Alum efficacy 11 years following treatment: phosphorus and macroinvertebrates

ABSTRACTSteinman AD, Hassett MC, Oudsema M, Rediske R. 2018. Alum efficacy 11 years following treatment: phosphorus and macroinvertebrates. Lake Reserv Manage. 34:167—181.Internal phosphorus loading and benthic macroinvertebrate community structure were analyzed at 4 sites in Spring Lake, Michigan, ˜11 yr following an alum treatment. Phosphorus (P) release rates, benthic macroinvertebrate community structure, sediment chemistry, and water quality variables (total dissolved solids, pH, dissolved oxygen, water clarity) were compared to measurements taken previously (2003/2004: pre-alum application, 2006: 8 mo post-alum application, and 2010: 5 yr post-alum application) at the same sites and using comparable methods. Total phosphorus (TP) concentrations in surface water samples from 2016 (38—45 νg/L) were similar to those measured in 2006 and 2010 (20—80 νg/L) at all sites; however, 2016 TP concentrations in the near-bottom water at the 2 deeper sites were elevated (˜250 and 1,000 νg/L, respectively) compare...