USGS Collaborates on Maryland Healthy Watersheds Assessment Active
Issue: The Maryland Healthy Watersheds Assessment (MDHWA) establishes a framework to assess watershed health and vulnerability for Maryland waters and watersheds. The assessment is intended to inform watershed management decision-making to sustain the health of State-identified healthy watersheds, which have been defined in Maryland as the watersheds associated with its designated high-quality, Tier II waters.
The Chesapeake Bay Program, through its Maintain Healthy Watersheds Goal Implementation Team, has a goal of maintaining the long-term health of watersheds identified as healthy by its partner jurisdictions. Quantitative indicators are important to assess current watershed condition, track future condition, and assess the vulnerability of these state-identified watersheds to future degradation. The MDHWA is part of the Chesapeake Bay Program (CBP) partnership’s effort to sustain state-identified healthy waters across the 64,000 square mile Chesapeake watershed. The Maintain Healthy Watershed Goal Team is coordinated by the USGS, under the leadership of Renee Thompson, USGS Geographer and supported by USEPA, is providing tools for states and CBP partners to identify and sustain healthy waters and watersheds.
The USGS coordinated with the Goal Team to oversee the development of the Chesapeake Healthy Watershed Assessment (CHWA). The CHWA was conducted by TetraTech, with funding from the USEPA, released in 2020. The goal of the CHWA is to promote the improvement of Chesapeake watershed health through the visualization of its watershed health metrics. Users of CHWA access useful information to support watershed conservation strategies and identify signals of change in healthy waters and watersheds. Each state has different approaches to assess their healthy waters, so a more in-depth analysis was conducted in Maryland, which could be used in other jurisdictions.
The Maryland Study
This study was supported through a partnership with CBP, The Chesapeake Bay Trust, Maryland Department of Natural Resources, Maryland Department of the Environment, with USGS scientists and researchers serving to advise and oversee the project. The development of the MDHWA was awarded to and completed by TetraTech, Inc. through EPA’s CBP Goal Implementation Team Funding.
Many of the metrics compiled for MD assessment were provided by USGS scientists including recent data on land use and projected land use change, flow alteration, nutrient pollution loading estimates, and stream bank and sediment erosion metrics. Development of the MDWHA also afforded the opportunity to evaluate the predictive ability of watershed metrics to predict watershed health, using data from the Maryland Biological Stream Survey (MBSS) as response variables. Where MBSS data were available, the MDHWA analyses used these stream data to examine relationships between landscape variables and stream response (in terms of Fish Index of Biological Integrity [FIBI] and Benthic Index of Biological Integrity [BIBI]) to assess the predictive power of proposed metrics for use in modeling stream condition. These models can subsequently be used to predict (1) current stream condition for unsampled areas and (2) future stream condition under new predicted future landscape conditions.
Major Findings
The MDHWA establishes a framework to improve the understanding of past, present and future landscape conditions influencing watershed health and vulnerability within Maryland waters and watersheds. This state-specific assessment builds upon the completed Chesapeake Bay Healthy Watersheds Assessment, but also integrates state-specific data. Some of the unique findings include:
Demonstrating the value of using field observed data as proxy indices to indicate watershed health.
Previous CHWA efforts for estimating watershed health relied on the use of indices. These were derived by normalizing all the identified predictor variables and then using simple summations to derive subindices and an overall index of watershed health. This approach forces the assumption that all variables used in the index are equally important to watershed health, and additionally, that the sub-indices are of equal importance as well. For this project, we demonstrate the value of using field observed data as proxy indices to indicate watershed health. Maryland provided an opportunity to develop state-scale healthy watershed assessments due to the availability of statewide in-stream monitoring by the MBSS. The MDHWA analyses used these stream data to examine relationships between landscape variables and stream response (in terms of FIBI and BIBI) to assess the predictive power of proposed metrics for use in modeling stream condition. These models can subsequently be used to predict (1) current stream condition for unsampled areas and (2) future stream condition under new predicted future landscape conditions.
A model was developed to use the fish index of biological integrity data to predict conditions was used across the state (figure 7 from the report). The conditions were classified into good, fair, and poor. The existing Tier II watersheds in MD were plotted on the map. The analysis provides information on where watersheds with good conditions could be classified for future protection by MD. A similar model was developed based on stream index of biological integrity and can be found on page 30 of the report.
Improved assessment of, and factors affecting, watershed conditions
The predicted scores maps reveal specific areas in need of improvement, or conversely, areas within the healthy watershed that are doing well and should be maintained. The model provides a relative indication of different factors that affect the scores. For example, fish habitat is affected by multiple factors with sediment being the most influential. Sediment from upland agricultural areas and stream bank erosion, along with stream flow alteration were primary factors affecting fish habitat conditions. Across both the predicted FIBI and BIBI some metrics were found to be consistently important, specifically many of the streambank and streambed erosion metrics, sediment and nutrient developed from different land uses, related metrics, percent impervious and forest cover, as well as percent impervious within the riparian area.
Management Applications and Next Steps
The results from the MDHWA (such as shown on map) can be used to reveal specific areas in need of improvement (areas with poor or fair scores), or conversely, areas within the healthy watershed that are doing well and should be maintained (areas with good scores).
The Maintain Healthy Watershed GIT is expanding the MDHWA to the entire Chesapeake Bay watershed and will be building upon the findings and stakeholder recommendations. The CHWA 2.0 will include the following outcomes: updated metrics, integration of the Chesapeake basin-wide index of biotic integrity for stream macroinvertebrates, or “Chessie BIBI,” as a proxy for field observed data, USGS data related to conductivity, fish habitat and land use change data, improved visualization, analysis and filtering functionality to meet user needs, computed change statistics for appropriate metrics related to land use and vulnerability metrics, and user customized fact sheets that include the interpretation of results.
In addition, the CHWA 2.0 project will incorporate user needs and stakeholder input to assure that the decision support tools meet end user needs related to identifying trends in watershed health, applications for conservation and restoration targeting and a better understanding of stressors. Selected trends analyses will be used to quantify changes over time and examine vulnerability in healthy watersheds. In addition, the new CHWA 2.0 will incorporate new high resolution land use land cover data from 2013-2018 as well as metrics related to effective impervious surface.
The assessment is intended to inform watershed management decision-making to sustain the health of State-identified healthy watersheds, which have been defined in Maryland as the watersheds associated with its designated high-quality, Tier II waters. These assessments support the Chesapeake Bay Program Healthy Watersheds outcome by providing data to support management decision-making for maintaining the health of watersheds. In addition, the assessments help to:
- Assess current watershed condition
- Track condition over time
- Provide early warning signs – vulnerability to degradation
- Identify resiliency – ability to sustain good watershed health despite stressors
For More Information
The final report, “Maryland Healthy Watersheds Assessment: Applying Health and Vulnerability Assessments to Maryland’s Tier II Waters” published by contractor Tetra Tech, Inc. can be found here.
The CHWA application, a visualization tool and associated GIS data can be viewed here and will be refreshed in 2023. The goal of the CHWA is to promote the improvement of Chesapeake watershed health through the visualization of its watershed health metrics. Users of CHWA access useful information to support watershed conservation strategies and identify signals of change in healthy waters and watersheds.
Contact: Renee Thompson (rthompso@chesapeakebay.net), USGS, oversaw the effort and coordinates the Healthy Watersheds GIT.
- Overview
Issue: The Maryland Healthy Watersheds Assessment (MDHWA) establishes a framework to assess watershed health and vulnerability for Maryland waters and watersheds. The assessment is intended to inform watershed management decision-making to sustain the health of State-identified healthy watersheds, which have been defined in Maryland as the watersheds associated with its designated high-quality, Tier II waters.
The Chesapeake Bay Program, through its Maintain Healthy Watersheds Goal Implementation Team, has a goal of maintaining the long-term health of watersheds identified as healthy by its partner jurisdictions. Quantitative indicators are important to assess current watershed condition, track future condition, and assess the vulnerability of these state-identified watersheds to future degradation. The MDHWA is part of the Chesapeake Bay Program (CBP) partnership’s effort to sustain state-identified healthy waters across the 64,000 square mile Chesapeake watershed. The Maintain Healthy Watershed Goal Team is coordinated by the USGS, under the leadership of Renee Thompson, USGS Geographer and supported by USEPA, is providing tools for states and CBP partners to identify and sustain healthy waters and watersheds.
The USGS coordinated with the Goal Team to oversee the development of the Chesapeake Healthy Watershed Assessment (CHWA). The CHWA was conducted by TetraTech, with funding from the USEPA, released in 2020. The goal of the CHWA is to promote the improvement of Chesapeake watershed health through the visualization of its watershed health metrics. Users of CHWA access useful information to support watershed conservation strategies and identify signals of change in healthy waters and watersheds. Each state has different approaches to assess their healthy waters, so a more in-depth analysis was conducted in Maryland, which could be used in other jurisdictions.
The Maryland Study
This study was supported through a partnership with CBP, The Chesapeake Bay Trust, Maryland Department of Natural Resources, Maryland Department of the Environment, with USGS scientists and researchers serving to advise and oversee the project. The development of the MDHWA was awarded to and completed by TetraTech, Inc. through EPA’s CBP Goal Implementation Team Funding.
Many of the metrics compiled for MD assessment were provided by USGS scientists including recent data on land use and projected land use change, flow alteration, nutrient pollution loading estimates, and stream bank and sediment erosion metrics. Development of the MDWHA also afforded the opportunity to evaluate the predictive ability of watershed metrics to predict watershed health, using data from the Maryland Biological Stream Survey (MBSS) as response variables. Where MBSS data were available, the MDHWA analyses used these stream data to examine relationships between landscape variables and stream response (in terms of Fish Index of Biological Integrity [FIBI] and Benthic Index of Biological Integrity [BIBI]) to assess the predictive power of proposed metrics for use in modeling stream condition. These models can subsequently be used to predict (1) current stream condition for unsampled areas and (2) future stream condition under new predicted future landscape conditions.
Major Findings
The MDHWA establishes a framework to improve the understanding of past, present and future landscape conditions influencing watershed health and vulnerability within Maryland waters and watersheds. This state-specific assessment builds upon the completed Chesapeake Bay Healthy Watersheds Assessment, but also integrates state-specific data. Some of the unique findings include:
Demonstrating the value of using field observed data as proxy indices to indicate watershed health.
Previous CHWA efforts for estimating watershed health relied on the use of indices. These were derived by normalizing all the identified predictor variables and then using simple summations to derive subindices and an overall index of watershed health. This approach forces the assumption that all variables used in the index are equally important to watershed health, and additionally, that the sub-indices are of equal importance as well. For this project, we demonstrate the value of using field observed data as proxy indices to indicate watershed health. Maryland provided an opportunity to develop state-scale healthy watershed assessments due to the availability of statewide in-stream monitoring by the MBSS. The MDHWA analyses used these stream data to examine relationships between landscape variables and stream response (in terms of FIBI and BIBI) to assess the predictive power of proposed metrics for use in modeling stream condition. These models can subsequently be used to predict (1) current stream condition for unsampled areas and (2) future stream condition under new predicted future landscape conditions.
A model was developed to use the fish index of biological integrity data to predict conditions was used across the state (figure 7 from the report). The conditions were classified into good, fair, and poor. The existing Tier II watersheds in MD were plotted on the map. The analysis provides information on where watersheds with good conditions could be classified for future protection by MD. A similar model was developed based on stream index of biological integrity and can be found on page 30 of the report.
Sources/Usage: Public Domain. View Media DetailsResults of model used the fish index of biological integrity data to predict conditions was used across the state (figure 7 from TetraTech report). Improved assessment of, and factors affecting, watershed conditions
The predicted scores maps reveal specific areas in need of improvement, or conversely, areas within the healthy watershed that are doing well and should be maintained. The model provides a relative indication of different factors that affect the scores. For example, fish habitat is affected by multiple factors with sediment being the most influential. Sediment from upland agricultural areas and stream bank erosion, along with stream flow alteration were primary factors affecting fish habitat conditions. Across both the predicted FIBI and BIBI some metrics were found to be consistently important, specifically many of the streambank and streambed erosion metrics, sediment and nutrient developed from different land uses, related metrics, percent impervious and forest cover, as well as percent impervious within the riparian area.
Management Applications and Next Steps
The results from the MDHWA (such as shown on map) can be used to reveal specific areas in need of improvement (areas with poor or fair scores), or conversely, areas within the healthy watershed that are doing well and should be maintained (areas with good scores).
The Maintain Healthy Watershed GIT is expanding the MDHWA to the entire Chesapeake Bay watershed and will be building upon the findings and stakeholder recommendations. The CHWA 2.0 will include the following outcomes: updated metrics, integration of the Chesapeake basin-wide index of biotic integrity for stream macroinvertebrates, or “Chessie BIBI,” as a proxy for field observed data, USGS data related to conductivity, fish habitat and land use change data, improved visualization, analysis and filtering functionality to meet user needs, computed change statistics for appropriate metrics related to land use and vulnerability metrics, and user customized fact sheets that include the interpretation of results.
In addition, the CHWA 2.0 project will incorporate user needs and stakeholder input to assure that the decision support tools meet end user needs related to identifying trends in watershed health, applications for conservation and restoration targeting and a better understanding of stressors. Selected trends analyses will be used to quantify changes over time and examine vulnerability in healthy watersheds. In addition, the new CHWA 2.0 will incorporate new high resolution land use land cover data from 2013-2018 as well as metrics related to effective impervious surface.
The assessment is intended to inform watershed management decision-making to sustain the health of State-identified healthy watersheds, which have been defined in Maryland as the watersheds associated with its designated high-quality, Tier II waters. These assessments support the Chesapeake Bay Program Healthy Watersheds outcome by providing data to support management decision-making for maintaining the health of watersheds. In addition, the assessments help to:
- Assess current watershed condition
- Track condition over time
- Provide early warning signs – vulnerability to degradation
- Identify resiliency – ability to sustain good watershed health despite stressors
For More Information
The final report, “Maryland Healthy Watersheds Assessment: Applying Health and Vulnerability Assessments to Maryland’s Tier II Waters” published by contractor Tetra Tech, Inc. can be found here.
The CHWA application, a visualization tool and associated GIS data can be viewed here and will be refreshed in 2023. The goal of the CHWA is to promote the improvement of Chesapeake watershed health through the visualization of its watershed health metrics. Users of CHWA access useful information to support watershed conservation strategies and identify signals of change in healthy waters and watersheds.
Contact: Renee Thompson (rthompso@chesapeakebay.net), USGS, oversaw the effort and coordinates the Healthy Watersheds GIT.