Project Types

We considered four primary project types for the GEMS project: habitat restoration, restoring hydrological connectivity, recreational enhancements, and water quality infrastructure improvements. These projects vary greatly in the process and materials used, environmental conditions required, social and legal contexts, and expected outcomes (economic, health, recreation, harvest, shoreline protection, recreation etc.). Summaries of the project types included in the GEMS project are provided below. To see more detail about each project type, including key outcomes and ecosystem service logic models, click the names of individual project types below or search the ESLM database.

ESLM Project Types

Project Type: Habitat Restoration

Salt Marsh Restoration

Project type: Habitat Restoration

Salt marsh restoration techniques in the Gulf of Mexico consist of constructing dikes to isolate an area and pumping in sediment, planting new native vegetation, or creating river diversions. River diversions, where water from rivers is diverted to flow through marsh areas, are most often used in Louisiana but have also been used in Texas and are normally considered a long-term restoration. These interventions typically create conditions for native salt marsh vegetation to reestablish. Planting new vegetation kick starts this process and provides a layer of redundancy when paired with one of the other restoration actions.

Seagrass Restoration

Project type: Habitat Restoration

Seagrass restoration projects in the Gulf of Mexico include transplanting seagrass into restoration sites (very common), seeding seagrass (less common, newer technique), and modifying sediment to facilitate seagrass growth (usually used in combination with transplanting or seeding). Many seagrass restoration projects in the Gulf of Mexico, especially in Florida, are done to mitigate seagrass loss due to development, as required by the Clean Water Act. Some projects attempt to benefit seagrass by addressing water quality issues.

Mangrove Restoration

Project type: Habitat Restoration

Specific techniques for mangrove restoration vary in terms of the process used, but primarily consist of restoring site conditions to those that are conducive to mangrove growth and waiting for mangrove propagules to colonize the site. These restoration activities include hydrological restoration (to restore proper tidal flow, freshwater inputs, and salinity levels) and restoring sediment elevation. In some areas of the Gulf mangrove site creation, rather than restoration, is being performed (i.e., creating site conditions conducive to mangrove recruitment in an area where mangroves didn’t exist before). Restoration in this region very rarely involves planting seedlings.

Living Shorelines

Project type: Habitat Restoration

Living shorelines are combinations of vegetation planted along a shoreline and a structure to help hold the vegetation in place. They are primarily installed to protect shorelines from erosion as an alternative to hardened infrastructure like bulkheads or riprap. In the Gulf of Mexico, the structural component of the living shoreline is usually a breakwater and can be made of a variety of materials, including bagged oyster shell, granite, eco-concrete, and reef balls or blocks. Living shorelines can be implemented at small scales by individual property owners or as larger projects that are hundreds of meters to a kilometer long. Larger living shoreline projects are often aimed at protecting marsh or coastal infrastructure.

Beach and Dune Restoration

Project type: Habitat Restoration

Beach restoration in the Gulf of Mexico aims to replace sand that erodes from a beach. It is usually completed by dredging offshore sand and adding it onto the beach. Finding a similar grain size to the sand that is already in the beach/dune system is the most important consideration when adding sand dredged from offshore because the wrong sized sand grains can be easily re-dispersed due to wave action specific to an area. Beach restoration, beach replenishment, beach nourishment, and beach renourishment are all terms used to refer to this action.

Dune restoration also aims to offset sand erosion but may also include increasing dune size and resilience. There are three major types of dune stabilization techniques: importing dredged sand from offshore to build up the dune, planting grasses or other plants to secure the sand, and installing fencing along the dune on both the seaward and landward sides of the dune. Planting and fencing projects are often referred to as dune stabilization practices, but all three techniques fall under the umbrella of dune restoration. Planting and fencing projects are often less expensive than building up the dune. The most successful restoration projects use all three techniques to add redundancy.

Restoring Hydrologic Connectivity

Project type: Habitat Restoration

As defined by the RESTORE Council, restoring hydrologic connectivity means “restoring or mimicking natural connections that have been broken or disrupted by infrastructure such as roads and levees.” This often involves removing barriers to flow (e.g., old flood control structures) or installing structures like culverts to enable water to flow under or around an existing barrier.

