This raster data layer represents the total effluent coming from onsite waste disposal systems (OSDS) (e.g. cesspools and septic tanks). OSDS point data was obtained from UH/DOH (Bob Whittier & El Kadi) that estimates effluent flux from each TMK parcel with OSDS. We converted the points to raster by summing nutrient flux values within 500 m x 500 m pixels. Then focal statistics was used to calculate the total flux within a 1.5 km radius of each oceanic cell. Units are in gallons/day per km2. This layer was developed as part of a geospatial database of key anthropogenic pressures to coastal waters of the Main Hawaiian Islands for the Ocean Tipping Points project (http://oceantippingpoints.org/). Ocean tipping points occur when incremental changes in human use or environmental conditions result in large, and sometimes abrupt, impacts to marine ecosystems. The ability to predict and understand ocean tipping points can enhance ecosystem management. The goal of the Hawaii case study of the Ocean Tipping Points project was to gather, process and map spatial data on environmental and anthropogenic drivers of coral reef ecosystem states. Understanding direct anthropogenic drivers is critical for coral reef management and implementing policies to protect ecosystem services generated by coral reefs. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.