Williamson Pond IA 04-LDM-1058

Assessment Comments

Assessment based on surveys by IDNR Fisheries Bureau and lake monitoring data.

Basis for Assessment

Both were assessed as PS for the following reasons:  (1) BPJ of DNR Fisheries; (2) results of monitoring in 1990 show that average levels of secchi depth, total-P, and TSS are worse than overall averages for the 116 SPOLs sampled in 1990 and 1992 +/- 1 SD; i.e., lake has some of the poorest water quality of any SPOL in Iowa.   Average level of chl-a was very low, probably due to shading from suspended sediment; (3) according to Bachmann et al.  (1994), lake has a relatively high sedimentation rate (4.8 cm/yr) and a rel.  short life expectancy (50 years); (4) they also report an impairment of "high turbidity"; (5) they also report no use for swimming at this lake.   Much of the watershed is relatively steep, and some soil erosion can be expected.