Belva Deer Lake IA 03-NSK-6241

Assessment Comments

Assessment is based on: (1) results of the statewide survey of Iowa lakes conducted in 2009 through 2012 by Iowa State University (ISU), (2) results of the statewide ambient lake monitoring program conducted in 2008 by University Hygienic Laboratory (UHL), (3)and information from the IDNR Fisheries Bureau.

Basis for Assessment

SUMMARY: NOTE: Belva Deer Lake is not designated for Class A1 uses in the Iowa Surface Water Classification.   The Class B(LW) (aquatic life) uses are assessed (monitored) as “fully supported.”  Fish consumption uses are “not assessed.”  Sources of data for this assessment include results of the statewide survey of Iowa lakes conducted in 2009 through 2012 by Iowa State University (ISU), results of the statewide ambient lake monitoring program conducted in 2008 by University Hygienic Laboratory (UHL), and  information from the IDNR Fisheries Bureau.

EXPLANATION: Results from the ISU and UHL lake surveys show good water quality at Belva Deer Lake.  Using the median values from these surveys from 2008 and 2012 (approximately 15 samples), Carlson’s (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 56, 58, and 55 respectively for Belva Deer Lake.   According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Belva Deer Lake in the eutrophic category.   These values suggest relatively low levels of chlorophyll a and suspended algae in the water, relatively good water transparency, and relatively low levels of phosphorus in the water column.  

The level of inorganic suspended solids was low at this lake and does not suggest impairment due to high non-algal turbidity.   The median inorganic suspended solids concentration at Belva Deer Lake was 2.0 mg/L, which ranked 7th of the 134 monitored lakes.

Data from the 2008-2012 ISU and UHL surveys suggest a relatively small population of cyanobacteria exists at Belva Deer Lake.   These data show that cyanobacteria comprised 96% of the phytoplankton wet mass at this lake.   The median cyanobacteria wet mass (25.0 mg/L) and ranked 86th of the 134 lakes sampled.  

The Class B(LW) (aquatic life) uses are assessed (monitored) as “fully supported” based on information from the IDNR Fisheries Bureau, and results from the ISU and UHL lake surveys.   Information from the IDNR Fisheries Bureau suggests that water clarity is very good at Belva Deer Lake.   The ISU and UHL lake survey results show good chemical water quality at Belva Deer Lake.   During 2008 through 2012 there were no violations of the Class B(LW) criterion for ammonia (15 samples), dissolved oxygen (15 samples), or pH (15 samples).   Based on IDNR’s assessment methodology these results suggest full support of the Class B(LW) uses of Belva Deer Lake.  

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this lake.