Prepared in cooperation with the Coastal Protection and Restoration Authority (CPRA) of Louisiana Performance Measures for a Mississippi River Reintroduction Into the Forested Wetlands of Maurepas Swamp Scientific Investigations Report 2017–5036 U.S. Department of the Interior U.S. Geological Survey Cover. Coastal swamp forest in Louisiana undergoing a transition between a closed canopy and open canopy habitat, representing the primary habitat targeted for a Mississippi River reintroduction into Maurepas Swamp, Louisiana (photograph by Ken W. Krauss, U.S. Geological Survey). Performance Measures for a Mississippi River Reintroduction Into the Forested Wetlands of Maurepas Swamp By Ken W. Krauss, Gary P. Shaffer, Richard F. Keim, Jim L. Chambers, William B. Wood, and Stephen B. Hartley Prepared in cooperation with the Coastal Protection and Restoration Authority (CPRA) of Louisiana Scientific Investigations Report 2017–5036 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior RYAN K. ZINKE, Secretary U.S. Geological Survey William H. Werkheiser, Acting Director U.S. Geological Survey, Reston, Virginia: 2017 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://store.usgs.gov. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Krauss, K.W., Shaffer, G.P., Keim, R.F., Chambers, J.L., Wood, W.B., and Hartley, S.B., 2017, Performance measures for a Mississippi River reintroduction into the forested wetlands of Maurepas Swamp: U.S. Geological Survey Scientific Investigations Report 2017–5036, 56 p., https://doi.org/10.3133/sir20175036. ISSN 2328-0328 (online) iii Acknowledgments The development of these performance measures was supported by the Coastal Protection and Restoration Authority (CPRA) of Louisiana. Specifically, we thank Carol Parsons Richards, Honora Buras, Brad Miller, and Richard Raynie, all with CPRA, for tasking this effort and providing much needed feedback along the way. Along with these partners, additional reviews of this document were provided by Danielle Richardi (CPRA), Christopher M. Swarzenski (U.S. Geological Survey [USGS]), William H. Conner (Clemson University), Robert R. Lane (Louisiana State University), Steve Smith (Louisiana Department of Wildlife and Fisheries), and Beth A. Middleton (USGS). Supplemental funding for the development and publication of these performance measures was provided by the USGS Climate Research & Development Program, USGS Environments Program, and USGS Wetland and Aquatic Research Center. iv Contents Acknowledgments ........................................................................................................................................iii Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................2 Wetland Restoration ......................................................................................................................................2 Mississippi River Reintroduction Into Maurepas Swamp ......................................................................3 Targeted Wetland Habitats of Maurepas Swamp ...................................................................................3 Performance Measures and Adaptive Management ..............................................................................5 PM1: Establishing a Hydrologic Regime Consistent With Swamp Forest Sustainability ..........8 Performance Measure Discussion and Literature .................................................................8 Hydrology Performance Measure ............................................................................................9 Considerations..............................................................................................................................9 Assessment Methods .................................................................................................................9 Water Balance ...................................................................................................................9 Flooding and Drought .......................................................................................................11 Sediment Deposition and Scour .....................................................................................11 Hydrologic Connectivity ...................................................................................................11 PM2: Ameliorating Salinity Intrusion ..............................................................................................12 Performance Measure Discussion and Literature .............................................. 12 Salinity Performance Measure ...............................................................................................14 Considerations............................................................................................................................14 Assessment Methods ...............................................................................................................14 PM3: Increasing Rates of Soil Surface Elevation Gain ...............................................................16 Performance Measure Discussion and Literature ..............................................................17 Soil Surface Elevation Performance Measure .....................................................................18 Considerations............................................................................................................................19 Assessment Methods ...............................................................................................................20 Radioisotope Dating of Cores .........................................................................................21 Rod SETs .............................................................................................................................21 Repetitive Surveying of SETs by Using High-Precision d/RTK-GPS and cGPS ......22 PM4: Increasing Forest Structural Integrity ...................................................................................22 Performance Measure Discussion and Literature ...............................................................22 Forest Structural Integrity Performance Measures ............................................................23 Stand Density ....................................................................................................................23 FFQI......................................................................................................................................24 Considerations ...........................................................................................................................24 Stand Density ....................................................................................................................24 FFQI......................................................................................................................................24 Assessment Methods ...............................................................................................................26 PM5: Facilitating Nutrient Uptake and Retention ..........................................................................26 v Performance Measure Discussion and Literature ...............................................................27 Nutrient Uptake and Retention Performance Measure ......................................................27 Considerations............................................................................................................................28 Assessment Methods ...............................................................................................................29 Water Quality Analysis .....................................................................................................29 Analysis of Deposited Sediments ..................................................................................29 Reference Sites ............................................................................................................................................30 Conclusions...................................................................................................................................................30 References Cited .........................................................................................................................................34 Appendix 1. Current Plot and Data Availability of Potential Relevance for Future Monitoring ...........................................................................................................................43 Figures 1. Map showing location and certain