Assessment of Factors Limiting Salmon Production in Devil's Hole Creek

The Washington Department of Fish and Wildlife Wild Salmon Production Unit was contracted by the Navy in 1998 through 2000 (Navy contract #’s N6871198LT80043, and N6871199LT90019) to provide a species and habitat assessment and corrective design project for the Devil’s Hole watershed on the Naval Submarine Base, Bangor, Washington. The purpose of this project was to identify species use and determine factors negatively affecting salmon production in the Devil’s Hole watershed and to recommend corrective measures for these factors.

This is the final report for the project. It describes the methods and results of the species and habitat assessment work conducted during the spring through summer periods of 1999 and 2000. Elements evaluated included current fish use of the watershed, summer stream temperatures, spawning habitat quality, macroinvertebrate indicators, bank and riparian conditions, channel morphology, stream habitat condition, fish passage conditions, and the location/impact of point source discharges for all of the stream network accessible to anadromous salmonids as well as most of that used by resident salmonids. The report also describes factors we believe are most limiting to anadromous salmonids and provides recommendations for corrective measures to improve utilization and survival of salmonids in the Devil’s Hole watershed.

Site Description

The Bangor Naval Submarine Base is located adjacent to Hood Canal on the northern Kitsap Peninsula (Figure 1). The facility is 6,692-acres in size. The site was first purchased by the Navy in 1942. After serving as a U.S. Ammunition Depot for a number of years, the site was established as a submarine base in 1977. The base has grown substantially during the 1990's as a result of Base Closure and Realignment actions in 1991 and 1993.

The entire Devil’s Hole Creek watershed is within the Bangor Submarine Base complex (Figure 1). The mainstem Devil’s Hole Creek travels in a northerly direction before entering Hood Canal approximately 1/4-mile southwest of the Delta Pier. The watershed is located in township T26N, range R1E, sections 18, 19, 20, and 30; and township T26N, range R1W, sections 24 and 25. Total area of the watershed is 2.61 mi² (United States Geological Survey data).

A reservoir was created near the mouth of the stream in the 1940's when Sea Lion Road was constructed (Tom James pers. comm.). The reservoir, Bangor Lake or Devil’s Hole Lake, has a surface area of about 2.6-hectares (Wolcott 1961). A fishway was constructed at the lake outlet in 1979 to provide access to the watershed for anadromous salmonids (Tom James pers. comm.). Potentially fish-bearing stream channels in the watershed include the mainstem Devil’s Hole Creek and five un-named tributaries (Figure 2). Four of the tributaries are right-bank tributaries (i.e., enter Devil’s Hole Creek from the right-side of the stream when looking downstream) and one is a left-bank tributary. These have been arbitrarily named for identification purposes as RB1-4 and LB1. RB1 enters Bangor Lake, while the other tributaries enter Devil’s Hole Creek upstream of the reservoir.

The climate in the region has a strong maritime influence characterized by cool, dry summers and mild, wet winters. Precipitation averages 50 to 65-inches per year with over 98% falling in the form of rain (WDNR 1995). Only 5 to 10% of the annual precipitation occurs between July and September.

The watershed has been highly influenced by the advance and retreat of continental glaciers over the last two million years. Surficial sediments have been primarily influenced by the most-recent Fraser Glacier, which occurred from 15,000 to 13,500 years ago. Sedimentary deposits left by the glacier include unconsolidated outwash (comprised of sands and gravel), till, and lacustrine deposits (primarily comprised of silt and clay) (WDNR 1995). Of these, outwash deposits with a high composition of sand are particularly common in the Devil’s Hole watershed and have a substantial effect on channel morphology and fish habitat.