About Sweetheart Lake
Strengthening Juneau’s power grid with renewable energy
Sweetheart Lake is located within the territorial limits of the City and Borough of Juneau approximately 33 miles south of downtown Juneau on the east shore of Gilbert Bay. Sweetheart Lake drains into Gilbert Bay (an arm of Port Snettisham) via Sweetheart Creek. The Sweetheart Lake Hydroelectric Facility is designed to have an installed electrical capacity of 19.8 megawatts (MW) and the facility will generate an average of 116,000 megawatt-hours (MWh) annually. This hydropower capacity will strengthen the grid backbone of Juneau from one end of the borough on the southern side to the northern end for grid reliability not only now, but for future generations.
It has been a long road to get ready for construction, but all of the major hurdles have been completed. JHI is now a certified public utility (link to news article) that will employ a large battery energy storage system and utilize 56 miles of transmission lines. Ameresco is the EPC contractor that will construct the facility. A few tiny items remain before construction of the facility which hopefully is slated to begin in 2026.
Simple, Gravity Driven, Renewable Energy Designed by Nature
For millennia, man has been harnessing the power of water as the world’s first sustainable energy source. Southeast Alaska has been called the “Saudi Arabia of Hydropower”. Our rainforest and weather pattern certainly lends support that we are blessed to live in the Tongass rainforest where we can work, play, live and support our families in a sustainable manner based on hydropower as our primary energy source.
The Sweetheart Lake Hydroelectric Facility is a state-of-the-art lake-tap design hydropower facility that converts the power of water gravity into electricity. Aside from the multiple innovations employed at the Sweetheart facility, the facility produces storage hydropower. That means that the facility provides Juneau when it needs it the most allowing the stored water to be drawn down as needed in concert with nature.
The result of this natural resiliency is that there is a constant and predictable supply of electricity to provide energy and warmth for Juneau’s economy and homes.
Why Hydropower like Sweetheart Lake is an important energy source
The Sweetheart Lake hydro project has wide support at the Federal and State levels.
- Executive Order 14154, “Unleashing American Energy,” signed January 20, 2025 View. It directs agencies to review and remove actions that burden domestic energy development and calls for attention to a range of resources, including hydropower.
- Executive Order 14153 – Unleashing Alaska’s Extraordinary Resource Potential, signed January 20, 2025 View. This order focuses on unlocking Alaska’s resource and energy development potential. It supports expedited development of energy projects in Alaska and demonstrates a favorable federal policy environment for infrastructure and energy permitting in the state.
- Alaska SB 179 View explicitly recognizes lake tap hydropower as a renewable energy resource in Alaska.
- Governor Dunleavy’s Administrative Orders 344 View / 345 View and Alaska Hydropower Day 2025 proclamation View is evidence of state-level executive support for hydropower development.
FAQ
What is the Juneau Hydropower Utility System?
The Juneau Hydropower Utility System is JHI’s integrated clean-energy utility system for Juneau, Alaska. The system includes hydropower generation, high-voltage transmission, battery energy storage, submarine cable, fiber optic communications, substations, and an entire 106 square mile certificated electric utility service territory separate from any other utility.
The system includes:
- The 19.8 MW Sweetheart Lake Hydroelectric Project
- Approximately 56 miles of high-voltage transmission infrastructure
- Utility interconnections with the Juneau grid
- Submarine power and fiber optic cable systems
- A planned 10 MW / 20 MWh Battery Energy Storage System (BESS)
The system is designed to provide long-term firm renewable energy, energy security, grid reliability, communications infrastructure, and economic growth for Juneau and Southeast Alaska.
Is JHI a regulated utility?
Yes. Juneau Hydropower, Inc. is a certificated electric public utility regulated by the Regulatory Commission of Alaska (RCA). JHI holds CPCN No. 768 for its approved utility service territory and has a legal obligation to serve current and future customers within that territory.
