Two of the most important reasons water quality monitoring is done are a) to determine compliance near point discharges and b) to assess changes in water quality and affects of pollution on a watershed from point and non- point sources. Most data are not captured into a central, publicly accessible database and do not go beyond the primary use; thus the availability of long-term data is critical for water quality assessments.
Volunteer water quality databases such as GLOBE and Rivers of Colorado Water Watch Network were compared to government agency databases such as EPA's STORET (STOrage and RETrieval) and USGS' NWIS (National Water Information System) in order to compare the spatial and temporal coverage of each. The reason for the comparison was to determine if the databases could be integrated in the future, according to recommendations made by the Intergovernmental Task Force on Monitoring Water Quality (ITFM).
An example of a national water quality assessment is the EPA 305(b) Report, which uses data primarily from state and government sources. In 1994, the EPA reported that only 17% of the river miles in the U.S. were surveyed for the EPA 305(b) Report, whereas 42% of the total lake acres were surveyed to make a national assessment.
Volunteer water quality databases are capable of filling recent temporal gaps in government agency databases.
NWIS and STORET site numbers are significantly higher than GLOBE; therefore GLOBE is currently not capable of filling in large spatial gaps due to the longevity of government agency databases.
