3.3 Water Resources
WATER RESOURCES
3.3
Water resources analyzed in this study include physical processes and chemical properties. Physical
processes include tides and water levels, currents, wave exposure, and littoral processes. Chemical
properties are characterized by temperature, salinity, dissolved oxygen, and water visibility (turbidity).
The following is a discussion of the factors that contribute to the quality of existing water resources at the
proposed borrow sites and receiver beaches. Data is summarized from the previous Navy documentation
(1997a, 1997b) and the biological resources technical report which is provided as Appendix D (refer to
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Section 3.1.5 and Table 5 of that Appendix). The survey methods and literature/data review for water
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quality are described in Section 3.4.1.
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3.3.1
Physical Processes
The general oceanic circulation off the coast of California is dominated by the long-term mean southward
flow associated with the California Current. In southern California, the current divides into a southward
extension and a recirculating flow toward the coast. The recirculation forms a counterclockwise eddy that
is present most of the year. An inshore countercurrent (Davidson Current) moves north from Baja
California and is detected along the southern California coastline from October to April.
Currents move large amounts of water with varying levels of temperature, salinity, dissolved oxygen, and
nutrients in and out of the study area. These water masses vary in strength and are influenced by weather
patterns and seasonal variations. In addition, nearshore currents vary along the coast in response to
coastline orientation, bottom topography, and tides. Kelp forests may slow ocean currents to one-third of
the normal rate.
Waves (swell) also exert a significant influence upon the water column and nearshore bottom habitats. In
shallow water, the circular motion within the water column can induce the resuspension and transport of
bottom sediments. Wave height and high-velocity swell tend to be most prominent during winter and spring
due to storms from the North Pacific.
All of southern California has a mixed semidiurnal (daily) tide with two high tides and two low tides, each
of different magnitude, every 24 hours and 50 minutes. The range between mean high and low water is
approximately 3.7 feet and the diurnal range is approximately 5.4 feet.
Regional Beach Sand Project EIR/EA
Page 3.3-1
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