Innovative Roadless Design
The Sweetheart Lake site is located in a federally designated Roadless Area. Since the 2001 Roadless Rule went into effect, the Forest Service has prohibited road construction in federally designated “roadless” areas. This rule has affected development in the Tongass National Forest.
A tunnel is an innovative road alternative. Hydropower projects require access to their site in order to move material, equipment and labor to build the development. This “access” typically requires many miles of “switchback road” to gain access to the dam site. In fact, all previous governmental studies of the Sweetheart Lake Hydroelectric resource determined that a multi-mile switchback road was required. Building this road would have meant the creation of an unattractive and treacherous road that would have contributed to serious erosion and water quality issues traversing sensitive habitat and wetlands. Collaboratively, our managers, environmental scientists, and engineers came up with an innovative way to get the access we needed without building a lake access road with habitat and scenery degradation. The power requirements of the resource require a 9 ft. X 9 ft. diameter tunnel to convey water from the lake to the powerhouse. By building a larger tunnel (15 ft. X 15 ft. horseshoe design tunnel) and creating a “side tap” to the lake we are able to move material and equipment to the lake, build the necessary infrastructure and then remove all the equipment, leaving a pristine environment with “no” road.
In this manner, we have eliminated a requirement to place a road in a designated roadless area while simultaneously preserving the scenic integrity of Gilbert Bay. Subsequent to our design and publishing our process, our tunnel methodology to avoid the use of a road has been copied in other hydropower applications.
Giving Sockeyes a Lift
Juneau is blessed to have a popular personal use sockeye fishery that is supported by the Douglas Island Pink and Chum (DIPAC) hatchery. Since the advent of this stocking program that was initiated in 1988, this “no deposit-no return” stocked fishery has supplied many Juneau households access to sockeye salmon that can be dip netted or cast netted.
This fishery is supplied sockeye salmon from DIPAC operations. Approximately 500,000 sockeye fry are placed in Sweetheart Lake. These fry overwinter in the lake and then outmigrate as smolt the following spring. These outmigrating smolts suffer from the treacherous bypass reach that is littered by many cascading falls and rocks that injure outmigrating sockeye smolt. In any given year, and depending on water levels and velocity, outmigrating smolts suffer anywhere from 50% to 80% mortality.
Juneau Hydropower and DIPAC is implementing a sockeye collection and outmigration system that has been collaboratively developed with the DIPAC hatchery to collect, capture and then transport the outmigrating sockeye to a smolt re-entry pool located adjacent to the powerhouse and then released through the tailrace near the existing barrier falls. This system is intended to reduce the mortality of outmigrating sockeye smolt and could lead to increases in returning salmon.
Our investment and annual operations of our Juneau Hydropower/DIPAC salmon collection and outmigration system and effort is considerably more than what would normally be required, but we chose to do so in keeping with our philosophy to enhance the environment and uphold Juneau’s community values of providing a robust personal use sockeye fishery.