Lake Tahoe Basin Source Control Demonstration and Development Program Michael Hogan Integrated Environmental Restoration Services Partners: UC Davis, Caltrans, Integrated Environmental Restoration Services, Nevada State Lands, US Forest Service, California Conservation Corps (with Desert Research Institute, Lake Tahoe Environmental Education Coalition and Nevada Conservation Corps) Abstract Eroding hillslopes pose a serious threat to water quality and clarity in the Lake Tahoe Basin. While a great deal of attention has been paid to restoration of wetlands and riparian systems, little effort has been focused on the largest part of the watersheds: the upland areas that produce sediment. The Lake Tahoe Basin Source Control Demonstration and Development Program is focusing on development and demonstration of principles and practices that successfully restore upland slopes so that sediment is not delivered to watercourses and thus to Lake Tahoe. This program has been developed within an adaptive management context and is attempting to coordinate top-level scientists and practitioners who are focused primarily on finding solutions to upland water quality issues. This program is the first of its kind in the Tahoe Basin that is attempting to integrate a large number of ecosystem components into science-based practices that produce measurable results. This program looks at a functional soil system as the foundation of erosion control and is attempting to identify those components of that system that will provide the most effective erosion control possible. The program includes the following components: Definition of ÔsuccessÕ in an erosion-impacted soil-plant ecosystem Identification of missing components of disturbed systems Development of materials and methods that replace, restore or bootstrap ecosystem functions on disturbed sites, thus providing an effective level of functional erosion control Use of rainfall simulation to measure erosion resistance on treated areas (real-time, treatment effectiveness data) Development of a cost-effective monitoring program that actually measures effectiveness of treatments over time. This monitoring protocol relates directly to the ÔsuccessÕ criteria (above). Due to the complex and interactive nature of erosion processes with soil, plants and human activity, a numerical, science-based developmental process or program is needed in order to understand the technical components of upland erosion in the Tahoe Basin. The Development and Demonstration program is designed to integrate and continually improve technical methods of stabilizing and restoring disturbed upland areas with realistic, site adapted field methods so that N-and P-rich sediments remain at their source and intact, upland soils in the Tahoe Basin.