Environmental Resource Permits (ERP) for Drainage

What Is an Environmental Resource Permit?

An Environmental Resource Permit — commonly called an ERP — is the primary regulatory permit for any project in Florida that affects surface water management. If your drainage project involves constructing or modifying a stormwater management system, altering wetlands, or changing how water flows on your property, you likely need an ERP from one of Florida's five water management districts.

In South Florida, ERPs are issued by the South Florida Water Management District (SFWMD). In other parts of the state, the St. Johns River, Southwest Florida, Northwest Florida, and Suwannee River water management districts handle ERP reviews. The Florida Department of Environmental Protection (FDEP) also issues ERPs for certain projects, particularly those in areas where it serves as the reviewing agency on behalf of the district.

The ERP process can be complex and time-consuming, but it does not have to be painful. Our engineers have guided hundreds of projects through the ERP process since 2004, across Palm Beach, Broward, Miami-Dade, and surrounding counties. This guide explains what an ERP covers, when you need one, how to apply, and what to expect during review.

What the ERP Covers

The ERP is a comprehensive permit that addresses multiple aspects of surface water management. Unlike a simple building permit that focuses on construction standards, the ERP evaluates your project's impact on the entire water system — quantity, quality, and environmental resources.

Stormwater Quantity

The ERP requires that your project does not increase stormwater runoff to downstream properties or infrastructure. In practical terms, this means:

Pre- vs. post-development analysis: You must demonstrate that the peak discharge rate from your site after development does not exceed the rate before development, typically for the 25-year, 72-hour design storm.
On-site storage: Retention ponds, detention basins, or underground systems must store the difference in runoff volume between pre-development and post-development conditions.
Discharge control: Outfall structures must be designed to release stored water at controlled rates that do not exceed pre-development peak flows.

Stormwater Quality

Florida requires treatment of stormwater runoff before it leaves your site. The ERP addresses water quality by requiring treatment of at least the first inch of rainfall — the "first flush" that carries the highest concentration of pollutants like sediment, oil, nutrients, and metals.

Common treatment methods accepted by the water management districts include:

Wet detention ponds: Permanent ponds that provide both storage and biological treatment through settling and nutrient uptake
Dry retention systems: Areas designed to retain stormwater and allow it to percolate into the ground, filtering pollutants through the soil
Swales: Vegetated channels that filter and convey stormwater while providing treatment through soil infiltration
Manufactured treatment devices: Engineered systems such as baffle boxes, hydrodynamic separators, and media filters that treat stormwater in constrained sites

Environmental Resource Protection

The "environmental resource" in ERP is not just a name — the permit evaluates impacts to wetlands, water bodies, listed species habitat, and other environmental resources. If your project affects wetlands, you must demonstrate that impacts have been avoided and minimized, and any unavoidable impacts must be mitigated through wetland creation or preservation.

When an ERP Is Required

Not every drainage project requires an ERP, but the threshold for triggering the requirement is lower than many property owners expect.

Projects That Require an ERP

New development creating more than specified impervious area: Thresholds vary by district, but in SFWMD, projects creating more than certain acreage of impervious surface or total project area trigger ERP requirements
Any work in or affecting wetlands: Even minor impacts to wetlands — filling, dredging, draining, or altering hydrology — require an ERP
Construction of new stormwater management systems: Retention ponds, detention basins, outfall structures, and other stormwater infrastructure require an ERP
Modification of existing permitted systems: Changes to the design or operation of a previously permitted stormwater system require an ERP modification
Commercial and multi-family development: Most commercial and multi-family residential projects exceed ERP thresholds
Residential subdivisions: Subdividing land for multiple homes typically requires an ERP for the subdivision's stormwater management system

Projects That May Be Exempt

The water management districts provide exemptions for certain activities:

Individual single-family homes: Construction of a single home on an existing lot of record, where the lot is part of a larger development that already has an ERP, is generally exempt
Maintenance of existing systems: Routine maintenance within the original design parameters of a permitted system does not require a new ERP
Agricultural activities: Certain agricultural practices are exempt, though this exemption is narrower than many landowners assume

For more on exemptions, see our guide on drainage permit exemptions in Florida. For broader permit information, visit our drainage permits guide.

The ERP Application Process

An ERP application is an engineering-intensive process that requires detailed technical documentation. Submitting a complete, well-prepared application is the single most important factor in getting timely approval.

Step 1: Site Assessment

Before designing your drainage system, you need a thorough understanding of existing site conditions:

Topographic survey: Accurate ground elevations across the entire site, including adjacent areas
Geotechnical investigation: Soil borings to determine soil type, permeability, and seasonal high water table elevation — critical in South Florida where the water table can be as shallow as 2 feet
Environmental survey: Wetland delineation, listed species survey, and identification of other environmental features
Floodplain analysis: FEMA flood zone determination and base flood elevation data

Step 2: Engineering Design

The drainage system must be designed to meet all ERP criteria simultaneously — water quantity, water quality, and flood protection. This requires:

Hydrologic modeling: Calculation of pre- and post-development runoff volumes and peak rates using approved methods
Hydraulic design: Sizing of pipes, structures, ponds, and outfalls to convey and store the required volumes
Water quality treatment design: Selection and sizing of treatment systems to meet the first-flush treatment requirement
Flood analysis: Verification that the project does not increase flood stages on or off site

Step 3: Application Submission

The complete ERP application package includes all engineering plans, calculations, environmental documentation, and the application form with fees. In SFWMD, applications can be submitted electronically through the ePermitting system.

Step 4: Review and Response

After submission, the water management district reviews the application and may issue Requests for Additional Information (RAIs). Each RAI must be responded to within a specified timeframe, usually 90 days. Multiple RAI cycles can extend the process significantly. Learn more about the SFWMD permit process specifically.

ERP Timeline and What to Expect

ERP timelines depend on project complexity, application completeness, and the reviewing district's workload.

Typical Timelines

General ERPs (minor projects): 30-60 days from complete application. These are streamlined permits for projects with minimal impact.
Standard ERPs (most projects): 90-180 days for straightforward projects with complete applications. This is the most common category for commercial and residential development drainage projects.
Complex ERPs: 6-18 months for large projects, those with wetland impacts, or projects in environmentally sensitive areas. Governing Board approval adds time.

Factors That Extend Timelines

RAIs: Each round of additional information requests adds 30-60 days. Poorly prepared applications can go through 3-4 RAI cycles.
Wetland impacts: Projects with wetland impacts require mitigation plans, which add review time and may involve coordination with federal agencies (Army Corps of Engineers).
Public opposition: Nearby property owners can challenge ERP applications, potentially triggering administrative hearings.
Agency coordination: Projects that require approvals from multiple agencies (SFWMD, county, FDEP, Army Corps) must coordinate timelines across all agencies.

ERP Conditions

ERPs are issued with conditions that govern construction and long-term operation of the stormwater management system. Common conditions include:

Construction must follow the approved plans exactly
An as-built certification by an engineer must be submitted after construction
The stormwater system must be maintained in perpetuity per the approved operation and maintenance plan
Annual reports or inspection certifications may be required for larger systems

When to Call a Professional

The ERP process requires professional engineering — there is no way around this. The calculations, plans, and technical documentation required for an ERP application can only be prepared by a Licensed Professional Engineer. But beyond the regulatory requirement, experienced engineering support makes the difference between a smooth process and months of frustrating delays.

Contact a professional engineer when:

You are planning any project that may trigger ERP requirements — get professional input early, before design decisions lock in approaches that may not be permittable
You have received an RAI from the water management district — RAIs require technical responses that address the specific engineering concerns raised
Your project involves wetlands — wetland permitting adds significant complexity that requires specialized knowledge
You need to modify an existing ERP — even seemingly minor changes to a permitted system may require a formal modification

Our Licensed Professional Engineers have prepared hundreds of ERP applications across Florida since 2004. With a 100% permit approval rate and deep experience with SFWMD and other Florida water management districts, we deliver applications that move through review efficiently. Explore our permit services or schedule a free consultation to discuss your project's ERP requirements. Call us at (347) 998-1464.

Frequently Asked Questions

What is the difference between an ERP and a building permit?

A building permit is issued by your local county or municipality and ensures construction meets the Florida Building Code. An ERP is issued by the water management district (such as SFWMD) and ensures your stormwater management system meets state water resource standards. Most drainage projects require both permits from separate agencies, and they operate on independent review timelines. Our permit services handle both simultaneously.

How much does an ERP cost in Florida?

ERP application fees paid to the water management district range from a few hundred dollars for general permits to several thousand for individual ERPs, depending on project size. The engineering cost to prepare the application — surveys, design, calculations, and plan preparation — typically ranges from $5,000 to $25,000+ for commercial projects. The investment in proper engineering is returned through faster approval, fewer RAIs, and avoiding costly redesigns.

Can an ERP be transferred to a new property owner?

Yes. ERPs can be transferred to new property owners through a formal transfer process with the water management district. The new owner assumes all permit conditions, including the obligation to maintain the stormwater management system. The transfer application is straightforward but must be completed — operating under someone else's ERP without transfer is a violation.

What happens if I build without an ERP?

Building without a required ERP is a serious violation in Florida. The water management district can issue stop-work orders, impose daily fines, require removal of unauthorized work, and mandate restoration of the site. In extreme cases, violations are referred to the FDEP for enforcement action. The cost of resolving an ERP violation almost always exceeds the cost of obtaining the permit properly from the start.

Do I need both an ERP and an Army Corps of Engineers permit?

If your project impacts wetlands or other "waters of the United States," you may need both a state ERP and a federal Section 404 permit from the Army Corps of Engineers. Florida has a State Programmatic General Permit (SPGP) agreement with the Army Corps that allows many projects to be processed through the state ERP process without a separate federal application. However, projects with larger wetland impacts may still require individual Army Corps review. Our engineers determine which permits are required during the initial project assessment.