Methods for Calculating Project Reductions

Tools and Guidance for Calculating Total Nitrogen (TN) and Total Phosphorus (TP) Reductions for Restoration Projects

This website describes the DEP methods to calculate total nitrogen (TN) and total phosphorus (TP) reductions for watershed restoration, when site-specific information is not available. This guidance and calculation methods are related to the development and implementation of BMAPs, 4e plans, and 4b/reasonable assurance plans (RAPs). 

Statewide Best Management Practice (BMP) Efficiencies for Crediting Projects in Basin Management Action Plans (BMAPs) and Alternative Restoration Plans (Draft – September 2021)

This document outlines methods to calculate TN and TP reductions for urban stormwater loads related to surface watershed restoration, when site-specific information is unavailable. These calculation methods represent typical BMP performance in Florida, which may be useful to stakeholders when selecting BMPs to achieve nutrient load reductions related to the development and implementation of BMAPs, 4e plans, and 4b/reasonable assurance plans (RAPs). DEP assigns nutrient removal efficiencies and nutrient credits to BMPs on a case-by-case basis, using the information as a guide during the decision-making process.

BMP Verification Helper (Microsoft Excel file)

DEP has prepared a BMP Verification Helper Microsoft Excel file to assist stakeholders in providing project information. The first tab can be used to reference the earliest acceptable date for projects, by BMAP, and determine what kind of supporting documentation is required for verification of nutrient credits based on project type. Project types are organized by category in an easy-to-navigate table in the second tab.

Guidance for Amending Urban Soils with Organic Amendments and Field Sheet

These guidance documents provide information on how removal credits can be calculated for soil amendment efforts in BMAP areas. This provides a template for developing credits, and outlines methods and approaches that could be used by responsible entities. DEP recommends contacting BMAP staff prior to initiating any effort to develop a local urban soil amendment credit approach.

Indian River Lagoon (IRL) BMAP Muck Removal Project Credit Guidance and Tool for Calculating BMAP Credit Eligibility

This guidance document provides an example of how removal credits are calculated for muck removal projects in the IRL BMAP. While the calculations only apply in the three IRL BMAP areas, this document provides a template for projects in other areas and includes the requirements and analysis necessary to develop reduction credits. For other regions, local data and assessments must be used. DEP recommends contacting BMAP staff prior to initiating effort to develop muck removal guidance for another area or region.

IRL BMAP Protocol for Shoreline Stabilization TMDL Project Credit

This guidance document provides an example of how removal credits are calculated for shoreline stabilization (utilizing practices and principals similar to “living shorelines”) projects for a specific project site. While the approach only applies to the three IRL BMAP areas, this protocol provides a template for projects in other areas and includes the requirements and analysis necessary to develop reduction credits. For other regions, local data and assessments must be used. DEP recommends contacting BMAP staff prior to initiating any effort to identify a site-specific shoreline stabilization protocol.

IRL Aquatic Vegetation Harvesting Credit Guidance

This guidance document provides an example of how removal credits are calculated for mechanical removal or harvest of aquatic vegetation rather than treatment with herbicides or other control mechanisms. In addition, we have also provided a basic calculation spreadsheet tool to assist with credit estimates for this kind of project. While the calculations only apply in the three IRL BMAP areas, this document provides a template for projects in other areas and includes the requirements and analysis necessary to develop reduction credits. For other regions, local data and assessments must be used. DEP recommends contacting BMAP staff prior to initiating effort to develop aquatic vegetation harvesting guidance for another area or region.

OSTDS Calculations for BMAPs and Information on OSTDS

This spreadsheet tool has been developed to assist BMAP stakeholders with quantifying nutrient reductions associated with OSTDS Phase Out or Enhancement Projects. It should be noted that these calculations are estimates, DEP recommends contacting BMAP staff prior to initiating any formal effort to implement a project to be included in a BMAP.

For further information on the impacts of OSTDS to the aquatic environment, we recommend the following resources: 

• About  Septic Systems
• Caring for Septic Systems
• Maintaining Septic Systems
• Failing Septic Systems
• Inspecting Septic Systems
• Septic System Compliance
• Paying for Septic Systems
• Environmental/Public Health Impacts from Septic Systems
• IFAS OSTDS Information