The Florida Department of Environmental Protection (FDEP) has adopted a watershed management approach to managing water resources in Florida. This approach is based on naturally occurring hydrologic features such as river basins, as opposed to political or regulatory boundaries, thus promoting the management of entire natural systems. In addition, this approach strives to increase cooperation among programs and provide consistent environmental management, while maintaining the flexibility to address local and regional issues and implement Total Maximum Daily Loads (TMDLs). One of the primary goals established in the Tampa Bay National Estuary Program Comprehensive Conservation and Management Plan is to restore seagrass extent in the bay to levels similar to those observed in the 1950s. The Nitrogen Management Strategy seeks to prevent future impacts due to excessive nitrogen loadings to Tampa Bay. The TBEP adopted the 'hold the line' strategy, which seeks to maintain loadings at or below the 1992-1994 levels. Local government partners agreed to preclude increases in future nitrogen loadings to the bay to aid in this effort. In order to better address the FDEPs watershed management approach to water resource management, the Tampa Bay Estuary Program is currently examining loading estimates at the major basin level. The objectives of this report are as follows: provide model based estimates of nitrogen loading for the existing period (1998) and the future period (2010), and describe the nitrogen load apportionment process adopted by the TBEP for the 2000-2004 period. This report provides brief descriptions of the methods used to derive the model based total nitrogen loadings from major basins for 1998 and 2010. The model based loading estimates are then used to apportion nitrogen load reductions/preclusions among jurisdictions in each major basin.