FROM CONCENTRATION TO LOADING, FROM CONFLICT TO COLLABORATION: THE LAS VEGAS WASH WATERSHED TMDL STORY

This paper presents the history of the Las Vegas Valley Wash Watershed and the evolving relationship between the Nevada Division of Environmental Protection and the three major wastewater dischargers to the Las Vegas Wash, the Clark County Sanitation District, the City of Las Vegas and the City of Henderson (Dischargers).The Las Vegas Wash (Wash) is the single drainage way for metropolitan Las Vegas, which includes the City of Las Vegas, the City of North Las Vegas, the City of Henderson and a substantial urbanized area in the unincorporated area of Clark County. It drains 1,600 square miles of urban and rural watershed and is the discharge route for the wastewater treatment plants. The Wash drains the point and non-point discharges of 1.3 million residents and the 30 million people who visit Las Vegas on an annual basis. To further complicate matters, the Wash discharges into the Las Vegas Bay of Lake Mead, one of the premier recreational areas in the western United States and water supply to 18 million residents of the Southwest.In the 1970's, the State of Nevada and Clark County were some of the first entities to fully embrace the 1972 Clean Water Act. The Act was restated, in its entirety, in the Nevada Revised Statutes, and Clark County was designated as the master agency responsible for wastewater planning in the County and, specifically, in the Las Vegas Valley. Conflict occurred almost immediately when Clark County instituted planning guidelines, through the 208 process, that would require the City of Las Vegas to join the County in the construction and use of a regional Advanced Wastewater Treatment Facility. To add further complexity, substantial controversy surrounded the need for such a facility. Due to algae outbreaks in the late 1960's, the State of Nevada originally required a phosphorus standard of .05 mg/L, probably the most stringent standard at that time in the United States. Subsequently, the standard was raised to .1 mg/L, then .5 mg/L and finally to 1.0 mg/L. The raising of these standards was not voluntary on the part of either the Nevada Division of Environmental Protection, or the Environmental Protection Agency of the United States. A federal lawsuit was filed by the cities of North Las Vegas and Las Vegas versus Clark County, the State of Nevada and the Environmental Protection Agency.These lawsuits resulted in a number of studies, and eventually, a Consent Decree, where the courts set the 1.0-mg/L phosphorus standard. This standard was in place until the 1990's, when the State of Nevada, through the total maximum daily load (TMDL) process, set loading limits to the Las Vegas Bay for both phosphorus, and un-ionized ammonia. The TMDL was split into a Wasteload Allocation (WLA), which deducted 100 pounds of phosphorus for non-point sources. The WLA was originally shared between the City of Las Vegas and Clark County Sanitation District based on projected flows. In 1993, Clark County revised its 208 Water Quality Management Plan to include the City of Henderson discharging into the Las Vegas Wash. The State of Nevada approved the voluntary reapportionment of the WLA among the three dischargers in 1994. The WLA was once again voluntarily reapportioned in 1998 to readjust for growth changes in the three discharging agency service areas.Since the 1990's the three discharging agencies, along with the State of Nevada have recognized the need to work cooperatively to protect the Las Vegas Wash and Bay. This has resulted in a number of joint studies and a proposal for waste load trading among the Dischargers. Unprecedented in the State of Nevada, the new permit for the Dischargers will include the following provisions:Voluntary trading of WLA between and among the Dischargers. This would allow for pre-determined agreements among the Dischargers to treat each others sewage or to treat to high removal standards based on growth or facility treatment efficienciesA proviso in all three Dischargers' permits which would state that enforcement of the exceedance of an individual WLA would only be instigated in the event that the total WLA was exceeded.In 1999, the Dischargers became part of a Watershed Planning group known as the Las Vegas Wash Coordination Committee. This committee is comprised of 29 local, state, and federal agencies concerned with the water quality in the Las Vegas Wash Watershed. This committee has just completed a Comprehensive Adaptive Management Plan to address a wide range of concerns in the Wash for now and into the future on a community-wide basis.This paper will describe the events that lead to this historic change in the business practices of the Dischargers in the Las Vegas Valley, their relationship with the 208 Water Quality Agency and the delegated Clean Water Act agency, the Nevada Division of Environmental Protection.