A benthic-macroinvertebrate index of biotic integrity and assessment of conditions in selected streams in Chester County, Pennsylvania, 1998-2009

Evaluation of long-term trends in hydrologic and water-quality conditions, and estimation of water budgets through 2013, Chester County, Pennsylvania

“…The CC-IBI scores are based on a 0-100 scale with higher scores indicating better stream quality. The CC-IBI has site-specific scores that are based on benthicmacroinvertebrate samples collected from the network during 1998-2009 and related to reference conditions found in Chester County (Reif, 2012). Statistically significant upward trends in the CC-IBI were observed at the two sites in the Brandywine Creek watershedWest Branch Brandywine Creek at Modena, Pa. (01480617) and East Branch Brandywine Creek below Downingtown, Pa. (01480870) (table 19, fig.…”

“…Statistically significant upward trends in chloride have been documented at various stream locations in Chester County between 1998 and 2009 (Reif, 2012). (table 17).…”

“…Extreme events close to the sampling date are thought to have had the greatest effect on the macroinvertebrate community sampled in the study area. Samples collected after extreme low-flow or high-flow conditions generally had decreased CC-IBI (Reif, 2012).…”

“…Trends in biological diversity index were evaluated by Moore (1987), Hardy and others (1995), and Reif (2012). For this study, the Chester County Index of Biotic Integrity (CC-IBI) data from 1998 to 2013 were used for statistical analysis.…”