Going With The Flow: Navigating Florida’s New Stormwater Requirements
“An important statewide stormwater rule became fully effective in Florida in December 2025,” says Pape-Dawson Principal Jamie Poulos, P.E., LEED AP. “We’ve been following it for years to stay in front of it…but now that it’s hit, we’ve been actively educating our clients about the change.”
Florida’s Senate Bill 7040 directed the new restrictions found in the state’s administrative code, now in effect. The details are complex—and though Jamie will happily talk through the specifics, he says the rule boils down to stricter nutrient-loading reduction requirements for water runoff and additional operation and maintenance provisions.
When rainwater falls, the ground absorbs some of it. The rest is runoff, which carries phosphorus and nitrogen as it moves downstream. Too much of those nutrients can harm ecosystems and waterbodies, and built-up areas tend to increase those levels. “That comes from fertilizers people use, reclaimed water for irrigation, soaps from driveway car washing, and other aspects of life that come with development,” Jamie explains. “There’s also naturally occurring nitrogen that falls to the ground out of the atmosphere, but impermeable surfaces cause a greater volume of runoff, which means more nutrients hitting water bodies.”
“The rule isn’t a shock to our clients,” says Jamie, “But we help them understand the challenges, the costs, and the tradeoffs available for a stormwater management plan to meet the new rules.”
Calculating Percentages of Runoff
The new Florida requirement takes a “two-pronged approach,” forcing developers to commit to nutrient removal to the highest of two standards. The first standard requires removing a percentage of total runoff of phosphorus and nitrogen based on a simple chart with round numbers. Standard sites need to remove 80% of total phosphorus and 55% of total nitrogen from projected runoff, for instance.
More-stringent specifications apply to special areas. Heightened protections for Outstanding Florida Water, a long-standing designation for pristine lakes, river systems, and other water bodies, help keep them healthy. Impaired Waters are the opposite: places where water quality needs to be preserved because it’s already compromised.
Determining Before and After Land Use Categories
The other standard uses a table that establishes nutrient concentrations based on pre-development versus post-development Event Mean Concentrations (EMCs) and loadings. The rule includes a table for EMCs for various pre- and post-development land uses. The table predictably sets high runoff nitrogen and phosphorus values for developed areas, but lower ones for most undeveloped locales, such as forests and prairies. The task for developers using this standard is first to determine the land use category for the existing lands, which isn’t always clear-cut. Differences in how the land is categorized can result in significantly different loading and, therefore, design requirements.
“We dig into databases, maps, site visits, and environmental reports to accurately assess existing site conditions,” Jamie says. “Different land classifications carry different baseline nutrient values, so establishing the right starting point is an important part of stormwater planning and regulatory compliance.”
The final requirement for nutrient removal is the more stringent of the two: either an across-the-board removal of a stipulated overall percentage of nutrients, or a reduction in runoff nutrients to the level of their pre-development land-use category.
Designing to Decrease Nutrients in Runoff
Whichever standard prevails, developers must include stormwater treatment methods to meet it. Under the previous rule, they could simply dig a wet or dry pond, says Jamie. “They might give up 15% of the site to the pond, but they’d need the fill material anyway, they could label it as an amenity, and it would be very low maintenance, long term.”
Under the new rules, he adds, in many cases “that’s not going to do it anymore.” While ponds can supply part of the solution, most other options entail more cost and greater ongoing maintenance. Floating wetland mats, for example, incur not only an initial investment, but also need their vegetation harvested multiple times a year. Filtration systems need their media renewed periodically.
Some features are simple, such as littoral shelves planted with vegetation that takes nutrients from the water. Others are high-tech: one potential solution uses an active pond-management system that tracks weather data and retains water until it expects a rainfall system. Since nutrients settle and biodegrade over time, a deliberate pre-release flushes cleaner water downstream and makes room to catch nutrient-dense runoff.
Understanding the Takeaways
Jamie recommends appreciating the new rules’ complexity, but emphasizes a few main points:
- Learn exemptions and grandfathering provisions, since those can provide significant benefits in some cases
- Keep current on nutrient best management practices because they will remain fluid in 2026 and beyond
- Consider creative water treatment methods to meet new requirements and understand the trade-offs for various alternatives
A regulatory change this significant affects each development differently, says Jamie. “Our job is to guide clients through the details, understand their priorities, and help them choose the options that are best for them.”