Lower Pine Lake IA 02-IOW-758

Assessment Comments

Assessment is based on results of lake surveys and surveys by IDNR Fisheries Bureau.

Basis for Assessment

Both fishable and swimmable uses were assessed as PS for the following reasons:  (1) average levels of secchi depth, chl-a, and TSS are better than overall averages for the 86 SPO impoundments sampled in 1990 and 1992; level of total-P, however, is greater than overall average + 1 SD.   (2) summer kill frequency est at 10%, (3) Bachmann et al.  (1991) report that siltation in Lower Pine L.  was a serious problem prior to construction of Upper Pine L.; i.e., est that Lower Pine lost 48% of volume since contruct.  in 1922.   The rel large amount of shallow water in the east half of the lake may explain high levels of total-P, (4) Bachmann et al.  (1994) state that "excessive blue-green algae blooms may reduce swimming activity during July and August."  Thus, organic enrichment leading to summer kills and excessive algae impair the fishable and swimmable uses; both problems are ultimately related to agricultural NPS.