NST is a stormwater-focused company that partnered with the Florida Department of Transportation (FDOT) to provide regional stormwater treatment services for the benefit of its customers and the environment.

NST permits, constructs, operates and maintains regional stormwater ponds and can permanently reserve for its customers a specified volume of treatment capacity to offset the stormwater treatment requirements associated with any size project.

NST invests private capital to improve the water quality treatment provided in existing FDOT ponds, creating excess stormwater treatment “credit” that can be transferred to other projects in the watershed. Through efficient, system-wide management of stormwater infrastructure, and the deployment of state-of-the-art “smart-pond” technology, NST delivers flexible, cost-effective, resilient and environmentally sustainable stormwater solutions to its customers.

NST provides its customers with turnkey, long-term stormwater ownership and management services, freeing up land or capital normally invested in constructing, operating and maintaining stormwater infrastructure. Included with the purchase of offsite stormwater treatment services from NST are the perpetual maintenance and regulatory costs of the offsite treatment. By centralizing the management of regional ponds utilizing advanced treatment technology, NST delivers efficient, professional services and improved regional water quality.

National Stormwater Trust has a limited amount of Stormwater Nutrient Credits available immediately in the Tampa Bay Watershed and has access to thousands of additional FDOT stormwater ponds across Florida to generate credits and meet your smart stormwater management needs. Permitted stormwater capacity is available now, and it takes approximately 90 days to complete a purchase. The rest of the Tampa-Orlando market and the Space Coast regions will be opening by the end of 2025.

• USGS Hydrologic Unit Maps
• FDEP HUC-12 Basins Map
• NST GIS HUC-12 Boundaries

Similar to wetland mitigation credits, stormwater nutrient credits (SNCs) allow a portion or all of the stormwater treatment requirements for a development to be satisfied in an off-site location within the same watershed. When SNCs are available within the same HUC-12 sub-watershed boundary, property owners may be able to off-set a portion of stormwater requirements. Purchasing SNCs can be more cost effective by reducing the space required for stormwater management onsite. The additional space can be used for other purposes.

For pricing and availability, please email the project location and the quantity of required treatment of TN and TP in kg/year to info@nationalstormwater.com. 

Yes, in most cases for commercial, industrial, or multi-family developments, you can purchase stormwater treatment capacity from NST and free up additional land for development. This eliminates maintenance and other costs associated with traditional stormwater ponds and underground vaults. 

Yes! NST can professionally manage your existing ponds and improve their performance with ‘Smart Pond’ technology to increase capacity, reduce flooding risk, and improve the removal of harmful nutrients. If you would like to remove and redevelop an existing pond and replace it with offsite stormwater treatment, please get in touch with us and we will help you develop a plan. 

It is not complicated at all! 

1. Contact NST with the location and credits needed for offsite compensatory treatment. 
2. NST will send you a reservation agreement for the stormwater nutrient credits that you need, then we permit your stormwater treatment capacity in one of NST’s regional treatment facilities. 
3. You pay one lump sum fee for only the stormwater nutrient credits that you need, which eliminates the time and cost of constructing your own pond and all future operation, maintenance, and repair expenses. 

The entire process is usually completed in 30 to 60 days. 

How the Rule Works and Implementation Timeline

With the implementation of Florida’s updated stormwater rule, design flexibility has increased—particularly through the use of off-site compensatory treatment and Regional Stormwater Management Systems (RSMS). However, these strategies may lead to the discharge of partially treated stormwater runoff to wetlands.

While this approach offers permitting efficiency, it also raises a key technical question:
How do we demonstrate that a wetland has the assimilative capacity to receive this runoff without causing an adverse impact?

📜 Regulatory Background: Rule 62-611, F.A.C.

The good news is wetlands are consumers of nutrients. In fact, wetlands need nutrients to thrive. The issue is determining the total amount of nutrients that can be assimilated by a wetland system while remaining within healthy limits. The answer lies in Chapter 62-611, F.A.C., Florida’s Wetlands Application Rule, which outlines procedures to evaluate wetland assimilative capacity. Originally developed for wastewater treatment wetlands, this rule can also be applied to stormwater discharges—especially in the context of project designs that discharge partially treated runoff to natural wetlands while using off-site compensatory treatment within the same watershed.

