BOARD00535

• Board Meeting Date: 5/22/2000
• Description: Colorado River Basin Issues - Colorado River ‎(Mainstem)‎ Director's Report
• Board Meetings - Doc Type: Memo

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Mountains \Vater Treatment
Facility, the $]47 million
project that includes the
controversial change order.
System-wide, the ongoing
work also includes the addi-
tion of 87 miles of pipeline
to the pre-existing 75 miles.
Some critics wonder why
the system's capacity is
being increased in excess of
Nevada's allocation of Col.
orado River water from
Lake Mead, SNWA recently increased the lake-intake
capacity from an initial 600 mgd to 1,200 mgd; and
boosted treatment capacity from 400 mgd to 600
mgd, with plans to expand it again to 900 mgd.
And such critics complain that use of the second
lake intake will exacerbate the possibility of drawing
water mixed with treated effluent. Federal policy
encourages Clark County-with its current 1.3 mil-
lion residents-to return treated effiuent to the lake.
Last year, Mulroy's agency obtained so-called return-
flow credits of ]60,000 acre-ft to augment a river
allocation of 300,000 acre-ft.
"We're essentially contami-
nating our own drinking.
water supply in the process
of collecting return-flow
credits," complains a retired
lakes expert Larry J. Paul.
son, 55, a fOrnler professor
in the biology department at
the University of Nevada,
Las Vegas.
Nevada's annual alloca-
tion of 300,000 acre-ft-
enough for 1.8 million peo-
ple-seemed more than
adequate in ] 928 when Con.
gress authorized construe.
tion of Hoover Dam to im-
pound Lake Mead. Before
construction began in ] 93],
when Nevada also legalized
gambling, Las Vegas sur.
vived as a rail stop. Natural
artesian springs made life
possible despite a mere 4 in.
of average annual rainfall.
Now the region hosts nearly
34 million tourists annually.

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LAKE INTAKE
The Las Vegas Valley
doubles Its lake-tap
capacity, down-
stream of Its emu-
ent discharge. To kill
any cryplosporldlum
In the Intake water,
the expanded Smith
and new River
Mountains plants
feature ozone units.

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The county and the cities of .
Las Vegas and Henderson emf>
ty ]20 mgd of effluent into Las
Vegas Wash, according to the
Clark County Sanitation Dis.
met. The discharge flows into
Lake Mead, 8 miles upstream of
Saddle Island where the region
draws 85% of its potable water.
Although tertiary-treated to
remove nuuients that nourish
algae, the effluent contains
more total dissolved salts than
the Colorado River. And with a
higher density than the lake,
the effluent flows as a plume. At
worst, according to Mulroy's
SNWA staff. a remnant of the
plume-less than a half meter
thick and 95% diluted-
remains when passing across
the pre-existing intake. Other
officials believe that some gets
sucked in. "] don't think any-
body knows for SUTe. ] think it's
safe to say that it may," says
Douglas W. Karafa, a Clark
County Sanitation District civil
engineer.
A cryptosporidWsis outbreak in
] 99!>-94 terrorized local AIDS
sufferers and others with weak-
ened immune systems, killing
41. The federal Centers for Dis-
ease Control and Prevention

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APRIL 24, 2000/ENR 63