An official website of the United States government.

We've made some changes to If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

How to Upload Geospatial (GIS) Data in ATTAINS

This document explains how to upload geospatial (or GIS) files representing Assessment Unit locations and extents to ATTAINS for processing. The uploaded files will be processed to National Hydrography Dataset Plus (NHDPlus) catchments using an automated Catchment Indexing Process (CIP) Tool. The relationship between each Assessment Unit and associated catchment(s) will be provided in an output table (catchment crosswalk table), that can then be used in conjunction with geospatial analyses.

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.