Is Juneau Hydropower locally owned and operated?
Yes. Juneau Hydropower is locally owned and intends to locally operate and maintain the utility system in Juneau for the long-term benefit of the community.
What are the main public benefits?
The Juneau Hydropower Utility System provides:
- Firm renewable hydropower
- Reduced diesel generation
- Improved grid reliability
- Battery-backed energy resilience
- Fish-friendly renewable energy
- New high-voltage transmission infrastructure
- Communications and fiber infrastructure
- Support for federal and Coast Guard operations
- Local and statewide economic growth
- National, state, and local energy security for future generations
How large is JHI’s service territory?
JHI’s utility system represents approximately 106 square miles of certificated electric utility service territory in the City and Borough of Juneau. The service territory is about five times larger than Manhattan.
What is the main generation project?
The primary generation project is the 19.8 MW Sweetheart Lake Hydroelectric Project located about 30 miles south of Juneau. It is clean, sustainable, fish-friendly hydropower designed to provide firm renewable energy to Juneau and Southeast Alaska.
Why is the Sweetheart Lake Project significant?
Sweetheart Lake is one of the most significant new traditional dam-storage hydropower projects advanced in Alaska and the United States in decades.
The project:
- Is the largest traditional dam-storage hydropower project of about 20 MW advanced in Alaska since 1994
- Represents one of the largest new traditional dam-storage hydropower projects of its size advanced in the United States since 1994
- Adds firm renewable storage power to Juneau’s isolated electric grid
- Creates long-term renewable energy and storage infrastructure for Alaska’s capital city
How much energy will the project produce?
Sweetheart Lake is expected to generate approximately 116,000 MWh per year, equal to about 116 million kilowatt-hours annually.
The project adds over 20% new renewable generation to Juneau’s electric system and strengthens long-term energy security for the region.
Does the project have permits and licenses?
Yes. The project has completed major federal environmental review and received its original FERC license.
Does the project have all required land tenure, easements, and rights-of-way?
Yes. The project has secured the required land tenure, easements, permits, utility corridor agreements, and rights-of-way necessary for the approved utility system, transmission corridors, interconnections, and submarine cable routes.
Has USDA/RUS accepted the federal environmental review?
Yes. USDA Rural Utilities Service adopted and relied upon the FERC Final Environmental Impact Statement for its environmental review. Addtionally, the USDA RUS has conducted an Environmental Assessment on the Northern Transmission line and BESS of the utility system and issued Finding of No Significant Impact (FONSI).
Is the hydroelectric facility fish-friendly?
Yes. The project is designed as fish-friendly hydropower and helps demonstrate how modern hydropower can harmonize with salmon protection, restoration, and long-term fishery support.
The licensed project includes:
- Fish screens
- Fish exclusion structures
- Minimum stream flows
- Pulse flows for fish movement
- Spawning habitat monitoring
- Potential gravel augmentation
- Sockeye smolt collection and transport systems
These measures are designed to protect and potentially increase Sweetheart Creek sockeye salmon returns.
Does JHI have authority to use and interconnect with the Juneau grid?
Yes. The RCA approved the required interconnection, transmission service, and transmission accommodation agreements necessary for JHI to interconnect with and use the Juneau transmission grid.
What grid agreements have been approved?
Approved agreements include:
- Mist Island interconnection agreement
- Lena Substation interconnection agreement
- Transmission and Ancillary Services Agreement
- Transmission Accommodation Agreement
What does the Mist Island Switchyard do?
The Mist Island Switchyard connects JHI’s Sweetheart Lake transmission system to the Snettisham transmission system.
This improves Juneau energy security by providing another firm renewable power source when avalanches, transmission failures, or other outages affect the existing Snettisham system.
What does the Lena Substation interconnection do?
It connects JHI’s 69 kV northern transmission system to AEL&P’s Lena Substation and the Juneau electric grid.
