EPA regulations allow states to place certain impaired water bodies into Category 4b of the Integrated Report Categories instead of Category 5 – Impaired and needs a TMDL. The Florida Watershed Restoration Act (section 403.067(4), Florida Statutes) explicitly allows DEP to not list impaired waters under Category 5 if they already have control programs in place that will ensure water quality standards will be restored. These types of waterbodies – impaired, but with control programs already being implemented to reduce pollutant loadings – are placed in assessment Category 4b for Clean Water Act section 303(d) reporting purposes.

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Select map inset to view and download Reasonable Assurance Plan documents.       

Sunset at Island Cove, Pinellas County Aquatic Preserve
Lignumvitae Key
John Moran Lake Wales Ridge
Mangrove tunnel in Tampa bay Aquatic Preserves

 

 

Mosquito Lagoon Reasonable Assurance Plan 
a black mangrove colonizes the edge of a spoil island in Indian River Lagoon
 

 

Reasonable Assurance Plan Progress (Category 4b)

 

4b Process StepDescription 
Plan Initiated
  • Entities have contacted the department expressing interest to pursue a 4b plan.
  • Participating partnering entities (public/private) have been identified.
  • Public meeting(s) has been scheduled to kick off development of the plan.
Develop RA Plan
  • Identify responsible participating entities.
  • Delineate the geographic boundary the plan will include:
  • Identify point and non-point source pollutants.
  • Determine appropriate water quality targets for the parameters and waterbodies of concern.
  • Determine necessary nutrient load reductions.
  • Identify projects to provide the reasonable assurance that the proposed. management actions can achieve the designated uses of the waterbody.
  • Calculate credits/reductions for ongoing and planned projects.
  • Identify procedures for monitoring, compliance assessment and reporting.
  • Establish key indicators that will be assessed to provide assurance of progress in towards achieving restoration.
  • Establish an implementation timeframe for the plan.
  • Identify possible funding mechanisms.

 

Finalize RA Plan

  • The plan has been presented to all interested parties and participating entities.
  • Public comments have been requested and received.
  • Plan has been agreed to by all participating entities.
Adopt RA Plan by Secretarial Order
  • Plan has been approved and signed by DEP's secretary.
Implement RA Plan
  • Projects (structural and non-structural) are moving forward and being implemented.
  • Monitoring is continuing.
Evaluate Progress
  • Progress reports are prepared and provided to the participating entities and the department.
Progress Demonstrated
  • Project implementation is verified.
  • Project implementation has resulted in load reductions.
  • Improvements in water quality are observed.
Evaluate Progress
  • Plan is updated as needed to ensure progress continues (e.g., pollutant loads re-evaluated, project progress and monitoring status are evaluated, etc.).
Continued Progress Demonstrated
  • Project implementation is verified.
  • Project implementation has resulted in load reductions.
  • Improvements in water quality are observed.
RA Target Attained
  • Load/concentration target has been achieved.

 

Last Modified: Wednesday, Apr 29, 2026 - 12:56pm