1970 – Las Vegas drinking water pipeline constructed across the Wash
The Las Vegas Lateral was constructed in 1970-1971 as part of the Southern Nevada Water Project, now known as the Robert B. Griffith project. The lateral was built as one of the distribution pipelines, which brought treated water into the Valley from Lake Mead, and extends seven miles from the outlet portal of the River Mountains tunnel, through the Henderson Bifurcation, to the Whitney Bifurcation. At that point the lateral ends, and the Whitney and North Las Vegas Laterals begin. The lateral was installed by trenching into the Wash, with the assistance of dewatering wells. Some disturbance to Wash bedding occurred during this process, and the U.S. Bureau of Reclamation was initially concerned with backfill compaction of new materials. However, compaction turned out to be better than or equal to what was previously there. The lateral, which is no longer in use, varied in diameter from 90-96 inches depending on location, and had a capacity ranging from 261-289 cubic feet per second (cfs).

Early 1970s – Increasing water flows and flood events cause 5,000 feet of upstream headcutting
By 1970, wastewater flows in the Wash had increased to approximately 25 mgd (39 cfs) and the Valley's population had grown to approximately 262,000 people. Urban coverage in the Valley had increased to approximately 40,000 acres by 1970, an 82 percent increase over the previous decade. These increasing wastewater flows continued to cut and destabilize the Wash during the 1970s. A 1975 flood event increased headcutting and, over the next four years, headcutting advanced 5,000 feet upstream. In 1975, marsh habitat was particularly noted to be in decline, and the amount of wetland vegetation (excluding tamarisk) along the Wash, from Desert Inn Road to Lake Las Vegas (constructed in the early 1990's), was roughly 1,420 acres. This provided an abundance of habitat for wildlife living in the Wash. At this time, there were only about 260 acres of tamarisk in the Wash. The Wash channel was often degraded sharply and suddenly during short-term surges of floodwaters from storm events. These floodwaters widened the channel, accelerated upstream migration of headcuts and contributed greatly to drainage and deterioration of the wetland vegetation.

1973 – Sewage and wastewater advisory committee is organized
In July 1973, the Sewage and Wastewater Advisory Committee (SWAC) was organized as required by NRS 244A. The SWAC was comprised of technical employees from municipalities or districts who were actively engaged in the operation or management of sewer or water facilities within Clark County to advise the Board of County Commissioners on wastewater issues.
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1973 – Clark County Water Reclamation District (CCWRD) constructs new wastewater treatment plant
In 1973, the CCWRD, located east of Boulder Highway on Flamingo Road, constructed their East Plant, thereby increasing total wastewater treatment capacity to 32 mgd. Both East and West Plants are primary sedimentation and trickling filters to provide secondary treatment to the Valley's wastewater.

1973 – Las Vegas Wash development advisory committee is organized to discuss wetland degradation issues
In 1973, a Las Vegas Wash Development Advisory Committee was organized by local citizens and representatives from various agencies for the purpose of making recommendations to the Board of County Commissioners on how to restore wetlands in the Wash. Because the committee was not in a position to make decisions, they later recommended to the Board that a Task Force be established to find solutions to erosion problems in the Wash. The Task Force was not established until 13 years later, in 1986.

1977 - 1978 – Section 208 water quality management plan issued
In April 1977, the first Section 208 water quality reports were published for Clark County. Four of the reports dealt with the following four Wash-related issues: Las Vegas Wash development and coordination with wastewater treatment facilities, salinity control, recreation and flood control aspects. A year later, in July 1978, the Clark County Board of Commissioners transferred water quality planning functions from the Clark County Water Reclamation District to the Clark County Department of Comprehensive Planning (Clark County Department of Air Quality and Environmental Management). That same year, the board adopted the Clark County 208 Water Quality Management Plan, which presented objectives, policies and programs for managing water quality in the county, including the Wash. Since 1978, there have been numerous amendments to the Section 208 Water Quality Management Plan.

1978 – Northshore road culverts replaced by Northshore bridge
Construction of the Northshore Bridge in 1978, where the Northshore Road crosses the Wash, replaced earlier installed culverts and allowed the headcutting to advance upstream even further. This headcutting would cause the need for reconstruction and deeper burial of the Las Vegas Lateral, a pipeline upstream beneath the Wash that carried water from Lake Mead to the Valley. At this time, headcutting and erosion had significantly reduced riparian wetlands and drained a substantial part of the shallow ground water reservoir beneath the floodplain of the Wash, which supported the wetlands.

1979 – Water Quality Study Board & Las Vegas Valley Water Quality Program formed Quality Program Formed
In March 1979, the Cities of Las Vegas and North Las Vegas, Clark County, the State of Nevada and the EPA entered into a Consent Decree agreeing on certain effluent limitations for the Wash and Lake Mead. It established a planning process to address other related issues such as treatment facilities planning, use of the Wash and reuse of effluent. A multiple jurisdictional planning board, the Water Quality Study Board, was formed to manage what would be new water quality standards and wastewater treatment facilities' planning efforts for the Valley. This program was called the "Las Vegas Valley Water Quality Program." The Water Quality Study Board was comprised of representatives from Clark County, the Cities of Las Vegas and North Las Vegas, the State of Nevada and the EPA. Their task was to be the governing body directing both water quality and treatment facilities' studies. The sunset for this board was June 1, 1981.