🔬 Key Wetland Capacity Criteria

Rule 62-611 sets specific hydraulic and nutrient loading limits for discharges to artificial treatment wetlands and natural (receiving) wetlands. We will use the more stringent limits for natural wetlands in this procedure:

• Hydraulic Loading:
  ≤ 2 inches/week (annual average)
  Detention Time: > 14 days (annual average)
• Nutrient Loading (Assimilative Capacity):
  • Total Nitrogen (TN): < 25 g/m²/year
  • Total Phosphorus (TP): < 3.0 g/m²/year
• Discharge Limits:
  • To Receiving Wetlands: TN = 3 mg/L, TP = 1 mg/L

🚧 How This Applies to Projects

Typical event mean concentrations (EMCs) for project runoff are already below the discharge limits. For example, the EMCs for roadway projects are:

• TN: 1.52 mg/L
• TP: 0.20 mg/L

This means that for many projects, discharges to wetlands may comply with Rule 62-611 without additional nutrient treatment, as long as the wetland has sufficient assimilative and hydraulic capacity.

📌 Why This Matters

By applying the wetland assimilative loading criteria under Rule 62-611, engineers can demonstrate regulatory compliance for wetland discharges from partially treated stormwater systems. This can support more cost-effective stormwater designs, reduce the need for additional BMPs or treatment infrastructure, and allow the use of off-site compensating treatment to achieve full compliance with the new, more stringent performance criteria later this year.

📂 Downloadable Design Example

To help illustrate this approach, we’ve provided a downloadable spreadsheet example that walks through the process of evaluating a wetland’s assimilative and hydraulic capacity for a representative stormwater discharge scenario. Note that other developments that discharge to the same wetland system may add to the cumulative loading, so provisions for calculating this loading are included in the spreadsheet.

📥 Download the Design Example Spreadsheet

🧰 Tips for Stormwater Engineering Consultants:

• Use Rule 62-611 procedures to evaluate wetland assimilative loading capacity.
• Ensure discharge concentrations and loading rates from your project are within allowable thresholds for the receiving wetlands.
• Consider the cumulative loading from other developments within the same basin that may discharge to the same wetlands.
• Larger wetland systems are more likely to assimilate additional nutrient loading without adverse impact.
• Coordinate with the WMD early in design to confirm consistency with the ERP Rules and Applicant’s Handbook.

NST has prepared an outline of exemption and grandfathering provisions of the new rule (located in Section 3.1.2 of Applicant’s Handbook, Volume 1). We’ve also included a couple of examples to help you better understand some likely scenarios. 

Additional Information:

Grandfathering Provisions: What You Need to Know

Purpose: To distinguish the Regional Stormwater Management System (RSMS) framework (currently implementable and actively used by NST) from the Water Quality Enhancement Area (WQEA) framework (still under rule development), focusing on applicability, regulatory readiness, and credit generation mechanisms.

Comparison Table: RSMS vs. WQEA

Common Features of Both Frameworks

• Standalone ERP Permit: Each facility type is permitted as a discrete ERP project.
• Excess Treatment = Credits: Credits are based on treatment beyond what’s required for the developed drainage area or based on water quality “lift” (determined like a mitigation bank – with success criteria and monitoring).
• Defined Service Area: Credit use is restricted to a defined service area.
• Long-Term Assurance: Owners of an RSMS and WQEA must demonstrate perpetual maintenance, financial assurance, and responsible party designation.
• Professional Operator: Must be a capable entity with performance verification protocols in place.
• Tracking & Ledger: Both frameworks require a credit ledger that documents generation, allocation, and availability.
• Use Restrictions:
o May not offset localized water quality impacts
o Not applicable to water quantity or floodplain requirements
o Credits cannot double-count for ERP and BMAP reductions

Use Case Guidance and Observation

• Developers needing immediate nutrient credit solutions should turn to NST’s RSMS approach, which is fully actionable today. With the new stormwater rule deadline looming and more stringent performance requirements, the availability of off-site nutrient credits will be essential to avoiding costly development impacts or time-consuming project redesigns.