2023-10357. Seattle City Light; Notice of Application Tendered for Filing With the Commission and Establishing Procedural Schedule for Licensing and Deadline for Submission of Final Amendments

Take notice that the following hydroelectric application has been filed with the Commission and is available for public inspection.

a. Type of Application: New Major License.

b. Project No.: 553–244.

c. Date Filed: April 28, 2023.

d. Applicant: Seattle City Light (City Light).

e. Name of Project: Skagit River Hydroelectric Project (project)

f. Location: The existing project is located on the Skagit River, in Whatcom, Snohomish, and Skagit Counties, Washington. The project occupies Federal lands under the jurisdiction of the National Park Service and the U.S. Forest Service.

g. Filed Pursuant to: Federal Power Act, 16 U.S.C. 791 (a)–825(r).

h. Applicant Contact: Chris Townsend, Director of Natural Resources and Hydropower Licensing, Seattle City Light, P.O. Box 34023, Seattle, WA 98124; telephone [phone].

i. FERC Contact: Matt Cutlip, (503) 552–2762 or [e-mail].

j. This application is not ready for environmental analysis at this time.

k. The Project Description: The project consists of three hydroelectric developments ( i.e., Ross, Diablo, and Gorge), a transmission line corridor that is about 100 miles long containing multiple transmission lines, two company towns ( i.e., Newhalem and Diablo), and numerous recreation and interpretive facilities. The project also includes 10,803.4 acres of fish and wildlife mitigation land.

The Ross Development is located at river mile (RM) 105.1 on the Skagit River and consists of: (1) a 540-foot-high, 1,300-foot-long concrete arch and gravity dam with two spillways, each of which has six 20-foot-high, 19.5-foot-wide radial tainter gates, two butterfly valves at an elevation of 1,346.2 feet, and two jet valves at elevations of 1,275.2 and 1,260.2 feet; (2) the 11,725-surface-acre Ross Lake with a storage capacity of 1,432,000 acre-feet at normal maximum water surface elevation of 1,608.76 feet; (3) two bifurcated intake structures with four 20-foot-wide, 198.13-foot-long openings and trashracks; (4) one 1,800-foot-long and one 1,634-foot-long, 24.5-foot-diameter concrete-lined power tunnels; (5) four 16-foot-diameter, 350-foot-long penstocks; (6) a powerhouse containing four generating units with a total authorized installed capacity of 352.5 MW; (7) two 230-kilovolt (kV), 3.8-mile-long transmission lines extending from the power plant to Diablo Switchyard; and (8) appurtenant facilities.

The Diablo Development is located at RM 101.2 on the Skagit River and consists of: (1) a 389-foot-high, 1,180-foot-long concrete arch and gravity dam, with a northern spillway that has 12 19-foot-tall, 20-foot-wide radial tainter gates and a southern spillway with seven 19-foot-high, 20-foot-wide radial tainter gates, and a valve house containing three butterfly valves and one Larner Johnson type valve at an elevation of 1,050.6 feet; (2) the 905-surface-acre Diablo Lake with a gross storage capacity of 88,880 acre-feet at normal maximum water surface elevation of 1,211 feet; (3) two bifurcated intake structures with four approximately 16.75- to 18.75-foot-wide, 153.71-foot-long openings and trashracks; (4) a 19.5-foot-diameter, 1,990-foot-long power tunnel, of which 1,800 feet is concrete-lined and the other 190 feet is steel-lined; (5) two 15-foot-diameter penstocks and two 5-foot-diameter penstocks each 290 feet long; (6) a surge tank; (7) a powerhouse containing four generating units with a total authorized installed capacity of 158.47 MW; (8) a switchyard; (9) a 230-kV, 5.8-mile-long transmission line extending from Diablo Switchyard to the Gorge Switchyard; (10) three 230-kV, 87.6-mile-long transmission lines running from Diablo Switchyard to Bothell Substation; and (11) appurtenant facilities.

The Gorge Development is located at RM 96.6 on the Skagit River and consists of: (1) a 300-foot-high, 670-foot-long combination concrete arch and gravity dam with a 94-foot-wide spillway that has two 50-foot-high, 47- foot-wide fixed wheel gates and a log chute; (2) the 235-surface-acre Gorge Lake with a gross storage capacity of 8,200 acre-feet at normal maximum water surface elevation of 881.5 feet; (3) a bifurcated intake structure with two 20-foot-wide, 88.9-foot-long openings and trashracks; (4) a 20.5-foot-diameter, 11,000-foot-long concrete-lined power tunnel; (5) three 10-foot-diameter penstocks and one 15-foot-diameter penstock, each 1,600 feet long and each fitted with a 10-foot-diameter butterfly biplane and relief valves; (6) a surge tank; (7) a powerhouse containing four generating units with a total authorized installed capacity of 189.3 MW; (8) a switchyard; (9) a 230-kV, 36.8-mile-long transmission line extending from Gorge Switchyard to North Mountain Substation; and (10) appurtenant facilities.

The three project developments are hydraulically coordinated to operate as a single project. Project operation under the existing license is designed to meet four objectives, which are prioritized as follows: (1) flood control, (2) salmon and steelhead protection flows downstream of Gorge Powerhouse, (3) recreation, and (4) power generation. To achieve these goals, City Light adheres to specific license requirements for Ross Lake levels and for stream flows and ramping rates downstream of Gorge Powerhouse.

Under existing operations, Ross Lake is drawn down on a yearly basis during winter to capture flows from spring runoff and to provide for downstream flood control. The drawdown typically begins after Labor Day and continues until the lake reaches its lowest level in late March or early April. The current license requires City Light to draw down Ross Lake to a level that provides 60,000 acre-feet of storage for flood control by November 15 and 120,000 acre-feet by December 1 and to maintain this available storage through March 15. Ross Lake levels are also managed to meet recreational needs during the summer months. The current license requires City Light to fill Ross Lake as soon as possible after April 15, achieve full pool depth by July 31, and maintain full pool depth through Labor Day.

The Diablo Development is operated to regulate flow between the Ross and Gorge Developments. Under normal operation, Diablo Lake typically fluctuates between 4 and 5 feet per day.

The Ross Powerhouse and Diablo Powerhouse are typically operated continuously to pass flow downstream, although generation is occasionally increased or decreased for short periods to help meet load-following demand or other project purposes.

The Gorge Development is operated primarily to provide a continuous, stable flow regime in the upper Skagit River for salmon and steelhead protection. City Light typically limits Gorge Lake fluctuations to about 3 to 5 feet and does not typically operate the powerhouse to meet load-following demand. The Gorge Development creates a 2.5-mile-long bypassed reach of the Skagit River between the dam and powerhouse. There are no minimum flow requirements in the existing license for the Gorge bypassed reach. Therefore, except during spill events at Gorge Dam, bypassed reach flow is limited to accretion flow, spill-gate seepage, tributary input, and precipitation runoff.

l. In addition to publishing the full text of this notice in the Federal Register , the Commission provides all interested persons an opportunity to view and/or print the contents of this notice, as well as other documents in the proceeding ( e.g., license application) via the internet through the Commission's Home Page ( http://www.ferc.gov) using the “eLibrary” link. Enter the docket number excluding the last three digits in the docket number field to access the document (P–553). For assistance, contact FERC at [e-mail], (866) 208–3676 (toll free), or (202) 502–8659 (TTY). At this time, the Commission has suspended access to the Commission's Public Reference Room. For assistance, contact FERC at [e-mail] or call toll free, (886) 208–3676 or TTY (202) 502–8659.

m. You may also register online at https://ferconline.ferc.gov/​FERCOnline.aspx to be notified via email of new filings and issuances related to this or other pending projects. For assistance, contact FERC Online Support.

n. Procedural Schedule:

The application will be processed according to the following preliminary Hydro Licensing Schedule. Revisions to the schedule may be made as appropriate.

Milestone	Target Date
City Light files final study report for Study CR–04 Properties with Traditional Cultural Significance Study 1	March 2024.
Notice of Acceptance/Notice of Ready for Environmental Analysis	April 2024.
Filing of recommendations, preliminary terms and conditions, and fishway prescriptions	June 2024.
1 City Light indicates in section 4.2.9.1 of the Final License Application Exhibit E that the study results for this Commission staff-approved study would be filed in the first quarter of 2024.

o. Final amendments to the application must be filed with the Commission no later than 30 days from the issuance date of the notice of ready for environmental analysis.

Dated: May 9, 2023.

Kimberly D. Bose,

Secretary.