Expert Query

Expert Query empowers users to access surface water quality data from the Assessment and TMDL Tracking and Implementation System (ATTAINS), encompassing Assessment decisions (under Clean Water Act Sections 303(d), 305(b), and 106) and Action data like Total Maximum Daily Loads (TMDLs), Advance Restoration Plans (ARPs), and Protection Approaches.  For the latest changes in Expert Query, view our update page.

The tool supports querying and downloading data within and across organizations (states or tribes), such as querying all the data within an EPA region or all nutrient TMDLs nationally. It also allows users to download national ATTAINS data extracts in various formats, such as Excel files or CSV files. 

However, it's crucial to be aware of certain complexities inherent in the data and the querying process. Users are cautioned against direct comparisons between states due to differences in water quality standards and assessment methodologies. 

While Expert Query facilitates data querying, it lacks built-in summary capabilities. Users are encouraged to download and summarize data, but use caution when relying on row counts, as duplicate entries may occur. The complexity arises from multiple tables that have many-to-many relationships. 

For example, the following table result can occur with many-to-many relationships in the Assessment profile. This example contains four rows with two assessment units, three assessment unit/parameter combinations, and four assessment unit/use combinations giving an incorrect count of waterbody/parameter combinations: 

Assessment Unit ID	Use	Parameter
AU_1	Primary Contact Recreation	ESCHERICHIA COLI (E. COLI)
AU_1	Primary Contact Recreation	FECAL COLIFORM
AU_1	Secondary Contact Recreation	ESCHERICHIA COLI (E. COLI)
AU_2	Primary Contact Recreation	FECAL COLIFORM