Project Type: Oyster Reef Restoration

General Oyster Reef Restoration

Project type: Oyster Reef Restoration

Structurally Simple, Subtidal, Intensively Harvested Oyster Reef Restoration

Project type: Oyster Reef Restoration

This technique consists of placing cultch material (usually oyster shells, relic shells, crushed limestone, or crushed concrete), either loose or contained, so that the resulting structure lies flat along the estuary/ocean floor. This technique has been widely used throughout the Gulf for the primary purpose of providing oysters for harvest.

Structurally Complex, Subtidal, Intensively Harvested Oyster Reef Restoration

Project type: Oyster Reef Restoration

Large, durable structures (e.g. oyster balls, precast concrete structures, and limestone structures) are placed in subtidal areas to create substrate to which oysters can attach. The resulting oyster reef has a significant vertical component, provides a more complex structure which oysters (of varying ages) and other aquatic organisms can use for habitat, and is less likely to be buried by sediment or degraded by waves than the simpler structures in the previous technique.

Structurally Complex, Subtidal, Not Intensively Harvested Oyster Reef Restoration

Project type: Oyster Reef Restoration

This technique is identical to Structurally Complex, Subtidal, Intensively Harvested Oyster Reef Restoration, except that intensive harvesting (dredging or intensive tonging) is not permitted.

Structurally Complex, Intertidal, Not Intensively Harvested Oyster Reef Restoration

Project type: Oyster Reef Restoration

Large, durable structures (e.g. oyster balls, precast concrete structures, rocks, limestone structures) are placed in intertidal areas to create substrate to which oysters can attach. Projects using this technique are often called “living shoreline” projects, as they are intended to protect shorelines from erosion by stabilizing sediment and attenuating waves as they approach the shoreline.

Protection or Enhancement of Existing Oyster Reef

Project type: Oyster Reef Restoration

These projects focus on the protection of an existing oyster reef from intensive harvest (dredging), with or without reef enhancement (via seeding or placing oysters in existing reef area). Protected reefs could still allow low-impact harvesting methods (tonging or hand collection) that do not threaten the reef structure or long-term viability of the oyster populations. The objective of these projects is to support a sustainable oyster population, allow the reef to develop structurally over a long period, and possibly to create a source of oyster larvae to nearby reefs.

Oyster Aquaculture

Project type: Oyster Reef Restoration

Oyster aquaculture projects of varying methods, including all bottom and off-bottom techniques. These projects encompass both intertidal and subtidal projects, and are considered to be intensively harvested, since the primary goal of oyster farming is harvest and consumption.

Project Type: Recreational Enhancement

Boat Ramps

Project type: Recreational Enhancement

Typically boat ramp projects entail either repairing existing boat ramps or constructing new boat ramps. These projects are meant to increase access to public waterways, offshore areas, and inaccessible campgrounds. Ramp construction or repair often involves removing sediment and water to put in place the underwater part of the ramp and then attaching concrete slabs. 

Fishing Piers

Project type: Recreational Enhancement

Fishing piers are installed to improve access to coastal waterfront areas, generally beaches. Fishing piers can increase access to fishing and wildlife viewing. There are several different ways to construct, restore, or enhance the central body of the pier however, central to all pier construction is the installation of load-bearing piles in the benthos to anchor the main body of the pier. Successful projects improve accessibility to the waterfront, facilitating increased coastal- based anthropogenic activity in the areas around the pier. Pier projects are popular across all Gulf states and are particularly frequent throughout Florida.

Trails and Boardwalks

Project type: Recreational Enhancement

Specific techniques for trail and boardwalk projects vary in installation processes and materials used and are generally site specific. More broadly, trails and boardwalks aim to increase accessibility to waterfront areas for a range of activities including walking, hiking, biking, horseback riding, and fishing. Whereas trails are generally installed on raised ground, or ground that does not easily become submerged by water and can therefore provide consistent accessibility, boardwalk installation is required for access over wet or marshy areas or areas associated with sensitive wildlife and vegetation. Boardwalks therefore consist of raised platforms, requiring the installation of footings into the substrate. The materials used to make boardwalks can vary based on substrate composition and other adjacent environmental factors, including sunlight, moisture, and sediment composition. Trail and boardwalks networks are common throughout recreational areas of the Gulf Coast.

Project Type: Water Quality Improvement

Wastewater Management – Sewage System Improvements

Project type: Water Quality Improvement

Sewage system improvements include two specific techniques: converting basic septic systems to either centralized sewer systems or advanced septic systems, and repairing existing sewage system components.  The transition from decentralized, basic septic systems to a centralized sewer system as a method for wastewater treatment is usually done in a spatially defined area; new sewer lines are installed to serve the area, and individual properties are connected to the sewer lines and their existing septic tanks decommissioned.  An alternative to septic to sewer conversion is replacing basic septic systems, consisting of a septic tank and soil treatment system, with advanced septic systems that use aerobic treatment or filters to reduce nutrient, pathogen, and total suspended solids in the effluent.  

Repairing leaks or other defects in existing sewage system components is necessary to prevent untreated sewage from moving into surface and groundwater.

Wastewater Management – Wastewater Treatment Plant Upgrades

Project type: Water Quality Improvement

Wastewater treatment plants are offsite, centralized systems meant to remove toxins, pathogens, organic material, and more from sewage and wastewater coming from residential, industrial, and municipal environments.

The remaining water after this treatment process is known as grey water and could potentially be used for services such as crop irrigation and industrial cooling processes. Greywater reuse can increase water productivity and reduce freshwater demand in places where freshwater is not an unlimited resource (which is most places.) To date, there does not appear to be wide-scale implementation of wastewater treatment plants harnessing and supplying municipalities with gray water for reuse.

Wastewater Management – Treatment Wetlands

Project type: Water Quality Improvement

Treatment wetlands for wastewater treatment are engineered systems designed to replicate the structure and the services often provided by wetlands in order to perform tertiary wastewater treatment, particularly phosphorus and waterborne pathogen removal, and nitrogen transformation and removal through a variety of physical, chemical, and biological mechanisms. Treatment wetlands (sometimes known as constructed wetlands) are often used to support traditional municipal and industrial wastewater treatment but can also be used for stormwater, aquaculture, and mine drainage. There are two types of treatment wetlands: free water surface (FWS) wetlands and subsurface flow (SSF) wetlands. FWS wetlands generally look like marshes and consist of multiple species of rooted emergent vegetation and standing water. FWS systems that utilize only submerged or floating vegetation are comparatively less common. Subsurface Flow Systems (SSF), on the other hand, maintain water flow below the surface.

Stormwater Management – Gray Infrastructure

Project type: Water Quality Improvement

Grey infrastructure for stormwater management refers to a network of water retention and purification infrastructure (such as pipes, ditches, swales, culverts, and retention ponds) meant to slow the flow of stormwater during rain events to prevent flooding and reduce the amount of pollutants entering waterways.

Restoration projects for grey infrastructure typically do not focus on the entire stormwater management system, but rather on enhancing, repairing, removing, or installing new infrastructure in ways that will optimize the efficiency of the system and reduce the likeliness of flooding or polluting waterways during and after storm events. As such, restoration projects can focus on the repair or maintenance of, addition, or removal of ditches, weirs, culverts, storm drains, and stormwater retention ponds/basins. These interventions can also restore hydrological pathways.

Stormwater Management – Green Infrastructure

Project type: Water Quality Improvement

Green infrastructure for stormwater management includes a variety of methods designed to slow or retain precipitation where it falls, rather than collecting precipitation and directing it to a centralized pond or treatment system.  Green infrastructure for stormwater management includes bioswales, rain gardens, permeable pavements, green roofs, and engineered wetlands; there is currently a lack of consistent terminology and definitions among green infrastructure practitioners and researchers.

Stormwater Management – Outflow Treatment (Baffle Boxes)

Project type: Water Quality Improvement

Baffle boxes are infrastructure components typically found near the end of the stormwater management system, positioned at outfalls or in types of stormwater management infrastructure. Baffle boxes attach to stormwater outfalls and contain a series of sediment settling chambers separated by baffles. Stormwater runoff enters through the boxes which capture sediment and pollutants in the storage zones. When the first chamber is full, flow is directed to the second chamber, and so on. Larger particles, including marine debris, tend to settle in the first chamber and smaller particles associated with sediment accumulate in the other chambers.

Agriculture Best Management Practices

Project type: Water Quality Improvement