The States of California and Nevada and the Federal government are currently involved in a sensitive controversy over the fate of Pyramid Lake and the Newlands Irrigation project. Truckee Meadows, which lies at the base of the Carson Range (a spur of the Sierra Nevada) approximately 30 miles northeast of Lake Tahoe, was studied with regard to its potential as a source for additional water for the system. Knowledge of the hydrology of the area permits evaluation of the effect of pumping ground water from the Meadows to augment the flow of the Truckee River. The study develops an understanding of the hydrology of this watershed and river system. Interaction between natural inflows, outflows, and extractions for use, both surface and ground water, are extremely complex and each component must be evaluated to understand the physical operation of the Meadows. Results of this investigation have permitted modeling of the area to quantify interactions of water moving in and through it.