Big Bear Falls Assemssment-Lidar P1

Worksite #2: The Thermal Infrared Radar (TIR) flight was flown August 3-5, 2015 during the warmest part of the summer, to identify water temperature and quantity of pools available to juvenile steelhead rearing or lethal to juvenile steelhead. A total of 104 miles of streams were flown to identify critical rearing water in the Potlatch River Watershed. These streams included the following: Middle Potlatch, Big Bear (including Little Bear), lower Pine, Cedar, Boulder, and Little Boulder creeks and the mainstem Potlatch River from Cedar Creek to five miles beyond the confluence with Little Boulder Creek.

The LiDAR flight was completed in October of 2016. A total area of 22,000 acres was mapped in the same waters as the TIR flight.

Worksite #1: IDFG contracted HDR, Inc. (engineering consultants) for three conceptual design alternatives for improving passage around Big Bear Falls. The report provided design details for each alternatives and construction cost estimates associated with each. The IDFG staff also prepared a justification memorandum to accompany the conceptual designs. This project area encompasses approximately two miles.

Variations from the original project proposed: The TIR flight was added to the project and the LiDAR coverage could include portions of other Potlatch River subwatersheds in addition to the Big Bear Creek drainage. The corrected LiDAR coverage was not delivered to IDFG until the end of the project contract term and did not allow time for interpretive work to be completed. The proposed project intended to conduct a fish presence/absence survey on 15 stream miles. This was part of the project was modified to two transects (100 m each) that were surveyed below the Big Bear Falls and 8 transects (100 m each) surveyed above the falls (total of 0.62 miles). The balance of the Bonneville cash match identified for this project was used for the conceptual design alternatives contract work.

Evaluation of Big Bear Falls will provide an assessment and preliminary design alternatives for passage improvement into the upper two thirds of the watershed and assess the efficacy of proceeding with implementation. LiDAR is expected to greatly benefit future and current restoration identification and implementation by providing baseline data on habitat condition, barriers, stream, and floodplain condition. LiDAR will be used to evaluate restoration potential and to develop preliminary engineering designs including: longitudinal stream profile, cross sections, stream sinuosity, meadow function and other topographic features with a high degree of accuracy. Future cost savings in engineering and field crew costs are anticipated.

In total, this project will expand the potential for habitat restoration within the Big Bear drainage and provide good opportunity for a population level response of steelhead within the Potlatch River watershed.