Nitrogen Concentration (Tributaries)
Nitrogen is a nutrient important to the growth and reproduction of plants, and it is considered a pollutant of concern in the Lake Tahoe Region. Nitrogen and phosphorus together support the growth of algae in Lake Tahoe. Free-floating algae occur throughout Lake Tahoe and contribute to the decline in water transparency and attached algae coat rocks in the nearshore, adversely affecting nearshore aesthetics. Landscape disturbances including, but not limited to, impervious road and parking lot 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. Weather variations and their effects on stream hydrology (particularly the extremes of droughts and floods), and long-term climate change are considered among the most important environmental drivers of tributary runoff. This indicator measures the average concentration of total nitrogen for each water year in the seven streams in the Tahoe Region routinely monitored by USGS.
Status
Annual average total nitrogen concentrations for 2014 Water Year and status determinations relative to standard for each of the five regularly monitored California streams. The total nitrogen standard is a not to exceed standard, where percent to target values below 100% indicate the standard is in attainment.
Evaluation Map
Water Quality Monitoring Locations
2019 Evaluation
- Status
- Somewhat Worse Than Target
- Trend
- Moderate Improvement
- Confidence
- Moderate
Applicable Standard
WQ15: Attain applicable state standards for concentrations of dissolved inorganic nitrogen.
Key Points
- There has been a small reduction in overall nitrogen concentrations in monitored streams since monitoring became more widespread in 1988.
- Reducing nitrogen loading is critical because excess loading of nitrogen supports the growth of algae which is a driver of clarity decline.
Delivering and Measuring Success
Monitoring Programs