State Programs. Minnesotas water quality programs are designed to address the states standards for seven designated types of use. The seven designated classes of water use in Minnesota, from the most stringent to the least stringent water quality standards, are:
For each designated use, increasingly stringent sets of water quality parameters exist. Depending on the level of standards met, the water body is described as fully supporting, partially supporting or not supporting. The fishable use classification includes two sets of standards, one for aquatic life support and the other for fish consumption, which are separately assessed. Aquatic life support standards are based on ambient standards for conventional pollutants and toxicity levels for dissolved solids on aquatic organisms. Stream reaches classify as partially supporting if standards are violated 11- 25% and not supporting if violations exceed 25%. Fish consumption standards are based on analyses of fish tissue. Table 5.3 shows standards for fish consumption.
The PCA cautions the users of its biennial reports that sites are not selected by a random process, and frequency of sampling and choice of parameters vary from site to site. Therefore the water quality assessment cannot be considered or used to represent the overall water quality of Minnesotas rivers and streams (PCA, 1994). The PCA initiated a random-site, statistically-based monitoring effort in 1996 to give a valid, unbiased assessment of overall water quality in Minnesota. At program initiation, 80 sites in the St. Croix basin were monitored for basic water chemistry, habitat, fish, and macro invertebrates.
Table 5.3 Fish Contaminant Advisory Levels
*Tetrachlorodibenzodioxin, commonly known as dioxin
The PCA monitors rivers water quality routinely in compliance with state law and section 305(b) of the Clean Water Act. Section 305(b) requires that each state submit a biennial report to Congress on their progress toward meeting the goals of the act. Approximately 6% of Minnesotas total river miles are assessed each year. The program has been aimed primarily at monitoring point source pollution. For many years, 78 stations were monitored, the majority of which were located on the states largest rivers. Tributary sampling sites generally are located near their mouths. Monitoring activities also included an additional 15 stream sites from a specific geographic area of emphasis; this rotates every three years from the southern to northeastern to northwestern portions of the state (PCA, 1992).
In 1996, the PCA routine monitoring program consisted of 90 sites statewide which were monitored for 10 months each year for two years of a five-year cycle. The Minnesota Department of Health analyzes the samples for standard and site-specific water-quality parameters. (Parameters are listed in Appendix C.)
The PCA recently made several changes in its monitoring program, including reduced reliance on routine, fixed-station monitoring and increased efforts on longitudinal surveys of streams of particular interest and statistically-based monitoring. The PCAs monitoring activities include basin assessments that take into account relationships within a watershed, including nonpoint sources of pollution. In addition, to measure a rivers ability to support its aquatic community, biological monitoring is being used to complement chemical monitoring. The PCAs water quality data are stored on the EPAs STORET database. Monthly data exist for the 1968 through 1978 period. Prior to 1968, sampling was sporadic, and since 1978, samples have not been collected in December, January, and February.