Does JHI have transmission service across the Juneau grid?
Yes. The RCA-approved Transmission and Ancillary Services Agreement provides JHI with long-term conditional firm transmission service between Mist Island and Lena Substation.
How much transmission infrastructure does the system add?
The utility system includes approximately 56 miles of high-voltage transmission infrastructure.
That represents approximately 3% of Alaska’s total high-voltage transmission system and adds long-term state and regional energy infrastructure for future generations.
Does the system include battery storage?
Yes. The system includes a planned 10 MW / 20 MWh Battery Energy Storage System designed to:
- Improve grid reliability
- Reduce outages
- Stabilize renewable generation
- Support emergency operations
- Provide backup power capability
- Strengthen energy security in the JHI service territory
Does the system include fiber optic communications?
Yes. The utility system includes submarine composite power and fiber optic cable infrastructure supporting:
- Utility operations
- Grid controls
- Communications systems
- Future broadband and telecommunications opportunities
Does the project support the U.S. Coast Guard?
Yes. The system supports Juneau, the U.S. Coast Guard Arctic Division headquarters, and expanding Coast Guard operations in Alaska.
JHI has identified the utility system as defense-supporting critical infrastructure important to Arctic readiness and national energy security.
How does the project support the USCGC Storis?
The USCGC Storis is expected to require approximately 4 MW of electricity from the Juneau grid.
JHI’s utility system adds firm renewable power, transmission capacity, and grid reliability needed to support that federal load.
Does the system create jobs in Juneau?
Yes. The system creates direct and indirect jobs including:
- Construction
- Utility operations
- Maintenance
- Marine work
- Engineering
- Communications infrastructure
- Long-term utility employment
The system also supports broader economic growth by helping stabilize and lower long-term energy costs.
Why is this utility good for Juneau?
The Juneau Hydropower Utility System strengthens Juneau’s electric grid, improves energy security, reduces diesel dependence, and supports long-term economic growth.
New generation and transmission infrastructure are required for Juneau’s 21st-century economy.
The system supports:
- Lower-cost electric heat
- Shore power
- Grid reliability
- Local renewable energy production
- Reduced exposure to foreign-controlled oil price volatility
- Local jobs and economic growth
- Mining and industrial development
- Communications infrastructure
- Emergency backup and resilience
- Long-term locally operated utility infrastructure
The project also creates a second major renewable power source for Juneau, improving reliability when outages affect the Snettisham system.
How does the project benefit the State of Alaska?
The utility system strengthens Alaska’s energy infrastructure, supports long-term economic growth, improves grid reliability, and adds major renewable generation and transmission capacity in Southeast Alaska.
State benefits include:
- Lower-cost and reliable energy
- Reduced diesel dependence
- Critical mineral and mining development
- Arctic and Coast Guard support infrastructure
- Long-term infrastructure investment
- Statewide job creation
- Expanded transmission and communications systems
- Energy security for Alaska’s capital city
How does the project benefit the United States?
The project supports national energy security, Arctic readiness, domestic energy production, grid resilience, and critical mineral development.
The project aligns with local, state, and federal public policy priorities by adding:
- Firm renewable hydropower
- High-voltage transmission
- Battery storage
- Grid resilience infrastructure
- Submarine cable systems
- Fiber optic communications infrastructure
The system also aligns with recent federal public policy, national energy directives, and Defense Production Act priorities supporting:
- Reliable domestic energy infrastructure
- National defense infrastructure
- Critical mineral supply chains
- Arctic operations
- U.S. Coast Guard readiness
- Domestic manufacturing and infrastructure investment
- Reduced dependence on foreign energy markets
Is there federal support for new generation and transmission developments like this?
Yes. Recent federal directives prioritize:
- Energy infrastructure
- Grid reliability
- Domestic energy production
- Alaska resource development
- National defense-supporting infrastructure
- Transmission expansion
- Critical minerals
- Arctic readiness
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