«ALABAMA & MOBILE BAY BASIN INTEGRATED ASSESSMENT OF WATERSHED HEALTH A Report on the Status and Vulnerability of Watershed Health in Alabama and the ...»
ALABAMA & MOBILE BAY BASIN
INTEGRATED ASSESSMENT OF WATERSHED HEALTH
A Report on the Status and Vulnerability of Watershed Health in
Alabama and the Mobile Bay Basin
ALABAMA & MOBILE BAY BASIN INTEGRATED ASSESSMENT OF WATERSHED HEALTH
Prepared by The Cadmus Group, Inc. for U.S. Environmental Protection Agency
Support for this project was provided by the US EPA Healthy Watersheds Program (http://www.epa.gov/healthywatersheds) Disclaimer The information presented in this document is intended to support screening level assessments of watershed protection priorities and is based on modeled and aggregated data that may have been collected or generated for other purposes. Results should be considered in that context and do not supplant site-specific evidence of watershed health or vulnerability.
At times, this document refers to statutory and regulatory provisions, which contain legally binding requirements. This document does not substitute for those provisions or regulations, nor is it a regulation itself. Thus, it does not impose legally-binding requirements on EPA, states, authorized tribes, or the public and may not apply to a particular situation based upon the circumstances.
Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government, and shall not be used for advertising or product endorsement purposes.
Cover photos courtesy of Rick Dowling (Left: Hatchet Creek, Coosa County) and Randy Shaneyfelt (Upper Right: Pitcher plants in headwater sloped wetlands, Baldwin County; Lower Right: Barrow Creek, headwater coastal stream in Mobile County)
ACKNOWLEDGEMENTSThis document was prepared by The Cadmus Group, Inc. under contract with the U.S. Environmental Protection Agency (EPA), Office of Water, Office of Wetlands, Oceans, and Watersheds. The following individuals are acknowledged for their contributions to project planning, data acquisition, and review of draft
Mary Kate Brown, The Nature Conservancy Scott Brown, Alabama Department of Environmental Management Ashley Campbell, City of Daphne Marlon Cook, Geological Survey of Alabama Mike Dardeau, Mobile Bay National Estuary Program Science Advisory Committee Beth Darrow, Dauphin Island Sea Lab Gary Davis, U.S. EPA Region 4 Dennis Devries, Mobile Bay National Estuary Program Science Advisory Committee Laura Gabanski, U.S. EPA Office of Water Tom Herder, Mobile Bay National Estuary Program Phillip Hinesley, Alabama Department of Conservation and Natural Resources Joie Horn, Alabama Department of Environmental Management Lisa Huff, Alabama Department of Environmental Management Allison Jenkins, Alabama Clean Water Partnership Chris Johnson, Alabama Department of Environmental Management Steve Jones, Geological Survey of Alabama Latif Kalin, Mobile Bay National Estuary Program Science Advisory Committee Ashley McDonald, Dauphin Island Sea Lab Owen McDonough, U.S. EPA Office of Water Amy Newbold, U.S. EPA Region 4 Mark Ornelas, Alabama Department of Environmental Management John Pate, Alabama Department of Environmental Management Scott Phipps, Weeks Bay National Estuarine Research Reserve Jon Porthouse, National Fish and Wildlife Foundation Jennifer Pritchett, U.S. Fish and Wildlife Service Mitch Reid, Alabama Rivers Alliance Steve Sempier, Mobile Bay National Estuary Program Science Advisory Committee Randy Shaneyfelt, Alabama Department of Environmental Management Lynn Sisk, Alabama Department of Environmental Management Roberta Swann, Mobile Bay National Estuary Program Keith Tassin, The Nature Conservancy Tim Thibaut, Mobile Bay National Estuary Program Science Advisory Committee Angela Underwood, Alabama Department of Conservation and Natural Resources Byron Webb, Alabama Department of Public Health Jason Wilkins, Alabama Department of Environmental Management John Windley, City of Mobile Anne Wynn, Geological Survey of Alabama i
TABLE OF CONTENTSAcknowledgements
Table Of Contents
List of Tables
List of Figures
1.1 Purpose and Intended Use
1.2 The Healthy Watersheds Program
1.3 Overview of Alabama and Mobile Bay Basin Ecoregions
2 Methods Overview
2.1 Healthy Watersheds Assessment Process
2.2 Geographic Scope
2.3 Conceptual Framework
2.4 Spatial Framework
2.5 Watershed Health Metrics and Data Sources
2.6 Watershed Vulnerability Metrics and Data Sources
2.7 Mobile Bay Connectivity Metrics and Data Sources
2.8 Metric Rank-Normalization
2.9 Multimetric Index Development
3 Results & Discussion
3.1 Watershed Health Index
3.2 Watershed Vulnerability Index
3.3 Mobile Bay Connectivity Index
4 Assumptions & Limitations
5 Next Steps & Applications
Appendix A Alabama Map Atlas
Appendix B Mobile Bay Basin Map Atlas
Appendix C Mobile-Tensaw HUC8 and Mobile Bay HUC8 Map Atlas
Appendix D Metric Modeling
Appendix E Streamflow Alteration Analysis
LIST OF TABLESTable 1. Landscape variables considered for predictive statistical models of stream health.
Table 2. Classification of natural and non-natural NLCD cover types
Table 3.Number of NHDPlus catchments with water quality monitoring data.
Table 4. Original directionality of watershed health and vulnerability metrics.
Rank-normalized metric scores range from 0 to 100 and are directionally aligned so that higher scores correspond to higher watershed health, watershed vulnerability, or hydrologic connectivity to Mobile Bay.......... 25 Table 5. List of component metrics for each sub-index and index calculated for the Assessment.................. 26 Table 6. R-Squared values for the Landscape Condition Sub-Index and the remaining watershed health sub-indices. Values are calculated as the square of Pearson Correlation Coefficients........... 28 iii
LIST OF FIGURESFigure 1. Level III ecoregions of Alabama and the Mobile Bay Basin.
Figure 2. Roadmap for the Alabama & Mobile Bay Basin Integrated Assessment of Watershed Health.
......... 8 Figure 3. Illustration of the geographic tiers of the Assessment. Watershed Health and Vulnerability are assessed for Alabama (the Statewide tier) and for the Mobile Bay Basin (the Basin tier).
An analysis of hydrologic connectivity to Mobile Bay is conducted at the Basin tier and within the Mobile-Tensaw and Mobile Bay HUC8s (the HUC8 tier).
Figure 4. Six attributes of watershed health described in Identifying and Protecting Healthy Watersheds Concepts, Assessments, and Management Approaches (US EPA, 2012).
Figure 5. NHDPlus catchments of Alabama and the Mobile Bay Basin.
A detailed view of catchments in the vicinity of Mobile Bay is shown in the inset.
Figure 6. Difference between incremental and cumulative scales for quantifying landscape variables.
Variables quantified at the incremental scale summarize conditions within catchment boundaries only. Variables quantified at the cumulative scale also summarize conditions throughout all upstream catchments.
Figure 7. Watershed health metrics.
Metrics marked with an asterisk (*) are quantified from predictive statistical models. The remaining metrics are quantified from pre-existing geospatial data.
Figure 8. Watershed vulnerability metrics
Figure 9. Mobile Bay connectivity metrics.
Figure 10. Example Histograms for raw (left) and rank-normalized (right) data.
Note that ranknormalization standardizes both the scale and distribution of component metric data................... 24 Figure 11. Watershed Health Index and Sub-Index scores for Alabama catchments
Figure 12. Watershed Health Index and Sub-Index scores for Mobile Bay Basin catchments.
Figure 13. Watershed Vulnerability Index and Sub-Index scores for Alabama catchments.
Figure 14. Watershed Vulnerability Index and Sub-Index scores for Mobile Bay Basin catchments.
.............. 34 Figure 15. Mobile Bay Connectivity Index scores for Mobile Bay Basin catchments.
Figure 16. Mobile Bay Connectivity Index scores for catchments in the Mobile Bay HUC8 and MobileTensaw HUC8.
Figure 17. Map and bar plot of Strahler stream order (Strahler, 1957) for NHDPlus catchments in the Mobile Bay Basin.
Figure 18. Watershed Health Index scores for headwater catchments (stream order 1 or 2) with high Mobile Bay Connectivity (Connectivity Index 75).
EXECUTIVE SUMMARYHealthy waters are a vital part of Alabama’s identity and economy. The state’s high-quality streams, lakes, and wetlands provide a wealth of recreational opportunities, clean drinking water, and other ecosystem services to residents and visitors alike. Their continued function and status as healthy aquatic ecosystems depends in large part on the implementation of protection measures to prevent direct impacts and to maintain key watershed features and processes. A more concerted effort to protect high-quality waters by state agencies and other organizations can support the effectiveness of current efforts to restore impaired waters and circumvent the need for costly restoration in the future.
The purpose of the Alabama and Mobile Bay Basin Integrated Assessment of Watershed Health (the Assessment) is to identify healthy watersheds and characterize relative watershed health across the state and Basin to guide future protection initiatives. A healthy watershed has the structure and function in place to
support healthy aquatic ecosystems. It is characterized as having all or most of these key components:
Intact and functioning headwaters, wetlands, floodplains, riparian corridors, biotic refugia, instream habitat, lake habitat, and biotic communities;
Natural vegetation in the landscape; and Hydrology, sediment transport, fluvial geomorphology, and disturbance regimes expected for its location.
The goals of the Assessment were to:
1. Integrate multi-disciplinary data to both identify healthy watersheds and characterize the relative health of watersheds across the Alabama and the Mobile Bay Basin;
2. Make watershed health data and information readily available to a variety of state, federal, and local programs for watershed protection planning; and
3. Encourage inter-agency partnerships and collaboration to build upon previous efforts to assess watershed health and protect healthy watersheds.
This report presents the methods and results of the planning and analysis phases of the Assessment, and outlines proposed next steps and applications. The Assessment applies a systems approach that views watersheds and their aquatic ecosystems as dynamic and interconnected systems in the landscape connected by surface and ground water and natural vegetative corridors. Watershed health is quantified across the state at the catchment (or subwatershed) scale from existing statewide geospatial datasets and from predictive models derived from field monitoring data collected as part of existing statewide assessment programs. This information is synthesized into several indices that describe watershed health and vulnerability to future degradation.
An important facet of the Assessment is that it leverages existing efforts that have been undertaken to analyze the characteristics of watersheds and the aquatic ecosystems within them. Several agencies and organizations assess various aspects of watershed health at statewide and national scales and/or generate data or tools that facilitate watershed health assessment. This project has forged partnerships among these groups to gather and standardize disparate datasets and provide a more complete picture of watershed health across Alabama and the Mobile Bay Basin.
One outcome of the Assessment is a watershed health database that will be made available to groups involved in watershed protection and restoration planning. The database is intended to help identify healthy watersheds that are priorities for local-scale assessment of protection opportunities. Several immediate uses of the database have been identified by project partners.
A second, more enduring, outcome is the integrated assessment framework developed by project partners.
This framework reflects our understanding of the interconnected nature of the physical, chemical, and biological condition of aquatic ecosystems; the significance of landscape and watershed scale processes on aquatic ecosystem health; and the need to view water bodies as connected parts within a larger system rather than as isolated units. At present, the framework serves as a starting point for agencies and organizations tasked with protecting healthy waters to collaborate and apply a unified approach rather than undertake disjointed efforts. Over the long term, the project partners envision that the existing framework will be updated as data gaps are filled and improved methodologies are identified.