creek

15 Impact of Bowman Reservoir and Bowman-Spaulding Canal on Flow Volume and Variability In Canyon Creek

16 Fordyce Lake and Fordyce Creek Weber Peak 8092 Castle Peak 9103 Black Buttes 8030 S. Yuba Fordyce Cr Poor Man Cr M. Yuba S. Yuba Canal Canyon Cr Drum Canal + Mt Lincoln 8382 L Spaulding Jackson Meadows Res Fordyce L Milton Res Bowman Res Milton - Bowman Canal Bowman - Spaulding Canal Hwy 49 (Jones Bar)

17 Impact of Fordyce Lake on Flow Timing In Fordyce Creek

18 Impact of Fordyce Lake on Variability In Fordyce Creek

19 South Yuba River above Lake Spaulding Weber Peak 8092 Castle Peak 9103 Black Buttes 8030 S. Yuba Fordyce Cr Poor Man Cr M. Yuba S. Yuba Canal Canyon Cr Drum Canal + Mt Lincoln 8382 L Spaulding Jackson Meadows Res Fordyce L Milton Res Bowman Res Milton - Bowman Canal Bowman - Spaulding Canal Hwy 49 (Jones Bar)

20 The South Yuba above Lake Spaulding

21 Lake Spaulding, the Drum Canal,the South Yuba Canal and the South Yuba River Weber Peak 8092 Castle Peak 9103 Black Buttes 8030 S. Yuba Fordyce Cr Poor Man Cr M. Yuba S. Yuba Canal Canyon Cr Drum Canal + Mt Lincoln 8382 L Spaulding Jackson Meadows Res Fordyce L Milton Res Bowman Res Milton - Bowman Canal Bowman - Spaulding Canal Hwy 49 (Jones Bar)

22 Lake Spaulding, the Drum Canal,the South Yuba Canal and the South Yuba River

23 The South Yuba canyon between Fordyce Lake and Englebright Lake produces a large volume of unimpaired runoff. Accretion from 44 miles of the South Yuba, 9 miles of Canyon Creek below Bowman L, 12 miles of Poorman Creek and numerous smaller creeks creates a “new” river with substantial natural flow and significant natural variability at all scales.

24 In this late season rain and rain-on-snow event, dams on the Yuba attenuate the river’s response when compared to the North American, a similar river (View at 200% to see labels)

25 Spring snowmelt causes daily variation in flow. Enough snowmelt escapes dams to provide some daily variation on the South Yuba (View at 200% to see labels)