In order to identify the potential natural and anthropogenic factors that may be contributing to Hood Canal’s severely depleted oxygen levels, the Hood Canal Dissolved Oxygen Program (HCDOP) must take a watershed approach. Hood Canal’s watershed is much larger than the canal itself; the watershed’s borders roughly coincide with the Olympic Mountains to the west, Shelton to the south, the Bremerton Airport to the east, and the Hood Canal Bridge to the north.
Almost all precipitation falling within these boundaries eventually flows into one of the streams that discharge into Hood Canal. Anthropogenic nutrient loading and/or land use modifications within Hood Canal’s watershed may contribute to the increased degradation of water quality in Hood Canal by increasing nutrient fluxes into the canal. Increased nutrient fluxes, especially of nitrogen, can cause excessive algal biomass production in marine systems. Algal decomposition, in turn, causes severe depletion of dissolved oxygen in these systems. The HCDOP currently employs three interrelated strategies in its effort to identify potential terrestrial contributions to the canal’s low dissolved oxygen levels:
