“…The relationships between Secchi transparency and other parameters, such as chlorophyll and nutrient enrichment, have been the subject of numerous investigations (Brezonik and Shannon 1971, Beeton and Edmondson 1972, Larson 1972, Dillon and Rigler 1974, Carlson 1977, Havens et al 1999, Stadelmann et al 2001, Erlandsson and Stigebrandt 2006. Secchi depth is used as one of the parameters to calculate various trophic indices, including the Trophic Status Index (TSI) by Carlson 1977 and the Trophic Level Index (TLI) by Burns et al 1999; both indices were used in the Boulder Basin analyses (LaBounty and Burns 2005).…”