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Early
1980s – Headcutting advances 9,000 feet upstream
By 1980, wastewater flows in the Wash had increased to approximately 58 mgd (90 cfs),
the Valley's population had grown to approximately 444,000 people and urban coverage in
the Valley had increased to approximately 91,000 acres. By the mid-1980s, wastewater
flows in the Wash had grown to average 100 cfs, and many erosional headcuts were active
along the six-mile reach of the lower Wash, from Pabco Road to Lake Mead. From 1979 to
1984, headcutting advanced 9,000 feet upstream and severe erosion continued throughout
the decade, even during times of minimum flow. In 1982, total acreage of marsh habitat
in the Wash had been reduced 80 percent, from what it was in 1975. During the same period,
salt cedar increased dramatically throughout the entire Wash. Three years later, in 1985,
total wetland vegetation (excluding tamarisk) in the Wash, from Desert Inn Road to Lake
Las Vegas (constructed in the early 1990s), covered approximately 1,260 acres. This was
a decrease of 160 acres from 1975, a 12 percent decrease. Acreage of tamarisk was
approximately 579 acres in 1985.
1982
– Clark County board approves master planning efforts for the Wash
On Sept. 3, 1982, a preliminary master plan was completed by Clark County Departments of
Parks & Recreation and Comprehensive Planning (Clark County Department of Air Quality and Environmental Management)
and approved by the Clark County Board of
Commissioners. There was considerable agency and public involvement during development of
the document, which was largely the result of efforts of the Las Vegas Wash Development
Advisory Committee.
1982
– Clark County Advanced Wastewater Treatment Plant constructed
To meet water quality standards, as well as the increasing needs of wastewater
treatment for the Valley, the Clark County Advanced Wastewater Treatment Plant
(AWT) was constructed in 1982 for the purpose of providing additional treatment
of wastewater in order to better protect the Wash and Lake Mead. The AWT provided
a wastewater treatment capacity of 90 mgd and further treated effluent from the
existing CCWRD East and West Plants by using chemical coagulation and filtration
to remove phosphorus from the wastewater.
1984
– Flood events erode more sediment from the Wash; temporary erosion
control structure built to protect drinking water pipeline
During the summer of 1984, there were multiple flash floods caused by a
prolonged monsoonal period, resulting in more than 4.25 million cubic yards
of sediment being transported to Lake Mead -- more than the equivalent amount
of concrete required to build Hoover Dam. These flood events caused the numerous
erosional headcuts to be integrated and greatly widened the flowpath, thereby
transforming the channel into a continuous trench from Pabco Road to the mouth
at Lake Mead. The Wash suffered extensive damage in July 1984 as peak flows
reached some of the highest levels on record. During the next four years,
headcutting advanced more than 4,400 feet upstream. This severe erosion
effectively completed destruction and drainage of most of the wetlands
downstream from Pabco Road.
A temporary Grade Control Structure (GCS) was built in 1984 by the Colorado River
Commission (CRC) to protect the Las Vegas Lateral, the pipeline carrying potable
water from Lake Mead to the Valley, buried beneath the Wash. The GCS was built as
a temporary means of protecting the lateral when erosion threatened its viability.
The GCS was designed to last for approximately two years, but actually remained in
the Wash (with frequent repairs) until 1999.
1985
– Clark County Regional Flood Control District created
In 1985, the Nevada Legislature created the Clark County Regional Flood
Control District (CCRFCD) for several purposes: to develop a coordinated and
comprehensive Master Plan to address flooding problems, regulate land use in
flood hazard areas, fund and coordinate construction of flood control facilities
(including facilities in the Wash), and develop and contribute to funding of a
maintenance program for the Master Plan's flood control facilities.
1986
– Temporary grade control structure is maintained
After investigating the most feasible and cost-effective method of protecting the Las
Valley Lateral from even further erosion, the CRC decided in 1986 to relocate a portion
of the lateral in a tunnel below the Wash. Soon after this decision, the USBR recommended
to CRC that the retired portion of the pipeline and temporary GCS be disposed upon relocation
of the lateral for the purpose of ensuring public safety and eliminating potential liabilities.
However, upon hearing USBR's recommendation, Clark County advised CRC that either Clark County or
the Clark County Regional Flood Control District (CCRFCD) may have an interest in acquiring the
temporary GCS for the purpose of avoiding further erosion in the Wash. At this time, CRC entered
into an agreement with Lake Las Vegas for interim operation and maintenance of the structure
(conducted by Lake Las Vegas). Ownership transfer of the GCS did not take place until it was
transferred to SNWA in January 1996.
1986
– Clark County establishes task force to address erosion in Wash
Clark County established a Task Force in 1986 to find solutions to erosion problems
in the Wash. The severity of problems was recognized as the result of a number of
factors: 1) the CRC spent more than $9 million to bury a new lateral (the Las Vegas
Lateral was exposed during the 1984 flooding), 2) increases in ammonia levels in Lake
Mead caused the State Environmental Commission to pass a resolution calling for Clark
County to restore the wetlands in the Wash, which had been helping to polish wastewater
entering Lake Mead, and 3) owners of other structures in the Wash, such as the Silver Bowl
and private developments near Duck Creek, voiced concerns that their structures might be
damaged by future erosion in the Wash.
The Task Force determined that
the best source of funding for an erosion control plan for the Wash was to seek authority from the
Nevada State Legislature to add a water surcharge. As a result, in March 1987, Nevada State Senate
Bill No. 243 was proposed. The bill was to impose a fee on water users from the Colorado River to
provide money for the maintenance of the Wash and require that the money be used to control erosion
and preserve the quality of water in the Wash. The bill never gained enough support to pass and
become law.
1988-1989
– Integrated & Comprehensive Management Program developed
In 1988, Clark County established the Las Vegas Wash Integrated and Comprehensive Management
Program (ICMP). The primary goal of this program was to control the ongoing natural resource
degradation while capitalizing on the many unique opportunities available within the Wash.
The ICMP identified four priority focus elements: 1) erosion control, 2) flood control, 3)
development of a Wetlands Park, and 4) wastewater treatment. One year later, Clark County
formulated a component of the ICMP, an Erosion Mitigation Plan, that recommended a system
of erosion control structures and other practices to reduce erosion in the Wash.
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