Issue papers: Mitigation

Issue papers

The Southwest Florida Water Management District manages water resources to balance the needs of current and future water users while also protecting the environment. The District’s authority to regulate water-related activities is a major tool in accomplishing this mission.

The District issues water use permits for water withdrawals. A water use permit is permission given to an applicant to use the public’s water resource in a specified way, for a specified period of time, under certain restrictions and considerations. The District also issues environmental resource permits for activities affecting stormwater, water quality, floodplain management and wetlands.

A permitted activity may sometimes impact wetlands or floodplains. A wetland is an area that is saturated by surface or ground water for a sufficient period of time to support plants that are adapted to life in flooded or wet soils. A floodplain is relatively low land that is likely to be inundated following a storm.

When a permitted activity adversely impacts the environment, an action or series of actions that offset the environmental impact is required. This is called mitigation. There are two types of impacts routinely offset by mitigation: wetland impacts and floodplain impacts.

Wetland mitigation offsets the loss of the benefits and functions of wetlands by providing an equivalent increase in benefits and functions in another area. Wetlands are critical to the health of the environment. They protect water quality by filtering sediments, nutrients and other material from runoff before it enters water bodies. Wetlands are a natural water storage system and act as floodwater detention areas. Important wildlife, recreational game, commercial and recreational fish, and many protected species live in wetlands.

When a permitted activity causes adverse environmental impacts, a permit applicant must try to modify the plan to reduce or eliminate those impacts. This is done by modifying the design of the project where possible. When design modifications have been completed, adverse impacts that remain may be offset by: creating new wetlands; restoring or enhancing impacted wetlands; preserving wetlands; preserving uplands; or various combinations of the above.

The amount of impacted wetland versus the amount that must be created, restored, enhanced or preserved is determined by the Uniform Mitigation Assessment Method (Chapter 62-345, Florida Administrative Code.) This rule provides a standardized procedure for assessing the functions provided by wetlands so that the functional loss caused by a proposed impact and the relative functional gain resulting from the proposed mitigation can be determined. When the functional gain provided by mitigation equals or exceeds the function loss resulting from wetland impacts, the wetland impact is considered to be offset.

When mitigation is allowed, there are four types that can be used:

Creation: The creation of new wetlands typically involves digging a basin and planting trees or leafy plants to create a new wetland area.
Restoration: If a wetland has been affected so that it no longer functions as a wetland, it can be restored to its original condition. This is generally expected to be more successful than wetland creation because the area once served as a wetland. Soil characteristics, water levels, elevations and other factors favor wetland restoration.
Enhancement: In this type of mitigation, the environmental value of a previously damaged wetland is improved. This is often done by removing exotic plant species that pose a threat to Florida’s natural systems by destroying wetland habitats, reducing wildlife food sources, and altering fire and drainage patterns.
Preservation: This type of mitigation offers improved protection of important ecosystems. Preservation can include land donations and conservation easements that prohibit activities harmful to the resource, or other comparable land-use restrictions of wetlands, other surface waters or uplands. Preservation will most frequently be used in combination with one of the other three types of mitigation.

In general, wetland mitigation is best when it is at the impacted area or close to the impacted area. Off-site mitigation is allowed when it offsets adverse impacts and on-site mitigation isn’t beneficial, or if it would improve the ecological value of the area. When off-site mitigation is allowed, permit applicants can use a mitigation bank.

A mitigation bank has a permit to improve the conditions of an area through creation, restoration, enhancement or preservation. In exchange for improving these conditions, the mitigation bank earns mitigation credits. Applicants for permits that allow off-site mitigation can purchase credits from the bank to fulfill mitigation requirements.

A credit is a standard unit of measure that represents the increase in ecological value resulting from restoration, enhancement, preservation, or creation activities. For the permit applicant, the benefits of using a mitigation bank include cost savings and transfer of responsibility for monitoring and maintaining the mitigation area. For the public, the benefits include increasing the chances of success by consolidating multiple projects into larger areas.

A mitigation area is monitored until its success can be demonstrated. This means all applicable water quality standards are met, it has demonstrated sustainable ecological and hydrological functions, and specific conditions in the permit are met.

The second, and most common, type of mitigation is floodplain mitigation.

For this type of mitigation, the District most commonly uses a “cup for cup” theory. For instance, during development, when part of a basin is filled, another part of the same basin must be emptied. Or, if you fill a cup, you must empty a cup.

Whether addressing impacts to wetlands or floodplains, mitigation is one of the tools used by the District to fulfill its mission of protecting the water resources.

May 2005