Fla. Stat. § 373.4142
State surface water quality standards applicable to waters of the state, as defined in s. 403.031, do not apply within a stormwater management system which is designed, constructed, operated, and maintained for stormwater treatment in accordance with a valid permit or noticed exemption issued pursuant to chapter 62-25, Florida Administrative Code; a valid permit or exemption under s. 373.4145 within the Northwest Florida Water Management District; a valid permit issued on or subsequent to April 1, 1986, within the Suwannee River Water Management District or the St. Johns River Water Management District pursuant to this part; a valid permit issued on or subsequent to March 1, 1988, within the Southwest Florida Water Management District pursuant to this part; or a valid permit issued on or subsequent to January 6, 1982, within the South Florida Water Management District pursuant to this part. Such inapplicability of state water quality standards shall be limited to that part of the stormwater management system located upstream of a manmade water control structure permitted, or approved under a noticed exemption, to retain or detain stormwater runoff in order to provide treatment of the stormwater. The additional use of such a stormwater management system for flood attenuation or irrigation does not divest the system of the benefits of this exemption. This section does not affect the authority of the department and water management districts to require reasonable assurance that the water quality within such stormwater management systems will not adversely impact public health, fish and wildlife, or adjacent waters.
Fla. Stat. § 373.4142