Statewide Stormwater Treatment Rule Development Background
 

Unmanaged urban stormwater creates a wide variety of effects on Florida’s surface and ground waters. Urbanization leads to the compaction of soil; the addition of impervious surfaces such as roads and parking lots; alteration of natural landscape features such as natural depressional areas which hold water, floodplains and wetlands; construction of highly efficient drainage systems; and the addition of pollutants from everyday human activities. These alterations within a watershed decrease the amount of rainwater that can seep into the soil to recharge our aquifers, maintain water levels in lakes and wetlands, and maintain spring and stream flows. Consequently, the volume, speed, and pollutant loading in stormwater that runs off developed areas increases leading to flooding, water quality problems, and loss of habitat.

To manage urban stormwater and minimize these impacts to our natural systems, Florida was the first state in the country to adopt a rule requiring the treatment of stormwater to a specified level of pollutant load reduction for all new development. Florida’s original stormwater rule was adopted in 1981 and went into effect in February 1982. The stormwater rule is a technology-based rule that relies upon four key components:

• A performance standard or goal for the minimum level of treatment
• Design criteria for best management practices (BMPs) that will achieve the performance standard
• A rebuttable presumption that discharges from a stormwater management system designed in accordance with the BMP design criteria will not cause harm to water resources.
• Periodic review and updating of BMP design criteria as more information becomes available to increase their effectiveness in removing pollutants.

Florida’s stormwater rules were developed to meet a performance standard of reducing the post-development stormwater pollutant loading of Total Suspended Solids by 80%, or by 95% for stormwater discharges directly into Outstanding Florida Waters. This level of treatment was selected for two reasons:

• To establish equitability in treatment requirements between point and nonpoint sources of pollution. The minimum level of treatment for domestic wastewater point sources was “secondary treatment” which equated to an 80% reduction in TSS.
• The costs of stormwater treatment greatly increased as the level of treatment rose above 80%.

In 1990, in response to legislation, the Department developed and implemented the State Water Resource Implementation Rule (originally known as the State Water Policy rule). This rule sets forth the broad guidelines for the implementation of Florida’s stormwater program and describes the roles of DEP, the water management districts, and local governments. The rule provides that one of the primary goals of the program is to maintain, to the degree possible, during and after construction and development, the predevelopment stormwater characteristics of a site. The rule also provides a specific minimum performance standard for stormwater treatment systems: to remove 80% of the post-development stormwater pollutant loading of pollutants “that cause or contribute to violations of water quality standards.” This performance standard is significantly different than the original one used in Florida’s stormwater treatment rules. However, for a variety of reasons, the BMP design criteria in the stormwater or environmental resource permitting rules of DEP or the WMDs were never updated to achieve this level of treatment.

In 1999, the Florida Watershed Restoration Act, Section 403.067, F.S., was enacted leading to the implementation of Florida’s water body restoration program and the establishment of Total Maximum Daily Loads (TMDLs). A TMDL is the maximum amount of a specific pollutant that can be discharged to a waterbody while maintaining water quality standards. A TMDL must be established and implemented for all impaired waters – water bodies or water body segments that are not currently meeting their applicable water quality standards. Since the program began over 2000 impairments have been verified in Florida’s surface waters with nutrients identified as the major cause of impairments. Additionally, nutrient enrichment of ground waters and springs has been recognized as a major concern in Florida.

To address the growing problem of nutrient enrichment of Florida’s surface and ground waters, a number of initiatives have been undertaken by DEP, the WMDs, and the Florida Department of Agriculture and Consumer Services. One such initiative is the Statewide Stormwater Treatment Rule which will increase the level of nutrient removal required of stormwater treatment systems serving new development. This rule will be based upon a performance standard that the post-development nutrient load will not exceed the nutrient load from natural, undeveloped areas.