Streamwatch Project

Changes Over Time

For each site there was a wide range of MAIS scores among years (points indicate MAIS in each year sampled). Depending on the year sampled many sites ranged from Good to Fair or from Fair to Poor. In most instances, a site that averaged Good was never Poor and a site that averaged Poor was never Good. Sites 19, 0, and 7 were an exception to this rule because they had at least one year that rated Good, Fair and Poor. This emphasizes the importance of having multi-year studies to correctly characterize conditions. Of all sites sampled more than one year, Site 11 is the only one that did not ever score in the Poor category. In contrast, Sites 16 and 21 rated Poor in all the years they were sampled. Move cursor over graph to see an enlarged view.

Within each site water quality varied over time but there were no trends indicating sites were improving or becoming more degraded since 1991 when the study started.  The following graph of the four sites on the East Branch illustrates that water quality is not changing in a meaningful way over time. Move cursor over graph to see an enlarged view.

Site 21 on the Lower Mainstem may be the only location suggesting water quality is improving but conditions at this site are still Poor (MAIS = 5.9 in 2000). This trend should be reexamined since this site was only sampled 5 years (instead of 10-12 years like most sites).