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CITY OF LOS ANGELES CONSERVATION ELEMENT
Adopted September 2001
II-37
settles in the canyon, impairing the spectacular views tourists travel
thousands of miles to see.
The Navajo Generating Station, owned by the Salt River Project
consortium, which includes the DWP, was identified as one source of the
haze. It is located near Page, Arizona, south and east of the Glen
Canyon National Park and at the northeast edge of Grand Canyon National
Park, 80 miles from the main Grand Canyon visitor center. This coal
fired facility was constructed in 1975, before sulfur dioxide scrubbers
became available.
A series of studies were conducted (1987-89) to identify the sources of
Grand Canyon haze. Chemical tracers used in a National Park Service
study, partially funded by the consortium, identified some of the haze
as originating from the Navajo plant. Based on the study, the
Environmental Defense Fund sued the EPA for failing to enforce the
visibility provision of the Clean Air Act. An EPA study concluded that
in the winter, between November and March, haze reduced visibility at
the Grand Canyon from 150 miles to under 10 miles and that the Navajo
plant was a significant source. A verification study by the National
Academy of Sciences found that the winter haze was caused primarily by
automotive vehicle exhausts, that the Navajo plant "contributed
significantly" and that ore smelters, pollution from near and distant
urban areas (including Mexico) and other sources also contributed.
Based on the study, the EPA (1989) contended that the Navajo plant
contributed 40% of the introduced haze. It issued an order requiring
the consortium to install scrubbers.
The consortium agreed (1991) to reduce visibility impacts by installing
scrubbers designed to remove 90% of the sulfur dioxide emissions. These
were in service by August 1999. The historic agreement marked the first
time the EPA had enforced the Clean Air Act provisions requiring
protection of visibility at national parks and wilderness areas. For
the first time it acted solely to protect visibility and aesthetic
values, not health quality. The scrubbers may improve visibility at the
Grand Canyon by 7% on an average winter day. They are not expected to
improve visibility during summer months when air pollution from the Los
Angeles basin is the principal source of Colorado Plateau haze.
Another potential source of sulfur dioxide pollution affecting the
Colorado Plateau region is the Mohave Generating Station in Laughlin,
Nevada. The station is operated by the Southern California Edison
Company and is partially owned by the DWP. It was constructed in 1971
and has partial emission controls. As a result of negotiations, which
were concluded in 1999 to settle pending litigation, an agreement was
reached requiring the station to install additional emission controls
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CITY OF LOS ANGELES CONSERVATION ELEMENT
Adopted September 2001
II-38
by 2005, or to cease
operation in its present form, e.g., coal fired
facility.
Owens Lake and Owens Valley. City of Los Angeles and federal ownership
of almost all the lands in the Owens Valley, including mountain slopes
on both sides of the valley, has kept the area free from commercial
development, providing an almost unbroken view from Highway 395 of the
magnificent Sierra Nevada and White Mountains. Public ownership also
has enabled public access for hiking, hunting, fishing and winter
sports. But the city's diversion of the Owens River waters before they
reach Owens Lake and tapping of underground valley water have
contributed to impaired air quality and other impacts on the valley.
Owens Lake. The air quality issue associated with the drying of the
lake, primarily due to water diversion, resulted in dust mitigation
measures. These, in turn, resulted in side benefits to habitat and
wildlife enhancement. The majority of Owens Lake (95%) is owned by the
State of California and is under the authority of the State Lands
Commission.
The lake is a remnant of a large prehistoric freshwater lake which at
one time extended some 60 miles up and down Owens Valley, reaching a
depth of 320 feet. By the time settlers entered the valley in the mid-
19th century, Owens Lake had shrunk to a fraction of that size, to a
shallow, salty desert sink. Dissolved minerals and salts, which had
flowed into the lake for millennia, had become so concentrated by
evaporation that only algae, brine shrimp, brine flies and other
primitive life could survive.
By 1905, diversion of Owens River water by local farmers and an
extended drought shrank the lake even more. Shrinkage was accelerated
by the Los Angeles River Aqueduct. Completed in 1913, the aqueduct
diverted most of the remaining river water before it reached the lake.
By the late 1920s, the lake had become a dry lake, one of the largest
dry lakes in California. Its rapid shrinking had left shallow brine
pools within the dry lake bed and springs and seeps around its edges.
These wetlands supported remnants of the primitive marine ecosystem,
some of which remain to this day.
Due to the accelerated drying of the lake caused by the aqueduct
diversion, an alkaline crust of dissolved and crystallized minerals and
salts was created over much of the lake bed. Winds and shifting sands
lacerated the crust, resulting in dust becoming airborne during windy
periods.