This layer represents a proxy for sediment input to the nearshore marine environment from recent construction sites. Data is derived from NOAA Coastal Change Analysis Program (C-CAP) High Resolution Change dataset from 2005 to 2010 (except for Oahu and Lanai where data is for 2005 – 2011). (http://coast.noaa.gov/ccapftp/). We extracted pixels that changed from any undeveloped class to impervious surface during the time period and calculated the area of new impervious surface within NHD HU12 watersheds. The area of new impervious surface was dispersed offshore using a decay function similar to that used for the OTP sediment layer. Finally values were rescaled from 0 -1 as this layer is a unitless proxy. 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.