Aquatic Habitat Guidelines (AHG)

AHG Guiding Principles

Aquatic Habitat Guidelines are based on a number of guiding principles. These principles embody our ecological understanding about how ecosystems function, and our priorities for protecting aquatic systems. The Aquatic Habitat Guidelines Guiding Principles summarize current scientific understanding about how ecosystems work and reflect current resource agency policy and technical approaches to protect ecosystem functions. Documenting this scientific and technical understanding and policy will enable managers and project prponents to assess the effectivenenss of the Aquatic Habitat Guidelines to protect and restore salmonid as well as other aquatic and riparian habitats as scientific understanding improves through time. The guiding principles progress from general to topical statements. The general guiding principles are divided into two categories: ecosystem function and project planning implementation.

The guiding principles were developed by steering committee members of the Aquatic Habitat Guidelines program in the Departments of Fish and Wildlife, Transportation, and Ecology, as well as the Department of Fish and Wildlife's Habitat Program technical staff. Some principles were taken directly or expanded from other planning documents such as the Wild Salmonid Policy (WDFW, 1997), the Statewide Strategy to Recover Salmon (State of Washington, 1999), and Coastal Salmon Conservation: Working Guidance for Comprehensive Salmon Restoration Initiatives on the Pacific Coast (NMFS, 1996).

General Guiding Principles for Ecosystem Function:

1. Ecological processes create and maintain habitat function. These processes include:
   1. Geomorphic processes - the interaction of water, sediment, and wood that creates channel and shoreline structure. Geomorphic processes include bank and bed erosion, channel migration and evolution, sedimentation, debris influences, erosion, accretion, sediment transport, and fire.
   2. Biological processes (e.g., nutrient cycling, species interactions, riparian and upland vegetation dynamics, species mediated habitat forming processes such as beaver activity).
   
   Salmon and other aquatic organisms have evolved and adapted to use the habitats created by these processes. The long-term survival of naturally occurring populations of these species is dependant on the continuation of these processes.
   
   
2. Ecological processes create and sustain a suite of ecosystem characteristics and functions that include:
   1. Ecosystem complexity, diversity, and change;
   2. Ecological connectivity;
   3. Riparian interactions;
   4. Floodplain connectivity;
   5. Species diversity, adaptation, and survival;
   6. Water quality and water quantity;
   7. Invertebrate production and sustained food web function.
3. These characteristics and functions have biological value as well as economic, social, cultural, educational, and recreational values.
   
   
4. Because these characteristics and functions vary across and within watersheds, the use of local watershed information in planning and design will often lead to less risk of adverse project impacts. Natural processes that are protected and restored will minimize risk and provide sustainability to ecosystem functions.

   This principle is paraphrased from the State of Washington (1999):

   1. Maintain and restore the freedom of rivers and streams to move and change, especially during floods.
   2. Allow time for natural regenerative processes to occur and provide recovery of river and stream integrity.
   3. Protect the natural diversity of species and restore the natural diversity of habitats within river channels and riparian zones.
   4. Support and foster habitat connectivity.
   5. Tailor actions locally and to the whole watershed in the proper sequence of time and place. Match the system's potential and long term human commitment to stewardship of the system.

   The principle is also paraphrased from the National Marine Fisheries Service (1996):

   1. To ensure no net loss of habitat functions and to enable natural processes to occur unimpeded, actions should benefit ecological functions. Actions that adversely affect habitat should be avoided.
   2. Maintain habitats required for salmonids during all life stages from embryos and alevins through adults.
   3. Maintain a well-dispersed network of high-quality refugia to serve as centers of population expansion.
   4. Maintain connectivity between high-quality habitats to allow for reinvasion and population expansion.
   5. Maintain genetic diversity.

General Guiding Principles for Project Planning and Implementation:

1. A holistic approach to project planning employs ecologically relevant units of management, such as watersheds.
2. Our limited understanding of ecological processes and engineered solutions is addressed by using the best available science and erring on the side of caution in project management, design, timing, and construction.
3. A holistic approach to project planning recognizes and maintains geomorphic processes (e.g., channel migration, channel evolution, hydrologic changes, erosion, sedimentation, accretion, and debris influences).
4. Appropriate uses of riparian, shoreline, and floodplain systems through responsible land use practices can maintain natural processes and avoid adverse cumulative effects.
5. A holistic approach to compensatory mitigation and restoration is desirable; such an approach is based on local watershed conditions, and it strives to maintain or restore historical ecological functions.
6. Compensatory mitigation for adverse impacts has risk and uncertainty of success. To minimize such risk and uncertainty, adverse impacts are first avoided and then minimized. Unavoidable adverse impacts are addressed by compensating for losses.
7. Complete compensatory mitigation includes consideration of the project impacts over time (which usually extend beyond the completion of the project) and across the landscape (which often extends beyond the boundaries of the project).
8. Appropriate operating and maintenance procedures are necessary to insure that project objectives are fulfilled and adverse environmental impacts are minimized.
9. Monitoring and adaptive management are critical components of restoration, mitigation, and management activities.