Hood Canal

Hood Canal is a fjord forming the western lobe, and one of the four main basins,Features Of Puget Sound Region: Oceanography And Physical Processes
Chapter 3 of th

King County Department of Natural Resources, Seattle, Washington, 2001. of Puget Sound in the US state of Washington. It is one of the minor bodies of water that constitute the Salish Sea. Hood Canal is not a canal in the sense of being a man-made waterway—it is a natural waterway.

Geography

Hood Canal is long and narrow with an average width of and a mean depth of . It has of shoreline and of tideland. Its surface area is and it contains a volume of water totaling . Hood Canal extends for about southwest from the entrance between Foulweather Bluff and Tala Point to Union, where it turns sharply to the northeast, a stretch called The Great Bend. It continues for about to Belfair, where it ends in a shallow tideland called .

Along its entire length, Hood Canal separates the Kitsap Peninsula from the Olympic Peninsula of Washington. The U.S. Navy's Naval Base Kitsap, Bangor Annex, is located on the eastern shore of Hood Canal near the town of Silverdale. Hood Canal has several internal bays, the largest of which is . Most of Dabob Bay is a Naval Restricted Area, and is used by the submarines stationed at the Bangor Base. Quilcene Bay is an inlet extending northwest from Dabob Bay. Near the north end of Hood Canal is Port Gamble, a bay and a town of the same name.

Several rivers flow into Hood Canal, mostly from the Olympic Peninsula, including the Skokomish River, Hamma Hamma River, Duckabush River, Dosewallips River, and Big Quilcene River. Small rivers emptying into Hood Canal from the Kitsap Peninsula include the Union River, Tahuya River, and Dewatto River.

Geology

Hood Canal and the rest of Puget Sound were created about 13,000 years ago, during the Late Pleistocene, by the Puget Lobe of the Cordilleran Ice Sheet.

History

Hood Canal was named by the Royal Navy Captain George Vancouver on May 13, 1792, in honor of Admiral Lord Samuel Hood of that navy. Vancouver used the name "Hood's Channel" in his journal, but wrote "Hood's Canal" on his charts. The United States Board on Geographic Names decided on "Hood Canal" as its official name in 1932.

Roads and bridges

U.S. Route 101 runs along the west shore of Hood Canal, south of Quilcene.

Hood Canal is spanned by the Hood Canal Bridge, the third longest floating bridge in the world at . According to the Washington State Department of Transportation, the Hood Canal Bridge is the only floating bridge in the United States constructed on saltwater, although there are others, such as Nordhordland Bridge and Bergsøysund Bridge in Norway. The Hood Canal Bridge accommodates sixteen and a half foot tides.

Recreation

State parks on the shores of Hood Canal including Belfair, Twanoh, Potlatch, Triton Cove, Scenic Beach, Dosewallips, and Kitsap Memorial. Prominent shoreside activities include swimming, boating, fishing and shellfish gathering.

Theler Wetlands is located at the tip of the Canal in Belfair. It provides a few miles of trails and a protected environment for marsh and estuary birds and plants.

There are many small towns located along the length of the Hood Canal, mostly on the western shore. The latter are near hiking and recreation within the Olympic National Forest and the Olympic National Park. Some of the more popular areas include Staircase Campground and Hama Hama Recreation Area and act as the gateways to miles of hiking trails through quiet, lush forests.

Low oxygen levels

September 2006 marked the discovery of the largest dead zone in the history of Hood Canal. The dead zone may have been caused by low oxygen levels due to algal blooms. Algal blooms occur in part because of warm weather and the slow turnover of water in the southern end of the canal, causing the build-up of nutrients from fertilizers and leaky septic systems. Organic matter, brought in by ocean water and certain trees, could additionally be contributing to the high nitrogen levels in the basin. Excess nutrients and organic matter causes a body of water to lose oxygen, through a process called eutrophication. In Hood Canal, eutrophication has led to unwanted algae blooms. Nitrogen combined with sunlight triggers algal growth. A lack of sufficient consumers has resulted in a mass overgrowth of algae in the basin. When the algae die, bacteria feed and their populations explode, robbing the water of oxygen. A state of hypoxia is created.

The fish kill may also be part of a natural 50-year cycle of oxygen levels in the canal, which has merely been influenced (but not controlled) by anthropogenic activity. Natural causes of hypoxia in Hood Canal include the timing of freshwater inflows, water layer stratification resulting from seasonal changes in surface temperature, and climate change. The oxygen level may also be partially due to a change in wind direction. The prevailing north wind generally pushes oxygenated water into the oxygen-depleted area. A sustained south wind will cut off this source of oxygen. Coastal upwelling from the Strait of Juan de Fuca bring in a surplus of nutrients into the Puget Sound, but fail to circulate oxygen through Hood Canal. Chronic hypoxia is observed year-round. This area of low-oxygen is often seen in Lynch Cove, but has been spreading towards the mouth of Hood Canal.

In May 2006, divers searching for invasive species discovered a mat of marine bacteria covering a stretch where all normal sea life was dead. The mat dissipated five months later.Dodge, John
"Bacterial mass in canal dissipates"
''The Olympian''; October 26, 2006 Jan Newton, oceanographer at the University of Washington, said it was important to note that Hood Canal has had very low oxygen for a long time. Similar mats have been found near Tacoma, Washington; San Diego, California; New York City; and New Orleans, Louisiana. Hypoxia and its detrimental effects on fish have been documented in Hood Canal since the 1970s. But hypoxia's impacts on the area's wildlife have been more significantly linked to growing urbanization along the coast. A recent study determined DO content, oxygen saturation, of the Sound's Main Basin to consistently stay around 5 mg/L from the 1950s up through 2005. DO concentration in Hood Canal, however, was identified to have dramatically decreased from 5–6 mg/L in the 1950s to less than 0.2 mg/L in the twenty-first century. As of 2000, the National Research Council defined hypoxia to occur at a DO level of <2 mg/L—making Hood Canal's current 0.2 mg/L composition far below life-sustaining conditions.

Hood Canal's hypoxic state has had devastating effects on the sub-basin's biodiversity. Valuable commercial species such as geoduck clam and Dungeness crab may be adversely affected by hypoxic conditions. Critically low oxygen levels, due to increased bacterial growth, were observed in the lower portion of Hood Canal during the summer months of 2004 and 2005. A low dissolved oxygen content in Anna's Bay and Lynch Cove is believed to have been responsible for the corresponding decline in spot shrimp catch by Skokomish Nation fishers within the same period of time. In 2010, there was a massive fish kill in the southern part of Hood Canal. Hundreds of fish and thousands of shrimp were found washed up onto the shore. Jan Newton, a local oceanographer, concluded that the water contained less than 1 milliliter per liter of dissolved oxygen and that such a low level is extremely stressful, often lethal, to the marine life in Hood Canal. The effects of Hood Canal's hypoxic conditions are clearly seen by the public through massive fish kills, but it is important to identify other harmful impacts resulting from a lack of oxygen in the basin. Eelgrass