Humboldt Bay is the only major harbor between San Francisco, CA, and
Portland, OR, and remains the only safe harbor of refuge for more than
200 miles1 either north or south along the coast. However, safe navigation
through the entrance is compromised by an offshore bar and intense wave
climate. Twin jetties stabilize the entrance, and channel depths are maintained by
frequent dredging. During winter storms this entrance is particularly dangerous.
Wave shoaling and strong currents in the entrance channel can be hazardous for
inexperienced vessel operators even in good weather.
Improvements to the interior harbor channels were begun in 1881, and the
first serious attempts at stabilizing the entrance were started in 1889. The high
energy and dynamic behavior of the entrance resulted in many attempts to
construct jetties, and substantial maintenance requirements of both the structures
and the entrance channels have been required over the years. The system of
interior channels also requires maintenance dredging, but predominantly at those
reaches that are influenced by the entrance conditions.
Humboldt Bay consists of three distinct basins, as shown in Figure 1.
Entrance Bay is directly east of the entrance channel and experiences waves that
propagate through the entrance. Entrance Bay has been and remains a dynamic
feature with active or recent erosion, channel filling, and spit building. Much of
the shoreline of Entrance Bay has been armored. South Bay is located directly
south of Entrance Bay and connected more by a constriction between the two
features than a defined channel. North Bay (also referred to as Arcata Bay) is
connected to Entrance Bay by a long relatively narrow maintained channel, the
North Bay Channel. The North Bay Channel bifurcates into two maintained
smaller channels, the Samoa Channel to the west and the Eureka Channel outer
reach and inner reach to the east. Humboldt Bay has a small watershed, and the
lack of significant riverine input minimizes the sediment load to the interior
portions of the bay, except in a few localized depositional areas. For example, at
the mouth of Freshwater Creek, localized deposition occurs but much of the
sediment load is carried into the Eureka Channel and North Bay Channel.
The approach to the data review was to focus on the data sources within
Humboldt County. This approach recognizes that most, if not all, of the historic
information available from the U.S. Army Engineer District, San Francisco, is
duplicated in the database collection of the Natural Resources Division,
Humboldt County Department of Public Works (DPW) and the San Francisco
District's Eureka Field Office. Experience has also indicated that most of the
historic literature concerning Humboldt Bay from various universities
A table for converting non-SI units to SI units of measurement is given on page vii.
Chapter 1 Introduction