Final Environmental Assessment for Mud Mountain Dam Upstream Fish Passage, Pierce County, Washington Prepared by: U.S. Army Corps of Engineers Seattle District Seattle, Washington May 2015 Page left intentionally blank Final Environmental Assessment — May 2015 Mud Mountain Dam Upstream Fish Passage Executive Summary This document is an environmental assessment (EA) prepared by the Seattle District, U.S. Army Corps of Engineers (Corps) for construction and operation of Mud Mountain Dam Fish Passage Facilities on the White River near Buckley, Washington. The current facilities located at river mile (RM) 24.3 will be replaced with a new fish barrier structure at the same location and a fish trap-and-haul facility on the opposite bank from the existing fish trap. This EA is intended to satisfy public involvement and disclosure requirements under the National Environmental Policy Act of 1969 (NEPA). The document describes the project and likely effects on terrestrial resources, aquatic resources, federally listed species under the Endangered Species Act (ESA) and effects on the human environment arising from the construction and operation of the proposed project. This document serves as the basis for the preparation of a Finding of No Significant Impact (FONSI). The existing White River barrier structure is located at RM 24.3 on the White River, which is a tributary to the Puyallup River 10.4 miles above the Puyallup’s mouth at Puget Sound. The White River is a large, powerful stream fed in its headwaters by glaciers on Mount Rainier. The river’s name derives from its characteristically high turbidity, which gives its waters a milky color, and the river transports a great deal of sediment, especially at high flows. The existing barrier structure was constructed in 1912 to provide for water diversion to operate the Puget Sound Energy (PSE) White River Hydropower Project (WRHP). The Corps entered into an agreement with Puget Sound Energy in 1941 to construct a temporary fish trap and haul facility co-located at the then named White River Diversion Dam. With approval of the Chief of Engineers, on 2 February 1948, USACE utilized the authorization provided by the 1936 Flood Control Act to enter into an agreement to acquire an easement from PSE for use of the Buckley site as a permanent fish trap location. PSE subsequently transferred ownership of the facilities to Cascade Water Alliance (CWA), a municipal and industrial (M&I) water supply consortium of local cities and water utilities which took over ownership of the existing barrier structure and all related PSE facilities, including water rights, on December 18, 2009. The Corps and CWA executed an operating agreement in 2010 to continue on-going maintenance of the barrier structure for the purposes fish trap-and-haul operations. Summary of Impacts Environmental impacts from the proposed project include both short-term and long-term changes to the baseline condition. Short-term impacts are episodic and principally associated with construction of the replacement fish passage structure. They may include increased turbidity, and temporary and permanent wetland and riparian losses due to staging and associated construction of facilities. During construction there is also a potential for stress or injury to fish associated with altered flow patterns or encounters with temporary rock structures or other cofferdam types. Some temporary impediment of upstream and downstream migration of fish might occur since construction of the proposed project will occur over several years, with some work needing to be done outside of the established fish construction window. Despite appropriate containment and control measures (best management practices), there is always a remnant potential for leaks or spills of chemicals including fuels, lubricants, concrete materials, adhesives, and other chemicals. A bald eagle nest is located nearby the proposed project and will be monitored to assess potential Final Environmental Assessment — May 2015 i Mud Mountain Dam Upstream Fish Passage impacts due to construction and operation. During construction, the existing adult fish collection facility will remain operational; however, it is possible that trap efficiency may be temporarily reduced due to changing flow characteristics, nearby noise or other construction related activities. The project produces long term benefits. The new fish passage structure will collect and pass significantly more fish, it will provide better attraction flows to the right bank and better reliability, as well as better ability to pass sediment and other material through the new barrier structure. More fish will be able to access upstream spawning areas, potentially increasing salmonid populations in the watershed. Additionally there will be reduced potential for stranding of juveniles due to flow manipulation caused by the dam repairs. Alternatives Considered For the MMD fish passage facility, the right or left bank locations were evaluated by the H&H/Fish Biologist Working Group which determined that, strictly from the standpoint of fish attraction and minimizing the risk of not meeting the 95 percent attraction criteria, an entrance on the left bank was preferable to a right bank location. However, this group also noted that an entrance on the right bank could also meet the 95 percent attraction criteria. The right bank was also expected to have enough available area to collect, load and transport 60,000 fish in one day. The group concluded that additional information was needed to determine if there was enough available area for processing fish on the left bank. Given this uncertainty the decision was made to proceed with a design for the fish trap facility on the right bank. Final Environmental Assessment — May 2015 ii Mud Mountain Dam Upstream Fish Passage TABLE OF CONTENTS 1 INTRODUCTION ........................................................................................................ 1 1.1 Authority ............................................................................................................. 1 1.2 Project Location ................................................................................................. 1 1.3 Background ........................................................................................................ 2 2 ALTERNATIVES ...................................................................................................... 21 2.1 Alternate Fish Trap Facility Locations .............................................................. 21 2.2 Alternatives Development at the Buckley Site.................................................. 23 2.3 Fishway Location (Left bank vs. Right bank).................................................... 24 2.4 Design Features ............................................................................................... 25 2.5 Design Considerations ..................................................................................... 36 2.6 Alternatives Considered at the Buckley Site but Eliminated from Detailed Evaluation and Selection of the Preferred Alternative. ....................... 42 3 PROPOSED PLAN .................................................................................................. 42 3.1 Project Description ........................................................................................... 42 3.2 Construction Considerations, Barrier Structure ................................................ 51 3.3 Muckleshoot Indian Tribe Fish Hatchery Accommodations, Issues, and Concerns ...................................................................................... 54 3.4 Cascade Water Alliance Accommodations, Issues, and Concerns .................. 56 3.5 Operation and Maintenance ............................................................................. 58 3.6 Annual Requirements ...................................................................................... 58 4 AFFECTED ENVIRONMENT ................................................................................... 61 4.1 Geology............................................................................................................ 61 4.2 Water Quality ................................................................................................... 62 4.3 Hydraulics and Hydrology ................................................................................ 67 4.4 Vegetation ........................................................................................................ 70 4.5 Wetlands .......................................................................................................... 71 4.6 Aquatic Resources ........................................................................................... 71 4.7 Terrestrial Resources ....................................................................................... 81 4.8 Cultural Resources .......................................................................................... 82 4.9 Federally Listed Endangered and Threatened Species ................................... 84 4.10 Climate and Air Quality .................................................................................... 88 4.11 Noise and Traffic .............................................................................................. 89 4.12 Hazardous and Toxic Wastes .......................................................................... 90 5 ENVIRONMENTAL EFFECTS OF THE PROPOSED PROJECT ...........................