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Draft Habitat Modifications White Paper

Category: Habitat - Habitat Conservation Plans

Date Published: December 28, 2007

Number of Pages: 318

Author(s): Herrera Environmental Consultants, Inc.


In 2006 and 2007, WDFW contracted with Anchor Environmental, Herrera Environmental Consultants, Jones & Stokes Associates, and R2 Resource Consultants to develop a series of “white papers” documenting the state of the science on a range of topics related to HPAs. The original white papers were peer-reviewed by a panel of experts outside of WDFW.

In developing the white papers, the consultants were working under specific time, scope, and cost constraints established by WDFW. These constraints were designed to further WDFW's specific goal of building a scientific foundation for a Habitat Conservation Plan for hydraulic projects that receive HPAs.

The white papers provide a solid scientific foundation upon which to build conservation measures for avoiding potential impacts, but they are not an exhaustive review of every potential impact of hydraulic projects. Rather, they reflect WDFW’s goal of establishing a solid scientific foundation for the HCP with limited time and financial resources.

Despite these constraints, WDFW is confident that a large proportion of the current scientific literature has been incorporated into the white papers. As WDFW continues to develop the Habitat Conservation Plan, we will also continue to assess new science, fill data gaps, and listen to the advice of scientists and hydraulic project construction specialists.


The Revised Code of Washington (RCW) directs the Washington Department of Fish and Wildlife (WDFW) to “preserve, protect, perpetuate, and manage” the fish and wildlife species of the state as its paramount responsibility (RCW 77.04.012). Under RCW 77.55, any construction or work that uses, diverts, obstructs, or changes the natural bed or flow of state waters requires a Hydraulic Project Approval (HPA) issued by WDFW. The purpose of the HPA program is to ensure that hydraulic projects are completed in a manner that prevents damage to public fish and shellfish resources and their habitats. To ensure that the HPA program complies with the Endangered Species Act (ESA), WDFW is developing a programmatic multispecies Habitat Conservation Plan (HCP) to obtain an Incidental Take Permit from the U.S. Fish and Wildlife Service (USFWS) and the National Oceanic and Atmospheric Administration (NOAA) Fisheries Service (also known as NOAA Fisheries), in accordance with Section 10 of the ESA. For WDFW, the objective is to ensure that activities conducted under an HPA avoid and/or minimize the incidental take of aquatic species considered for coverage under the HCP (referred to in this white paper as “HCP species”).

The HCP will address the impacts, potential for take, and mitigation measures for effects on HCP species from hydraulic projects that require HPAs. WDFW’s intent is to build the scientific foundation for the effort to prepare an HCP for hydraulic projects that receive HPAs. To accomplish this, WDFW is compiling the best available scientific information related to the impacts, potential for incidental “take” of species that may be covered in the HCP (as defined in the ESA; see Section 9 of this report for a definition of “take”), and possible management directives and mitigation measures to avoid and/or minimize potential take to the maximum extent practicable. As the Hydraulic Project Approval authority covers all waters of the state, this white paper considers hydraulic project impacts in both freshwater and marine environments.

This white paper is one of a suite of white papers prepared to establish the scientific basis for the HCP and assist WDFW decision-making on what specific HPA activities should be covered by the HCP. This particular white paper compiles and synthesizes existing scientific information on habitat modifications. This broad activity type includes the following subactivity types:

  • Beaver Dam Removal/Modifications
  • Large Woody Debris Addition/Removal
  • Spawning Substrate Augmentation
  • In-Channel/Off-Channel Habitat Modifications
  • Riparian and Estuarine Planting/Restoration
  • Wetland Creation/Restoration/Enhancement
  • Beach Nourishment/Contouring
  • Reef Creation
  • Eelgrass and other Aquatic Vegetation Enhancement.

In reviewing the best available scientific information regarding these activities it is the intent of this white paper to:

  • Compile and synthesize the best available scientific information related to the potential human impacts on HCP species, their habitats, and associated ecological processes resulting from the construction and presence of the aforementioned habitat modification project types.
  • Use this scientific information to estimate the circumstances, mechanisms, and risks of incidental take potentially or likely to result from the construction and presence of habitat modification projects.
  • Identify appropriate and practicable measures, including policy directives, conservation measures, and best management practices (BMPs), to avoid, minimize, or mitigate the risk of incidental take of HCP species.

The literature review conducted for this white paper identified six impact mechanisms that could potentially affect those aquatic species considered for coverage under the HCP (referred to as “HCP species”). These mechanisms of impact are both direct and indirect and can have temporary, short-term effects or permanent, long-term effects. The impact mechanisms analyzed in this white paper are:

  • Construction activities
  • Hydraulic and geomorphic modifications
  • Ecosystem fragmentation
  • Aquatic vegetation modifications
  • Riparian vegetation modifications
  • Water quality modifications.

This white paper presents an overview of what is known about the potential impact mechanisms in relation to the 52 species considered for HCP coverage (i.e., the HCP species). Based on a separate analysis conducted using exposure-response matrices for each species, the risks of direct and indirect impacts on these species and their habitats are identified and described. This white paper also reviews data gaps and estimates risk of take, as well as provides habitat protection, conservation, mitigation, and management strategies that could avoid or minimize the identified potential impacts. Key elements of the white paper are:

  • Identify the distribution of HCP species (i.e., whether they use fresh water,marine water, or both) and the habitat requirements of HCP species.
  • Identify the risk of “take” associated with impact mechanisms based on the distribution information.
  • Identify cumulative impacts.
  • Identify data gaps.
  • Identify habitat protection, conservation, and mitigation strategies.