Phosphorus is a nutrient important to the growth and reproduction of plants and is considered a pollutant of concern in the Lake Tahoe Region. Nitrogen and phosphorus together support the growth of algae in Lake Tahoe and contribute to the decline in water transparency and adversely affect nearshore aesthetics. Landscape disturbances including impervious surfaces, residential and commercial development, wildfire, and the degradation of stream environment zones (SEZs), can contribute to sediment and nutrient inputs to the lake or its tributaries. Projects such as restoring SEZ and limiting fertilizer use in the Region seek to reduce phosphorous in Lake Tahoe's tributaries.

2019 Evaluation

Insufficient Data to Determine Status or No Target Established
Insufficient Data to Determine Trend
Not available
View Evaluation

Applicable Standard

Reduce the loading of dissolved phosphorus to achieve pelagic water standards
(WQ1 and WQ2) and littoral quality standards (WQ5 and WQ6).

Key Points

  • The status of the standard is assessed as "insufficient data" because the monitoring programs assess total phosphorus load, and do not directly quantify dissolved phosphorus load.
  • At the September 2020 meeting of the Threshold Update Initiative Stakeholder Working Group, consistent with guidance from the Tahoe Science Advisory Group, the water quality standards related to load reduction were recommended to be removed as threshold standards and retained as Environmental Improvement Program performance measures.