Pyramid Lake, located 40 miles northeast of Reno, Nevada, is the geographic sink of the Truckee River Basin. The lake is primarily fed by the Truckee River, which is mostly composed of the outflow from Lake Tahoe. With no outlet, water is only able to leave Pyramid Lake by evaporation or sub-surface seepage causing the lake to have a salinity approximately one sixth of that of sea water.

Although Lake Tahoe discharges clear water, the Truckee River delivers more turbid waters to Pyramid Lake after traversing the steep Sierra terrain and collecting moderately silt-laden surface runoff. The Truckee River then collects urban storm water and municipal wastewater discharges from the Reno-Sparks region before reaching Pyramid Lake.

Starting in the mid-1980s, Pyramid Lake has been the focus of several water quality investigations because of the endangered species living within it, and because the water quality of the Truckee River is changing (Hogan et al., 1987).

In order to better understand how Pyramid Lake has and will continue to respond to climate change and changes in the quality and quantity of water delivered by the Truckee River, a UC Davis TERC Graduate Student, Sean Trommer, is calibrating the UC Davis Dynamic Lake Model and Water Quality (DLM-WQ) to simulate the physical, chemical, and biological processes of Pyramid Lake.

The sub-models contained within DLM-WQ allow it to simulate the physical, chemical, and biological processes occurring within Pyramid Lake from inflow and meteorological conditions for the simulated time period.

Calibration and validation of DLM-WQ is being performed using the long-term monitoring data set of the Pyramid Lake Paiute Tribe. Once the model is fully calibrated and validated it will improve understanding of the changes Pyramid Lake has experienced over time and how it is expected to change under expected climate change scenarios.

DLM-WQ has been calibrated and validated to simulate the hydrodynamic processes in Pyramid Lake from 2000 to 2015. Calibration of the nutrient, phytoplankton, zooplankton, and light penetration sub-models is currently underway.

Contact: Sean Trommer (sctrommer@ucdavis.edu)

This project is funded by the Pyramid Lake Paiute Tribe.