The Tahoe Decision Support System (TDSS) is a tool to help resource managers use the latest scientific information to make sound management decisions that maintain environmental and socioeconomic health. The system is being developed by a team of scientists from the Science Section of the USGS Western Geographic Science Center in conjunction with the Tahoe Regional Planning Agency (TRPA).

TDSS an Identified Need

The need for TDSS was identified in the Lake Tahoe Basin Watershed Assessment conducted by the USDA Forest Service (USFS). The report recommended that regulatory and management agencies within the Lake Tahoe Basin (Basin) work together using an adaptive management framework. Adaptive management is an approach that allows for learning and adjustment to occur while management and restoration actions are ongoing.

Optimizing the Basin's Long-Term Planning

Resource managers are challenged with the difficult task of executing policies that will optimize environmental and socioeconomic benefits. Decision support models are tools that better enable decision-makers to understand the factors driving a particular management decision and then predict the outcome and potential impacts of that choice. For example, creating more biking trails could improve recreational experiences, but might reduce the habitat of an endangered native species.  A decision support tool will show the potential positive socioeconomic impact of adding bike trails while evaluating the effects on the endangered species population.  TDSS will optimize Basin agency's long-term planning by incorporating environmental and socioeconomic considerations.

Building on Existing Work

TDSS will build upon existing related work, specifically a decision support tool called the Tahoe Constrained Optimization Model (TCOM). USGS in collaboration with TRPA, US Environmental Protection Agency (USEPA) and the Desert Research Institute (DRI) built the model in 2002. TCOM was developed to characterize the economic and environmental consequences of implementing specific land-use regulations. Specifically, it focused on the regulation of impervious coverage by granting or denying building permits in a single watershed (the UpperTruckee River Basin). TCOM sought to identify the optimal allocation of building permits that maximized the value of the region's land market while meeting TRPA's environmental objectives.

TDSS will expand beyond a single watershed and incorporate additional criteria for decision making in the Basin. It will examine a wider array of socioeconomic and natural resource management issues. It will also provide tools and methods for integrating and analyzing models, data and modeling results. 

The system will utilize TRPA's updated environmental threshold indicators to measure a scenario's likely impact. A scenario is comprised of an expected development footprint, an estimate of future population, a projection of future climate changes, and a set of management controls.  In 1982, TRPA adopted nine threshold categories including: water quality, air quality, soil conservation, wildlife habitat, fish habitat, vegetation, noise, recreation, and scenic resources. Each threshold category contains a number of specific indicators and standards that are used to track, evaluate, and report the attainment status of each threshold over time. These are currently being reviewed and updated. TDSS will utilize the updated indicators to characterize the likely outcomes of alternative scenarios.

Tool Available Now

The system has been developed in phases over the last few years. The first phase of the project focused on a small set of established scenarios including a "No-project Alternative".  Results of this scenario demonstrated the consequences of continuing to do business as usual, as described in the current regional plans and the Environmental Improvement Program, a list of projects aimed at improving the Basin's environmental health. 

Launching the TDSS Tool & More Information

Accessing this tool requires the Administrator to create a login.  Please Contact TIIMS for a user name and password.  Launch TDSS Tool.

For more information about TDSS you can also contact:

William M Forney
Environmental Geographer
Western Geographic Science Center
345 Middlefield Rd.
Menlo Park, CA  94025
(650) 329-4237
wforney@usgs.gov