National Park Service

Mojave Desert Network I&M

Streams & Lakes




The water resources of Lake Mead National Receration Area (LAKE) are all highly modified from their natural state and face multiple impacts to natural ecosystem process.. Las Vegas Wash is listed as highly contaminated or "impaired" under section 303(d) of the Clean Water Act, and negatively affects water quality of Las Vegas Bay and other portions of Lake Mead. The Virgin River and Muddy River, which drain agricultural areas, are also listed as impaired. Most of the flow of these rivers is diverted during irrigation season, and the flow into Lake Mead during these times consists largely of irrigation return flow. Current and projected future growth in human population in the region, with associated increased demands on water availability, increased recreational use, and increased point and non-point pollution will continue to threaten the ecological condition of LAKE water resources. The effects of these threats could be exacerbated by the effects of climate change.

Despite its relatively remote location and current high air and water quality, waterbodies in Great Basin National Park (GRBA) face several potential threats. Large-scale proposed groundwater pumping in Snake and Spring valleys adjacent to GRBA could impact park water resources. Plans to build two coal-fired power plants within 100 miles of the park were recently shelved, but the construction of such plants in GRBA's airshed remains a possibility. Since the subalpine lakes are known to have low buffering capacity, atmospheric deposition of pollutants could potentially acidify lakes. Climate change is expected to alter precipitation and snowmelt patterns, affecting stream and lake hydrology. Climate change may also affect the physical limnology of lakes by changing the period and timing of the ice-free period.

Monitoring Objectives

Regulatory issues:
  • What is the regulatory status of 303(d)-assessed waters within LAKE? Is the number of listed water bodies or listed water quality parameters changing over time?

  • What is the regulatory status of Nevada Class A streams (the classification used by Nevada to designate ONRWs) within GRBA? What is the condition and trend in water quality of GRBA Class A streams? Specifically, is there any evidence of declining water quality that would warrant a change in regulatory status?

Condition and Trends in Streams at GRBA:
  • What are long term trends in the quantity and seasonal patterns of stream discharge?

  • What is the status of and what are the trends in stream water chemistry?

  • What is the status of and what are the trends in stream macroinvertebrate assemblages in streams?

  • For perennial lakes within GRBA, are water levels, lake ice phenology, or water chemistry parameters that may reflect climate and atmospheric
Condition and Trends in Lakes at GRBA:
  • In subalpine lakes, are water levels or is the lake ice-free season changing over time?

  • What is the status of and what are the trends in lake water chemistry?

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Last Updated: December 04, 2012 Contact Webmaster