Early 1990s – Lake Las Vegas constructed
In the early 1990's, the entire flow of the Wash was diverted by construction of Lake Las Vegas. Wash flows were re-routed under the Lake through two large pipelines (i.e., conduits). Although this temporarily stopped channel erosion in the Wash along a reach of about two miles, subsequent flood flows intruded the clear-water lake, and severe erosion of the lower Wash continued upstream from Lake Las Vegas. By 1990, wastewater flows in the Wash had increased to approximately 93 mgd (145 cfs), the Valley's population had grown to approximately 708,000 people and urban coverage in the Valley had increased to approximately 124,000 acres. Additionally, in 1991, the City of Las Vegas Water Pollution Control Facility expanded its capacity to 66 mgd.

1991-1993 – Clark County begins planning for Wetlands Park
In 1991, Nevada residents approved a wildlife and parks bond (Question 5) earmarking $13.3 million for erosion control and construction of a Wetlands Park project in the Wash. Two years later, Clark County began work on a master planning process for the Wetlands Park. This process carefully examined current conditions in the Wash, solicited comments from the public about the desired future of the area and worked with various agencies to determine the type of uses to be accommodated.

1993 – Clark County begins planning for Pabco Road erosion control structure
During work on the Master Plan document, Clark County began preliminary design analysis in 1993 for the first of several erosion control structures to be built in the Wash, the Pabco Road Erosion Control Structure (ECS). Its primary purpose was to control headcutting and erosion, and to protect wetlands in a one mile reach of the Wash between Pabco Road and Duck Creek.

1994 – City of Henderson Water Reclamation Facility built
The City of Henderson Water Reclamation Facility was built in 1994. Three methods of treated effluent disposal were instituted: discharge to rapid infiltration basins, discharge to the Wash and delivery to the City's extensive water reuse system. Prior to this time, the City of Henderson discharged wastewater into rapid infiltration basins (not into the Wash).

1995 – Clark County Wetlands Park Master Plan finalized
In July 1995, Clark County Parks & Recreation (CCP&R) finalized the Master Plan for the Clark County Wetlands Park. The document defined strategies for development of the Wetlands Park, including creating a system of trails, interpretive exhibits, a visitor center and picnic areas along the Wash, as well as construction of about 15 erosion control structures. Along with defining these project components, the Master Plan discussed how the plan should be implemented and managed by using a three-phased development approach. The Master Plan outlined what the major focus of each phase should be, along with estimated costs of development. The Wetlands Park was estimated to be complete by 2015. By 1995, total acreage of wetland vegetation in the Wash had decreased considerably from what it was in 1985, while the amount of salt cedar continued to rise. This lessened the amount of suitable habitat for wildlife living in the Wash. In 1995, total acreage of wetland vegetation in the Wash (excluding salt cedar), from Desert Inn Road to Lake Las Vegas, was approximately 374 acres, which constituted a 70 percent reduction in wetland habitat for wildlife living in the Wash. The acreage of salt cedar had increased to 757 acres by this time.

1996 – Ownership transfer of grade control structure
On January 1, 1996, ownership of all facilities, structures, pipelines and loans was transferred from the CRC to SNWA. This included the abandoned Las Vegas Lateral, the new lateral and the Grade Control Structure.

1996 – Friends of the Desert Wetlands Park established
In March 1996, a non-profit organization called the Friends of the Desert Wetlands Park was officially established. The group formed for the purpose of organizing, developing and managing volunteer efforts to enhance the recreational uses, the natural, cultural and historical resources, and environmental maintenance of the Wetlands Park. Members currently work to strengthen and enhance opportunities for recreation use, interpretive understanding and appreciation of the Wetlands Park, and to protect and improve wildlife habitat.

1997 – Dam under Northshore bridge built and failed
During its construction phase, Lake Las Vegas offered to build a concrete-lined channel under the Northshore Bridge to handle floodwaters. However, at that time, the National Park Service (NPS) was concerned that a concrete channel would cause a headcutting problem at the end of the channel. NPS engineers analyzed many options to protect the bridge and at the same time create wetlands habitat. The idea of wetlands being created attracted the U.S. Bureau of Reclamation (USBR), which offered to design and construct two dam structures. Rock was provided by Lake Las Vegas, and one dam structure was constructed in 1997. Within 24 hours, water eroded through the dam and it failed. Engineers concluded that the dirt-filled, rock dam was not strong enough to hold the Wash water and, since then, there have been no funds available to replace the structure. In the following months, engineers redirected the flow of water between the Northshore Bridge's pillars. However, flood waters from a September 1998 flood event further eroded adjacent banks and damaged bridge abutments. Erosion continues to be a problem for the bridge today.

1997 – Lake Mead Water Quality Forum and Water Quality Citizens Advisory Committee established
In response to growing concerns over water quality issues in the Wash and Lake Mead, the Nevada Division of Environmental Protection (NDEP) initiated the Lake Mead Water Quality Forum in 1997. The Forum was comprised exclusively of local, state and federal agencies with an interest in environmental issues, water quality standards and identifying research needs.

Five months later, the Southern Nevada Water Authority (SNWA) established a 21-member Water Quality Citizens Advisory Committee to provide the Forum with public input and citizen recommendations. The citizens advisory committee was comprised of local citizens with an interest in water quality issues. Its mission was to develop specific recommendations to address and protect water quality in the Wash and Lake Mead. In 1998, the citizens advisory committee developed nine recommendations that were presented to the SNWA Board of Directors and the Forum for approval and implementation. One conclusion was that, because water quality issues related to the Wash are complex, they are not the responsibility of any one public entity. Thus, the committee suggested that an interagency and community-wide effort be developed and implemented in order to address the many issues surrounding the Wash. They also recommended that the effort be coordinated through the SNWA. The Lake Mead Water Quality Forum agreed, and this was the origin of the Las Vegas Wash Coordination Committee.

1998 – Las Vegas Wash Coordination Committee established
In October 1998, the SNWA developed and implemented the 28-member Las Vegas Wash Coordination Committee, comprised of local, state and federal agencies, members of the public, business people and representatives of environmental groups. The committee was charged with researching and analyzing issues related to the Wash and developing a comprehensive adaptive management plan that recommends solutions to problems. By 1998, total acreage of wetland vegetation (excluding salt cedar) in the Wash, from Desert Inn Road to Lake Las Vegas, was approximately 304 acres, a 79 percent decrease in wildlife habitat from what existed in 1975. The acreage of salt cedar in the Wash had increased to 1,021 acres by this time, and appears to be the result of salt cedar's ability to quickly establish itself in areas that have been eroded or scoured.

1998 – Emergency repairs to temporary erosion control structure
In July 1998, a cooperative agreement was signed between the SNWA and CCP&R to permanently repair the temporary GCS in an effort to reduce erosion and enhance wetland vegetation in the Wash. However, in September 1998, before final design was completed for the permanent GCS, a flood event damaged the temporary GCS and caused the need for the SNWA to conduct "emergency" repairs (before permanent repairs). Emergency repairs were completed in October 1998.

1998-1999 – Three severe flood events scour sediments from the Wash
Three flood events, in July 1998, September 1998 and July 1999 amplified channel erosion, advanced headcutting, removed second-growth salt cedar vegetation that replaced earlier wetland flora, destroyed the temporary GCS and intruded Lake Las Vegas. The September 1998 flood event alone caused 1 foot of vertical headcutting at Pabco Road, a surprisingly low amount; however, the channel was widened significantly and the temporary GCS was lost. The temporary GCS, as originally built, was designed to last two years. It was not designed to withstand a 100-year flood event and, during the three-year period from 1995-1998, suffered repeated damage by flood waters. Temporary repairs to the structure were made during this time by Lake Las Vegas.

1999 – Construction of two erosion control structures delayed by flood
In June 1999, final design was completed for the permanent GCS and the Pabco Road ECS. However, construction was delayed due to complications resulting from the most recent flood event, an intense summer storm that spread across the Valley on July 8, 1999. Sending more than 4.5 billion gallons of water through the Wash, the flood ripped into channel banks, washing everything down the channel, including the temporary GCS. Erosion widened the channel at various locations in the Wash by an average of 300 feet, destroying some remaining wetlands and carrying tons of sediment into Lake Mead. A month later, the SNWA and CCP&R initiated redesign of the permanent GCS and Pabco Road ECS, respectively. The flood event reinforced the urgency of constructing permanent grade control structures in the Wash. Both structures were completed in 2000.

Late 1999 – Current conditions
During 1999, the Wash exhibited peak flows (including stormwater) that exceeded the 100-year flood event estimated to be 12,700 cfs, while non-stormwater flows in 1997 were approximately 150 mgd (230 cfs). The Valley's population had increased to approximately 1.3 million people by 1999, with urban coverage at approximately 187,000 acres. Although these changes have affected the Wash dramatically by increasing erosion, the quality of wastewater discharged from treatment plants along the Wash has greatly improved since the 1970s. As a result, the quality of the water in the Wash today is probably better than it has ever been. In order to accommodate continued population growth in the Valley and increasing wastewater flows in the Wash, erosion and headcutting advancement must be controlled to protect wetlands, wildlife habitat, Wetlands Park facilities and adjacent developments.