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Nutrient Offset Buy Down Calculation
In nutrient strategy areas, a developer not meeting the loading rate targets on their site has the option to ‘buy down’ a portion of their nutrient load from a DWR approved nutrient offset provider to meet loading rate targets.
The developer’s nutrient loading is calculated using the development plan and a nutrient accounting tool. The developer must only use the accounting tool that is approved for their watershed/basin. The following are the tools and the areas for which they are approved:
Using the appropriate accounting tool, the developer calculates their new development nutrient loading. For the development to proceed, it must meet the loading rate targets or, at a minimum, the offsite threshold requirements for their watershed [see Table]. Once that obligation is met, they may buy down the remainder of their nutrient loads to meet the loading rate targets. The following calculation procedures are a guide to help illustrate the buy-down calculation method.
Also, a reporting form also needs to be submitted to the local government by the developer to characterize their development project.
Sample Buy Down Calculation (No Delivery Factor): Neuse, Tar-Pamlico, and Falls (Reporting form link)
For the Neuse, Tar-Pamlico, or Falls nutrient strategy areas, the amount of offset needed to purchase is the difference between the nutrient load from the development and the loading rate target. This amount is then multiplied by 30 years. The following is an example illustrating the calculation process:
Sample Buy Down Calculation (Delivery Factor): Jordan Watershed (Reporting form link)
Buy down amounts in the Jordan Watershed must include a factor to account for the amount of nutrients being delivered to the Lake. This factor can be found on the Division’s map of Jordan Delivery Factors. The following is an example of the offset calculation for the Jordan Watershed: