WARM MINERAL SPRINGS FOCAL AREA CONCEPTUAL DESIGN FOR FRESHWATER RESTORATION Final Report 5 November 2012 Steven J. Herrington, Ph.D. Director of Freshwater Conservation The Nature Conservancy, Florida Chapter FWC Agreement Number: 11043 1 ABSTRACT The Warm Mineral Springs Focal Area is considered the most important winter refuge site for the Florida manatee (Trichechus manatus latirostris) in the southern portion of its range in the Gulf of Mexico in Florida. However, natural resource managers are concerned that historical and current alterations of Warm Mineral Springs, Warm Mineral Springs Creek, and Salt Creek may reduce access and degrade habitat quality for Florida manatees in the system. The objectives of this study were to conduct a watershed assessment for river stability and sediment supply and develop conceptual designs for restoring the ecological condition, fluvial geomorphology, and habitat quality and accessibility for Florida manatees in the Warm Mineral Springs Focal Area. Historical and current land use alteration and management, bank erosion and excessive sedimentation, and invasive riparian plant species were identified as the primary factors degrading the focal area. Five project areas were defined for restoration, including Project 1: Bank Stabilization of the Warm Mineral Springs Pool at the Warm Mineral Springs Resort and Day Spa; Project 2: Bank Stabilization and Channel Restoration of Warm Mineral Springs Creek at the Warm Mineral Springs Resort and Day Spa; Project 3: Stream Channel Restoration of Warm Mineral Springs Creek; Project 4: Riparian Corridor Restoration for Optimizing Manatee Winter Refuge Habitat in Warm Mineral Springs Creek; and Project 5: Stream Channel Restoration of Salt Creek. Restoration can be implemented at these sites either independently or concomitantly. Removal and control of invasive Brazilian pepper (Schinus terebinthifolius) in the riparian zone as well as its branches, limbs, and debris from the channel in the Project 4 areas can provide immediate restoration and enhancement as well as increase the total area of Florida manatee winter aggregation habitat and should be considered a top priority for restoration. Excessive sedimentation in project areas 2 and 3 pose a threat to the habitat quality of the downstream winter aggregation habitats in Project Area 4 and should be removed from creek channel. Spring and creek banks in project areas 1 and 2 should be stabilized and revegetated with native deep-rooting overstory, understory, and ground cover plants to reduce current sedimentation Warm Mineral Springs and Warm Mineral Springs Creek. Stream channel restoration using natural channel design techniques should be further assessed in the Project 5 area for providing reliable, consistent, self-maintaining, long-term habitat accessibility as well as increased winter aggregation habitat area for Florida manatees throughout the Warm Mineral Springs Focal Area. 2 ACKNOWLEDGMENTS I would like to especially thank Cameron Morris for field assistance. I would like to thank Nicole Adimey, Carol Knox, Chris Metcalf, Ron Mezich, Dave Rosgen, Kent Smith, Cliff Harris, and Mike Elswick for field assistance and data analysis and interpretation. I would like thank Sarasota County, the City of North Port, FL, and the Warm Mineral Springs Day-Spa and Resort staff for providing access to the site and general accommodations. This project was funded by Florida Fish and Wildlife Conservation Commission’s program, Florida’s Wildlife Legacy Initiative, and the U.S. Fish and Wildlife Service’s State Wildlife Grants program (FWC agreement number 11042). 3 TABLE OF CONTENTS INTRODUCTION ........................................................................................................................................ 6 PROJECT GOALS AND OBJECTIVES ..................................................................................................... 6 METHODS ................................................................................................................................................... 7 EXISTING CONDITIONS ........................................................................................................................... 8 HISTORICAL STREAM ALTERATION AND RELEVANCE TO THE FLORIDA MANATEE ......... 15 PROBLEM IDENTIFICATION: WARM MINERAL SPRINGS FOCAL AREA ................................... 26 PROJECT SITE IDENTIFICATION ......................................................................................................... 27 Project 1: Bank Stabilization of the Warm Mineral Springs Pool at the Warm Mineral Springs Resort and Day Spa ....................................................................................................................................................... 29 Restoration Objectives ................................................................................................................... 29 Description ..................................................................................................................................... 29 Condition ....................................................................................................................................... 31 Problem Identification ................................................................................................................... 31 General Restoration Recommendations......................................................................................... 36 Restoration Design Approach ........................................................................................................ 37 Preliminary Design and Construction Cost Estimate .................................................................... 38 Project 2: Bank Stabilization and Channel Restoration of Warm Mineral Springs Creek at the Warm Mineral Springs Resort and Day Spa .......................................................................................................... 41 Restoration Objectives ................................................................................................................... 41 Description ..................................................................................................................................... 41 Condition ....................................................................................................................................... 43 Problem Identification ................................................................................................................... 53 General Restoration Recommendations......................................................................................... 53 Restoration Design Approach ........................................................................................................ 55 Preliminary Design and Construction Cost Estimate .................................................................... 56 Project 3: Stream Channel Restoration of Warm Mineral Springs Creek ................................................... 57 Restoration Objectives ................................................................................................................... 57 Description ..................................................................................................................................... 57 Condition ....................................................................................................................................... 57 Problem Identification ................................................................................................................... 69 General Restoration Recommendations......................................................................................... 69 Restoration Design Approach ........................................................................................................ 70 Preliminary Design and Construction Cost Estimate .................................................................... 71 Project 4: Riparian Corridor Restoration for Optimizing Manatee Winter Refuge Habitat in Warm Mineral Springs Creek ............................................................................................................................... 72 Restoration Objectives ................................................................................................................... 72 Description ..................................................................................................................................... 72 Condition ....................................................................................................................................... 74 Problem Identification ................................................................................................................... 75 General Restoration Recommendations......................................................................................... 75 Restoration Design Approach ........................................................................................................ 78 Preliminary Design and Construction Cost Estimate .................................................................... 78 Project 5: Stream Channel Restoration of Salt Creek ................................................................................. 79 Restoration Objectives ................................................................................................................... 79 Description