EDT in Action

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What is EDT

Habitat Assessment

Habitat Description

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Subbasin Assessment

Ecosystem Diagnosis and Treatment (EDT)

The EDT method was designed to provide a practical, science-based approach for developing and implementing watershed plans. The method provides decision makers with the technical information needed to develop plans that will achieve their goals. EDT has been used to develop fish and wildlife plans for many watersheds throughout the Pacific Northwest.

A publicly accessible version of EDT for the Columbia River is available at http://www.mobrand.com/edt.

The EDT method consists of three components:

• Conceptual Framework-a way of organizing information to describe a watershed ecosystem in order to apply scientific principles to the understanding of that ecosystem
• Analytical Model-a tool used to analyze environmental information and draw conclusions about the ecosystem
• Step-by-Step Procedure-a procedure that explains how to apply the conceptual framework and analytical model to develop plans that achieve goals.

The six basic steps of EDT are:

1. Identify objectives
2. Perform analysis and diagnosis
3. Formulate treatments
4. Describe benefits and risks (trade-off analysis)
5. Refine project objectives
6. Apply treatments, monitor, and evaluate

The conceptual framework for the EDT method was developed with an aim toward utility for salmon management but also with the important goal of maintaining consistency with an ecosystem approach. The framework accomplishes this by viewing salmon as the indicator, or diagnostic, species for the ecosystem. The salmon's perspective-its perception of the environment-becomes a filtered view of the system as a whole. Within the limitations of the salmon's perspective and our ability to interpret it, this approach provides a framework for formulating strategies for salmon in the context of watershed management.

The EDT framework was designed so that analyses made at different scales-from tributary watersheds to successively larger watersheds-might be related and linked. Ultimately, conditions within these watersheds are linked to those within the marine environment (Puget Sound and the North Pacific).

Biological performance is a central feature of the framework. It is defined in terms of three elements-life history diversity, productivity, and capacity. These elements of performance are characteristics of the ecosystem that describe persistence, abundance, and distribution potential of a population.
The analytical model is the tool used to analyze environmental information and draw conclusions about the ecosystem. The model incorporates an environmental attributes database and a set of mathematical algorithms that compute productivity and capacity parameters for the diagnostic species.

The general approach for comparing existing and desired conditions is called the Patient-Template Analysis (PTA). This approach compares existing conditions of the diagnostic populations and their habitat (patient) with a hypothetical potential state (Template), where conditions are as good as they can be within the watershed. The Template is sometimes approximated with a reconstruction of historic conditions. Sufficient information normally exists to do this with the level of clarity needed for the analysis. The Template is intended to capture the unique characteristics and limitations of the watershed due to its combination of climate, geography, geomorphology, and history.

The diagnosis is performed by comparing the Patient and Template to identify the factors or functions that are preventing the realization of objectives. The diagnosis can be qualitative or quantitative, depending on the type and quality of the information used to describe the ecosystem. Regardless, the diagnosis forms a clear statement of understanding about the present conditions of the watershed as related to the diagnostic species.

Following the diagnosis, potential actions to achieve goals are identified. Candidate actions are tailored to solve problems that were identified in the diagnosis.

Restoration plans are comprehensive, long-term plans for the entire ecosystem-they consist of suites of actions designed to meet goals. One of the main benefits of the EDT method is that it allows us to build diverse suites of actions and analyze their cumulative effects.