Long awaited Auburn Ravine flow study released; supports need to retrofit Hemphill and Gold Hill Dams
THIS IS AT THE HEART OF THE RECENTLY PUBLISHED, LONG AWAITED FLOW STUDY ON AUBURN RAVINE BY CDF.
Nevada Irrigation District (NID) continues to stubbornly maintains without proof that a non-existent waterfall, which it has christened Chapman Falls, blocks anadromous fishes from getting up Auburn Ravine.
Even without NID retrofitting the Hemphill and Gold Hill Dams, which by law it must do, during high water incidents like 2012, and since Gold Hill Dam was installed in the 1850’s with many high water events, anadromous fishes, steelhead (endangered) and chinook (threatened), have been getting over these barriers, providing a vibrant residence for them all the way upstream to Wise Powerhouse, one mile downstream from the City of Auburn.
How can NID’s mythic Chapman Falls be a barrier when anadromous fish are already in Auburn Ravine all the way to Wise Powerhouse?
On March 19, 1998, the National Marine Fisheries Service (NMFS) listed the Central Valley steelhead distinct population segment (DPS) as a threatened species (63 FR 13347 (1998)). On September 8, 2000, pursuant to a July 10, 2000 rule issued by NMFS under Section 4(d) of the ESA (16 USC § 1533(d)), the take restrictions that apply statutorily to endangered species began to apply to Central Valley steelhead (65 FR 42421 (2000)). On January 5, 2006, NMFS reaffirmed the threatened status of the Central Valley steelhead DPS (71 FR 834 (2006)). NMFS designated critical habitat for Central Valley steelhead on
September 2, 2005 (70 FR 52488 (September 2, 2005)). The critical habitat designation includes the Auburn Hydrologic Sub-area of American River Hydrologic Unit 5514, which encompasses Auburn Ravine (70 FR 52488 (September 2, 2005)).
Central Valley FRCS (Fall Run Chinook Salmon) (Fall Run Chinook Salmon) is classified as a California State Species of Special Concern. At the federal level, it is considered a Species of Concern under ESA (69 FR 19975 (April 15, 2004)). Auburn Ravine is considered to be essential fish habitat (EFH) for Central Valley FRCS (Fall Run Chinook Salmon) (October 15, 2008 73 FR 60987).
Although there are more recent accounts of Chinook (O. tshawytscha) in Auburn Ravine, there were well documented runs in the west Placer streams area – including Auburn Ravine – during the 1960s.
According to California Department of Fish and Game Marine Resources Administrative Report No. 65-2 (DFG 1965), there was an estimated run of 1,000 fall-run Chinook salmon (FRCS (Fall Run Chinook Salmon) in the west Placer creeks area, including: Secret Ravine, Miners Ravine, Antelope Creek, Auburn Ravine, Doty Ravine, andCoon Creek.
The report states that “The run in Secret Ravine and Auburn Ravine was greater than in 1963; the other streams were about the same” indicating that previous runs occurred in these creeks.
CDFW conducted fish surveys in Auburn Ravine in 2004 and 2005. Steelhead trout (Oncorhynchus mykiss) dominated the catch in both years. Relative steelhead trout abundance estimates averaged 2,163 individuals per river mile (RM). At the uppermost survey site, located near Wise Road at approximately RM) 27.5, steelhead trout relative abundance was 337 individuals per RM. Later surveys also documented another anadromous species – Pacific lamprey (Lampetra tridentata) – in Auburn
Auburn Ravine Instream Flow Study CDFW Page 6
Ravine up to at least Bridge Lane (~RM 21) (CDFG 2008). More recently, CDFW staff observed and documented distribution of FRCS (Fall Run Chinook Salmon) (Fall Run Chinook Salmon) during their 2012 surveys (Hoobler and Mulloy 2012).
The reach of Auburn Ravine below the Wise Powerhouse is approximately 27 miles long and extends down to East Side Canal. During the Drum-Spaulding Hydroelectric Project relicensing, PG&E designated the 1.2 mile long segment that extends from the Wise powerhouse at RM 27.6 to Placer County Water Agency’s (PCWA) Auburn Tunnel inflow at RM 26.4 as the “upper section” of Auburn Ravine. The 26.4 miles section that extends from the Auburn Tunnel to South Sutter Water District’s East Side Canal at RM 0 was designated as the “lower section”.
While there are currently no minimum instream flow requirements for Auburn Ravine in PG&E’s existing Federal Energy Regulatory (FERC ) license, Auburn Ravine is used by NID, PCWA, PG&E as a conduit to convey about 80 cfs (and at times up to 180 cfs) between April and October for consumptive water deliveries.
Additionally, between November and April, PG&E intermittently releases up to 80 cfs into Auburn Ravine from the South Canal due to a mismatch in capacities between the upstream powerhouses and the canal (Drum-Spaulding FLA).
For this study, the upper 11 miles of the 26.4 mile “lower section” was divided into 3 segments based on existing water diversion structures.
Reach 1 (The Cataract Reach) is an approximately 2.5 mile segment of Auburn Ravine from the Cataract at RM 26.5 to the Goldhill/AR 1 Diversion Dam at RM 24.
Reach 2 (Goldhill Reach) is an approximately 6.4 mile section from the Goldhill/AR 1 Diversion Dam at RM 24 to Hemphill Diversion Dam at RM 17.6.
Reach 3 (Hemphill Reach) is an approximately 2.1 mile section from Hemphill Diversion Dam at RM 17.6 to McBean Park at RM 15.5. A global positioning system (GPS) waypoint was taken at the downstream boundary of each habitat type. Flows averaged 18.95 cubic feet per second over the length of the survey. This study focused on the 6.4 mile reach between Goldhill Dam and Hemphill Dam (Reach 2), and the 2.1 mile reach between Hemphill Dam and McBean Park in the City of Lincoln (Reach 3). These were the reaches where staff observed FRCS (Fall Run Chinook Salmon) (Fall Run Chinook Salmon) during their 2012