With a Comprehensive Management Plan completed for the Three Mile Creek Watershed completed in September 2014, partners are making progress towards implementing recommended measures to address the primary problems impacting Mobile’s historic waterway. These problems include:
- Excessive water quality pollutants, including trash and organic debris; nutrients from fertilizer, pet waste, waste treatment output; and pathogens/bacteria from old decaying infrastructure and sanitary sewer overflows.
- Illicit connections between sanitary sewer pipes and stormwater draining systems that provide a source of pollutants into stormwater outfalls and groundwater entering TMC.
- Effects of stormwater runoff discharging from the streets, parking lots, and rooftops of the developed watershed, including delivery of trash and litter, sediment, organic matter, fertilizer, pet waste, metals, and petrochemicals and streambank erosion/sedimentation from increased velocity and volume of stormwater.
- Altered watershed hydrology resulting from 1980s TMC flood control efforts, including channelization, berms eliminating connections to the floodplain, and construction of energy dissipating weirs that block tidal influence.
- Altered creek geomorphology, including concrete, riprap, and gabion linings that eliminate habitat, block infiltration, and eliminate riparian buffers that provide nesting areas for birds and roots that stabilize stream banks and provide structure for fish.
- Submerged aquatic vegetation of largely exotic, nuisance species, slowing water flow, impeding recreational usage and contributing to low dissolved oxygen concentrations.
- Potential groundwater contamination from the Hickory Street Landfill and the Mobile Gas Restoration Site of the former coal gasification facility
- Abundance of invasive species, including the Island Apple Snails, aforementioned SAV, and other invasive plant species like Chinese tallow/popcorn trees, Chinese privet, taro/elephant ears, alligator weed and others.
WMP Implementation. With five Primary Goals, improving water quality, providing access to resources, protecting and improving fish and wildlife health, restoring the heritage and cultural connection between the watershed and community, and planning preparing for climate resiliency, identified projects having the greatest potential to provide early benefits. Grouped under the challenges facing TMC, these are the first WMP-recommended projects being undertaken:
Access. Recommendation: Build Greenways. The City of Mobile secured a $386K National Park Service Outdoor Legacy Program Grant to design and construct the first segment of a TMC bicycle/walking trail along TMC from MLK Jr. Ave to Tricentennial Park. Design includes lighting, an exercise/circuit course, and green infrastructure/stormwater management features. The Mobile County Health Department has secured additional funding from the Sybil Smith Trust to extend the trail to Fillingim Street and install a kayak launch at Tricentennial Park.
Stormwater. Recommendations: Remove sediment (Langan Park), Construct energy dissipater on Twelve Mile Creek, and Install green infrastructure retrofits in public areas. The City of Mobile has secured a Natural Resource Conservation Service Emergency Watershed Protection Grant to address erosion and sedimentation upstream of the Langan Park lakes. An MBNEP proposal to restore a different segment of Twelve Mile Creek was approved for funding by the RESTORE Council in December, and funding is expected to be made available later in 2016. Restoration measures are expected to include green infrastructure measures to reduce energy and volume of stormwater runoff. Twelve Mile Creek drains a highly impervious watershed, is particularly flashy, and is considered to provide the most significant source of sediment to the lakes.
Ecology. Recommendation: Improve management of invasive species. An MBNEP proposal to develop an invasive species control plan for the TMC Watershed was approved for funding by the RESTORE Council in December, and funding is expected to be made available later in 2016. MBNEP is developing a proposal to fund creation of an urban Conservation Corps comprising at-risk young adults from the lower TMC watershed for a year of employment implementing measures recommended in that plan, giving them job skills that contribute to the sustainability of our coastal assets and lead to future employment opportunities in a restoration economy.
Sea Level Rise. Recommendation: Incorporate flood risk management and storm surge information in educational outreach program. Auburn University has delineated watershed boundaries for Toulmins Spring Branch (TSB) and calibrated a stormwater management model (SWMM) to guide stormwater management actions in this low-lying, climate vulnerable subwatershed. MBNEP conducted an outreach program to 1) engage residents of the TSB to increase community understanding about watershed dynamics, climate change, and sea level rise, 2) assess present concerns and future fears related to climate change in this community, and 3) plan for adaptation to mitigating those concerns and fears. MBNEP supported the development of the MLK Avenue Redevelopment Corporation Leadership Academy to engage residents of Mobile’s Bottom area to provide leadership in community adaptation to environmental pressures related to climate changes.
Monitoring and Research Studies
- Prichard Drainage Study: Toulmins Spring Branch and Gum Tree Branch
- Three Mile Creek Data Collected
- Three Mile Creek Impaired Waterbodies (303d List)
- Three Mile Creek Total Maximum Daily Loads (TMDL)
- Three Mile Creek Stormwater Outfall Inventory
- Impervious Surface Study 2004
- Toulmins Spring Branch Stormwater Management Study - Maharam Dukua : Maharam Dakua served in Mobile, Alabama as part of the U.S. State Department’s Community Solutions Program. For the past four-months, Maharam joined an Auburn University team hired by MBNEP to work in the Toulminville area of the Three-Mile Creek Watershed. This project aimed at developing a model to help Mobile County and city planners make science based decisions related to capital improvement budgets for infrastructure maintenance. His primary role was to learn about community concerns related to flooding and water pollution by engaging the residents in learning about best practices for managing and reducing water volumes and other sources of pollution. Maharam created a presentation to reflect his work within the Toulmins Spring Branch of the Three Mile Creek Watershed.