Water-Quality Assessment of Two Slow-Moving Sandy-Bottom Sites on the Saw Mill River, New York

Abstract

We selected 2 sites on the Saw Mill River and conducted biological assessments of water quality using macroinvertebrate composition. Assessment metrics used were: Shannon-Weiner diversity, evenness, species richness, Hilsenhoff biotic index (HBI), Ephemeroptera—Plecoptera—Trichoptera richness (EPT), and non-Chironomidae and Oligochaete (NCO) richness. Water temperature, pH, conductivity, total dissolved solids, dissolved oxygen, and water flow and velocity were not significantly different across sites. Shannon-Weiner diversity values were 2.32 (evenness = 0.20) for Chappaqua and 2.68 (evenness = 0.31) for Hawthorne. Species and NCO richness for Chappaqua were 49 and 22, respectively, and for Hawthorne were 44 and 23, respectively. HBI was 7.99 for Chappaqua and 7.69 for Hawthorne. Both sites had equal EPT values of 5. Based on macroinvertebrate assessment indices, we classified water quality at these sites as non-impacted.