construct. Facing an urgent need for the changes, the MWD expedited the
design and construction so that project delivery required only 10 months.
Established in 1928, the MWD operates the 242 mi long Colorado
River Aqueduct (CRA), as well as five regional water treatment plants,
nine reservoirs, 16 hydroelectric plants, 830 mi of large-diameter pipelines and tunnels, and approximately 400 connections to member agencies. On average, the district delivers about 1. 7 billion gal of treated and
untreated water per day to the roughly 18 million people living within
its 5,200 sq mi service area.
In 2014 California received its second-lowest amount of snowfall in
the past 100 years, prompting the Department of Water Resources to
limit allocations to member agencies to only 10 percent of the requested allocation, a level low enough to set a record. Because the Mills plant
could receive water only from the SWP, the MWD was concerned that
the facility would not receive adequate supplies to meet demand. At
that time the Mills plant received raw water either by gravity from the
SWP’s Santa Ana Valley Pipeline (see the figure at the top of page 66)
or by pumping from Lake Perris, an SWP reservoir (see the figure at the
bottom of page 66).
Against this backdrop, the MWD decided to accelerate the planned connection between two of its key facilities, the Lakeview Pipeline and the Inland Feeder, which parallel each other and are separated by only a few hundred feet along a stretch of several miles. Located in Riverside County, the
11 ft diameter, 11. 5 mi long Lakeview Pipeline delivers SWP water from
Lake Perris to another MWD facility, the San Diego Canal. The Inland
Feeder is a 12 ft diameter, 50 mi long pipeline that begins at the Devil Canyon Power Plant Second After Bay, in San Bernardino, and delivers SWP
water to Diamond Valley Lake, in Riverside County. Owned by the MWD,
Diamond Valley Lake is the largest reservoir in Southern California. Linking the Lakeview Pipeline and the Inland Feeder would enable the MWD
to deliver water stored at the lake to the Mills plant, a distance of 22 mi.
The Lakeview Pipeline was constructed in 1972, and over the years
it has experienced significant problems, particularly related to its bell-and-spigot joints. In fact, 139 of the pipeline’s 1,520 joints have required
repairs to address leakage, necessitating the shutdown of the pipeline
on numerous occasions. In 2012 the MWD conducted an internal
Construction of the
portions of the connection that
were needed so that water could
be delivered, including the foundation
for vault 7, below, was completed in
just four and a half months. The vault at
the connection houses one of the two
84 in. diameter butterfly valves
used on the project.