Recent Progress: Increase
The most recent data for 2012-2017 shows stream health has improved about 6% from the baseline period of 2006-2011. The overall percentage of the Bay watershed stream miles estimated to support healthy streams was 67.8% during the 2012-2017 interval, continuing an overall positive trend that began in the pre-baseline period (2000-2005).
Outlook: On Course
Though some areas of the watershed show degrading trends, the net improving trend suggests the collective impact of multiple environmental stressors on streams may be slowly lessening in many parts of the Chesapeake watershed. While this supports the assessment that progress toward this outcome will continue to trend upward and meet the target of 10% improvement above the baseline, pandemic-related interruptions in state monitoring schedules during 2020 and 2021 may impact our ability to see detectable trends. Metrics for a variety of environmental stressors are currently being explored and will help future investigations of stream macroinvertebrate responses to identified stressors and can help explain the observed trends.
Biological communities can be used to infer the health of a stream because their composition reflects the impacts of multiple stressors from both land and water. The Chesapeake Basin-wide Index of Biotic Integrity, or Chessie BIBI, describes the biological quality of macroinvertebrate communities in assessed streams in relation to all the streams in the watershed. When a sampling site receives a Chessie BIBI score above a bioregion-specific reference threshold, which is the tenth percentile of all scores in that bioregion’s reference populations, it is considered in fair, good or excellent condition. When it receives a score that is below that threshold, it is ranked poor or very poor. All samples within a single subwatershed are given equal weight and their average score is used to rank the subwatershed’s overall stream condition.
Gaps in the monitoring data’s spatial and temporal coverage make it difficult to directly estimate percentages of healthy streams in the pre-baseline (2000-2005), baseline (2006-2011), and first interval (2012-2017) periods. However, statistical analyses of the available data indicate that approximately 61.7% (~89,317 miles) of non-tidal stream miles were rated fair, good or excellent condition in the baseline period, increasing to 67.8% in the first interval.
When the data are extrapolated to the entire watershed, stream biological health across each of the categories of fair, good, and excellent showed increases for each of the three time periods, while poor and very poor categories decreased. This trend, showing continual improvement over time, may be due to the long-term efforts to conserve forests, preserve and restore riparian corridors and wetlands, mitigate acid rain and mine drainage, slow stormwater runoff, and reduce nutrients and sediment loads. However, there is significant regional variability and some areas of the watershed, especially urban areas, show degrading trends. The workgroup is exploring additional metrics for a variety of environmental stressors to help future investigations characterize Chesapeake watershed health and assess the reasons for the current trends.
Restoring the health of rivers and streams benefits fish, wildlife and people and is a key step toward improving water quality in the Bay.
To achieve this outcome, Chesapeake Bay Program partners have committed to:
- Identifying an appropriate suite of metrics to measure the multiple facets of stream health and complement the Chesapeake Basin-wide Index of Biotic Integrity (or Chessie BIBI).
- Providing adequate financial and technical resources to support a functional lift in stream restoration projects and nutrient and sediment reductions.
- Improving coordination with stakeholders (e.g., natural resource agencies, stream and wetland permitting authorities, researchers, designers, local governments and non-profit organizations) to facilitate and expand local participation in stream restoration.
- Developing and promoting holistic stream restoration design guidelines that identify the level of degradation, the improvement of stream function and the factors limiting potential uplift.
- Enhancing the capacity of local governments, organizations and landowners to restore and maintain stream health.
Monitoring and assessing progress toward the outcome will occur through data related to physical, chemical and biological stream conditions and stream function.
As part of the Chesapeake Bay Program’s partnership-wide implementation of adaptive management, progress toward this outcome was reviewed and discussed by the Management Board in August of 2021. It will be reviewed and discussed by the Management Board again in November 2023.
Logic & Action Plan
Chesapeake Bay Program partners have committed to taking specific actions to achieve the high-level approaches identified in the management strategy above.
- Identifying practicable metrics for use in assessing overall improvements in stream health, in accordance with existing guidance for crediting both pollution reductions and improvements in the function of streams.
- Supporting the expansion of stream health monitoring efforts throughout the watershed.
- Training and educating stakeholders on stream restoration and health.
- Reported the monitoring-based Chessie BIBI results for 2012-2017, calculated by both stream miles and watershed area, via the Interstate Commission on the Potomac River Basin.
- Constructed an updated Chessie BIBI database (version 3.01).
Participating partners include:
- Delaware Department of Natural Resources and Environmental Control (State of Delaware)
- Maryland Department of the Environment (State of Maryland)
- Johns Hopkins University (State of Maryland)
- Maryland Water Quality Monitoring Council (State of Maryland)
- Maryland State Water Quality Advisory Committee (State of Maryland)
- University of Maryland Center for Environmental Science (State of Maryland)
- Maryland Department of Natural Resources (State of Maryland)
- New York Department of Environmental Conservation (State of New York)
- Pennsylvania Department of Environmental Protection (Commonwealth of Pennsylvania)
- Fairfax County (Commonwealth of Virginia)
- West Virginia Department of Environmental Protection (State of West Virginia)
- District Department of Energy and Environment (District of Columbia)
- Natural Resources Conservation Service (U.S. Department of Agriculture)
- U.S. Forest Service (U.S. Department of Agriculture)
- U.S. Army Corps of Engineers
- U.S. Environmental Protection Agency
- U.S. Fish and Wildlife Service
- U.S. Geological Survey
- Center for Watershed Protection
- Chesapeake Bay Trust
- Chesapeake Bay Foundation
- Ecosystem Services
- Headwaters LLC
- Interstate Commission on the Potomac River Basin
- Izaak Walton League
- McCormick Taylor
- National Fish and Wildlife Foundation
- Severn Riverkeeper
- Upper Susquehanna Coalition