Phosphorus Concentration (Tributaries)
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, 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. This indicator measures the average concentration of total phosphorus for each water year in the seven streams monitored by USGS.
Status
Avereage phosphorous concentrations at Third Creek. Third Creek is the only site monitored that shows a significant trend over time. The other six sites monitored show no signficant trends.
Evaluation Map
Water Quality Monitoring Location
2019 Evaluation
- Status
- Considerably Worse Than Target
- Trend
- Moderate Improvement
- Confidence
- Moderate
Applicable Standard
WQ16: Attain applicable state standards for concentrations of dissolved phosphorus.
Nevada: the annual average concentration of total phosphates cannot exceed 0.05 mg/L
California: The annual average value and the 90th percentile value of total phosphorus cannot exceed 0.015 mg/L.
Key Points
- There is moderate improvement in overall phosphorous concentrations since monitoring began.
- Reducing phosphorus loading is critical because excess loading of phosphorus supports the growth of algae which is a driver of clarity decline.
Delivering and Measuring Success
Monitoring Programs