Benthic Index of Biotic Integrity (B-IBI) Implementation Strategy

The Benthic Index of Biotic Integrity (B-IBI) Implementation Strategy is designed to improve freshwater quality by analyzing the health and diversity of invertebrate populations in Puget Sound area streams.

Report cover
Report cover

Executive summary

The Puget Sound region has seen tremendous changes since the mid-1800s. Forested basins have been replaced with agricultural and urban developments, which has had far-reaching effects our rivers and streams. Changes in land use have often led to erosive stream-flows, excessive sedimentation, warm water temperatures, removal of streamside vegetation, and contaminated runoff. This Benthic Index of Biotic Integrity (B-IBI) Implementation Strategy outlines a series of actions, approaches, and interim results that are meant to reverse some of those impacts in order to restore and protect streams throughout the Puget Sound.

B-IBI is a measure of stream health based on the abundance and type of stream macroinvertebrates present at a site. Stream macroinvertebrates – the insects, snails, worms, etc. that live in the stream bed - vary in their sensitivity to environmental stressors, and therefore are excellent indicators of stream health. Highly degraded streams tend to support only the most tolerant types of macroinvertebrates and result in low B-IBI scores. Streams that support a diverse group of sensitive macroinvertebrates produce higher scores. B-IBI scores decline predictably along a gradient of land use intensity.

The B-IBI Implementation Strategy focuses on improving regional freshwater quality by achieving two specific targets of the Puget Sound Partnership’s Freshwater Quality Vital Sign. These stated B-IBI targets are:

  •         Protect – Maintain 100 percent of Puget Sound lowland stream drainage areas ranked as “excellent”
  •         Restore – Improve and restore at least 30 streams ranked as “fair” so that scores improve to “good”

This Implementation Strategy is the work of an Interdisciplinary Team (IDT) of regional experts in science and policy, with extensive experience developing and leading projects for the protection and restoration of Puget Sound streams. The IDT worked through a step-wise process that: 1) identified stressors (environment) and pressures (human), 2) highlighted the causes of the stressors and pressures, 3) identified the barriers that impede us from addressing the stressors and pressures, and 4) identified strategies, approaches, and actions that address the barriers. The IDT determined that the primary pressure affecting streams is increasing land use intensity focusing on the conversion of forests to agricultural, residential, commercial, and industrial land uses. The key stressors arising from these land use changes are altered hydrology, degraded riparian areas, degraded instream habitat, and degraded water quality.

The strategies

The IDT identified four broad strategies likely to improve stream condition. These are listed below.

Increased local capacity strategy: The objective of this strategy is to improve funding, staff capacity, and availability of decision support tools for local stormwater management programs.

Many jurisdictions lack the capacity, in terms of personnel and/or expertise, to implement stormwater management programs. This lack of capacity limits local governments from addressing the impacts of stormwater on a local and regional scale. This strategy calls for increased stormwater program funding and training, and it calls for more effective investment of limited resources. Funding would allow for increased staffing resources, training, and improved stormwater management tools and information resources.

Watershed planning strategy: The objective of this strategy is to promote multi-program and cross- jurisdictional planning on a coordinated watershed scale to maximize benefits from protection, mitigation and restoration.

Stream conditions are affected by local and watershed-scale pressures. The overall watershed condition may limit the extent of recovery from local restoration or mitigation activities. As such, restoration and protection activities have a better likelihood of success if implemented in a framework that considers the entire watershed. Watershed-scale planning is one key way of incorporating that framework.

The strategy is intended to protect and restore watershed function and habitat, encouraging the development of political will to support the planning and implementation of restoration and protection activities, and promote investments in recovery including monitoring and evaluation to improve our understanding of how to improve B-IBI scores.

Education and incentives strategy: The objective of this strategy is to encourage stormwater retrofits and source control activities that limit pollutants, and to encourage habitat restoration on privately owned properties through focused incentives supported by education.

Past development was built without stormwater controls and there are few regulatory mechanisms that address stormwater runoff from these legacy developments. Major redevelopment of a property generally triggers new stormwater retrofit requirements but the rate of mitigation through this mechanism is slow and stormwater retrofits are generally not required on private properties. The rate of stormwater retrofit and habitat restoration work on private land will likely increase with well-designed education and incentive programs.

This strategy is designed to increase stormwater retrofits and source control with focused incentives like technical assistance, financial assistance, and/or permitting advantages, and to increase the restoration of riparian in-stream and wetland habitats by leveraging opportunities to coordinate and concentrate existing and planned restoration investments.

Draft working lands strategy: The objective of this strategy is to reduce the risk to forests and agricultural areas of being converted to urban or suburban land uses, and to reduce ongoing impacts of working lands on stream health.

There is ample evidence that impacts on stream quality are commensurate with the extent of development in a given watershed. Therefore, there is benefit in preventing the conversion of working lands to other more intense land uses. The implementation of Best Management Practices (BMPs) on working lands can mitigate adverse impacts.

This working lands strategy is considered draft. The information the IDT received from key stakeholders and implementers indicated that a more comprehensive, integrated, working lands strategy effort is warranted. This strategy requires new regional coordination, stakeholder engagement, and conceptual development.

Moving forward

The publication of the B-IBI Implementation Strategy is a starting point. It does not identify every project and policy change necessary to achieve the recovery targets. It is intended to create a strategic framework to achieve ambitious goals. The Implementation Strategy should help guide and prioritize regional recovery actions, inform policy decisions, and identify ways to evaluate progress.

This Implementation Strategy must be updated to as new information comes available. A robust research and monitoring program is necessary to better understand the effectiveness of various actions and projects, and to support planning and prioritization. The results and lessons learned from research and monitoring should be considered when the Implementation Strategy is updated and revised. The Implementation Strategy must exist within an adaptive management framework.
Implementation of this strategy will be an ongoing challenge. It will require resources and coordination, political will, difficult conversations, and hard choices. We will need the Puget

Sound recovery community, including senior leadership within federal and state agencies, tribes, and other collaborators (the entire Puget Sound Management Conference) to chart the course ahead, and undertake the actions and activities that will lead to Puget Sound recovery. This Implementation Strategy is one example of the collective effort that will help us reach our recovery targets.

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