Water-quality data-collection activities in Colorado and Ohio; Phase III, evaluation of existing data for use in assessing regional water-quality conditions and trends

During the past several years, a growing number of questions have been raised by members of Congress and others about the status of current waterquality conditions in the Nation, trends in water quality, and the major factors that affect water-quality conditions and trends. One area of particular interest and concern has been the suitability of existing water-quality data for addressing these types of questions at regional and national scales. In response to these questions and concerns, the U.S. Geological Survey began a pilot study in Colorado and Ohio to (1) determine the characteristics of current water-quality data-collection activities of Federal, State, regional, and local agencies and universities; and (2) determine how well the data from these activities, collected for various purposes and using different procedures, can be used to improve our ability to address the aforementioned questions.

Colorado and Ohio were chosen for the pilot study because they represent regions with different types of water-quality issues and programs. The results of the study are specific to the two States and are not intended to be extrapolated to other States.

The study was divided into three phases whose objectives were:

Phase I Identify and inventory 1984 water-quality data-collection programs, including costs, in Colorado and Ohio, and identify those programs that meet a set of broad criteria for producing data that potentially are appropriate for water-quality assessments of regional and national scope.

Phase II Evaluate the quality assurance of field and laboratory procedures used to produce the data from programs that met the broad criteria of Phase I.

Phase III Compile the qualifying data from Phase II and evaluate the extent to which the resulting data base can be used to address selected water-quality questions for the two States.

This report presents the results of Phase III, focusing on (1) the number of measurements made at each data-collection site for selected constituents, (2) the areal distribution of those sites that have sufficient data for selected types of analyses, and (3) the availability of key ancillary information such as streamflow to address broad-scope questions such as:

1. What are existing water-quality conditions?
2. Has the water quality changed? and
3. How do existing water-quality conditions and changes in these conditions relate to natural factors and human-induced activities?