Understanding Wetlands: From Hydric Soils to Compensatory Mitigation
Wetlands are among the most regulated and ecologically valuable landscapes in the United States — yet most people couldn’t define one if asked. Understanding what a wetland actually is, how scientists identify them in the field, and what happens when one is impacted by development is essential knowledge for anyone working in real estate, construction, engineering, or environmental consulting in Florida and beyond.
This blog breaks it all down.
What Is a Wetland?
Most people think a wetland is just a swamp. Legally, that’s not how wetlands are defined.
Under federal guidance, a wetland is identified using three indicators that must all be present:
- Wetland Hydrology — Water is present at or near the surface during the growing season. This can include standing water, saturated soils, or evidence of periodic inundation such as water stains on trees or lichen lines on bark.
- Hydric Soils — Soils that have formed under saturated conditions. These soils develop distinctive color patterns and chemical changes due to prolonged oxygen deprivation.
- Hydrophytic Vegetation — Plants that are adapted to growing in wet environments. These species have evolved to survive in saturated or flooded conditions.
When all three indicators are present, the area is typically considered a wetland under federal and state law — and is subject to regulatory protection.
What Is Hydric Soil?
Of the three wetland indicators, hydric soil is often the most reliable and the most misunderstood.
Hydric soils form when the ground stays saturated with water long enough during the growing season to create anaerobic conditions — meaning the soil becomes waterlogged and oxygen disappears. When oxygen is depleted, important chemical changes occur that leave permanent marks in the soil profile.
What to look for:
- Gray or bluish matrix — A sign that the soil has been chronically deprived of oxygen. This color pattern, known as gleying, develops when iron compounds are chemically reduced under saturated conditions.
- Redox concentrations — Rust-colored spots or streaks that form where iron has moved through the soil during wet and dry cycles. These are one of the most common hydric soil indicators observed in the field.
- Dark organic surface layers — Plant material that accumulates in saturated environments and decomposes slowly due to low oxygen, creating a dark, organic-rich horizon near the soil surface.
When wetland scientists observe these features during a field assessment, it is a strong indicator that the area may meet the criteria for wetland designation.
What Happens When a Wetland Is Impacted?
Wetlands don’t exist in a regulatory vacuum. When a development project impacts a wetland or stream, the Clean Water Act often requires something called compensatory mitigation.
Compensatory mitigation means replacing the aquatic resources that were lost because of a permitted impact. If a developer fills a wetland or alters a stream, they must compensate by restoring, creating, enhancing, or preserving wetlands or streams somewhere else. The overarching goal is called no net loss of aquatic resource functions and values — a national policy established in 1989.
Today, most compensatory mitigation happens through one of two mechanisms:
- Mitigation Banks — Large-scale restoration projects permitted in advance by state and federal agencies. Developers purchase mitigation credits from the bank to offset their impacts.
- In-Lieu Fee Programs — Similar in concept, but payments are made to a government or nonprofit program that pools funds for future restoration projects.
Of the two, mitigation banking is widely considered the more ecologically effective approach. Restoration occurs before impacts take place, credits are based on measurable ecological lift, and long-term conservation easements protect the land in perpetuity.
How Does Mitigation Banking Work?
A mitigation bank is established by restoring degraded land — often former agricultural or timbered land — back to a functioning wetland or stream system. Based on the ecological improvements achieved, state and federal agencies award mitigation credits that the bank sponsor can sell to developers within the same watershed.
The process requires years of permitting, restoration planning, and regulatory approval. Credits are released incrementally as ecological milestones are met, ensuring the restoration is on track before more credits become available for sale.
For a developer, purchasing mitigation credits is the most efficient path to permit compliance. Rather than managing their own restoration project, they transfer that responsibility to a permitted bank — saving time, reducing risk, and providing regulatory certainty from day one.
Why It Matters
Wetlands provide flood protection, water quality filtration, aquifer recharge, and critical habitat for fish and wildlife. When development impacts these systems, compensatory mitigation ensures those functions are not permanently lost.
Understanding the science behind wetland identification — and the regulatory framework that governs impacts — is essential for developers, landowners, and environmental professionals navigating the permitting process in Florida and across the country.
At The Mitigation Banking Group, we work with clients throughout Florida to identify available mitigation credits, navigate service area requirements, and facilitate permit compliance. Contact Victoria Bruce for guidance on your next project.
Videos courtesy of Swamp School. Visit swampschool.org to learn more about wetland science and environmental regulation.
