Hooper Area Pond IA 04-LDM-1084

Assessment Comments

Assessment is based on: (1) results of the statewide survey of Iowa lakes conducted from 2004 through 2007 by Iowa State University (ISU), (2) results of the statewide ambient lake monitoring program conducted from 2005 through 2008 by University Hygienic Laboratory (UHL), and (3) information from the IDNR Fisheries Bureau.

Basis for Assessment

SUMMARY: This lake is not designated for Class A1 (primary contact recreation) uses.   The Class B(LW) (aquatic life) uses are assessed (monitored) as “fully supported.”  Fish consumption uses remain “not assessed” due to a lack of fish contaminant monitoring at this lake.   Sources of data for this assessment include (1) results of the statewide survey of Iowa lakes conducted from 2004 through 2007 by Iowa State University (ISU), (2) results of the statewide ambient lake monitoring program conducted from 2005 through 2008 by University Hygienic Laboratory (UHL), and (3) information from the IDNR Fisheries Bureau.

EXPLANATION: Results from the ISU statewide survey of Iowa lakes and the UHL ambient lake monitoring program suggest that the moderately high levels of algal turbidity may threaten full support of the Class B(LW) uses of Hooper Area Pond.    Despite this potential threat, water transparency remains relatively good at this lake, and IDNR Fisheries feels that the Class B(LW) uses remain “fully supported.”

Using the median values from the ISU and UHL lake surveys from 2004 through 2008 (approximately 20 samples), Carlson’s (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 62, 69, and 64 respectively for Hooper Area Pond.   According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Hooper Area Pond in between the eutrophic and the hypereutrophic categories.   These values suggest high levels of chlorophyll a and suspended algae in the water, moderately poor water transparency, and moderately high levels of phosphorus in the water column.  

The levels of inorganic suspended solids at this lake were relatively low and do not suggest an impairment due to non-algal turibidity.   The median level of inorganic suspended solids in Hooper Area Pond (3.0 mg/L) was the 49th lowest median of the 132 lakes sampled by the ISU and UHL programs.

Data from the 2004-2008 ISU and UHL surveys suggest a moderate population of cyanobacteria exists at Hooper Area Pond, which does not contribute to an impairment due to nuisance aquatic life at this lake.   These data show that cyanobacteria comprised only 22% of the phytoplankton wet mass at this lake.   The median cyanobacteria wet mass (5.3 mg/L) was the 29th lowest of the 132 lakes sampled.  

The Class B(LW) (aquatic life) uses are assessed as “fully supported” based on information from IDNR’s Fisheries Bureau and results from the ISU and UHL lake surveys.   The ISU and UHL lake surveys data from 2004-2008 show no violations of the Class B(LW) criteria for ammonia in 20 samples, or dissolved oxygen in 20 samples.   The pH data show 1 violation of the Class B(LW) criterion for pH in 20 samples (5%).   Based on IDNR’s assessment methodology these violations are not significantly greater than 10% of the samples and therefore suggest full support of the Class B(LW) uses.   Hooper Area Pond was impaired due to significant violations of the pH criterion for the 2006 assessment/listing cycle.   Based on IDNR's assessment methodology 2 assessment cycles of not having significantly more than 10% of the samples exceed the pH criterion are necessary to suggest full support of the Class B(LW) uses.   Because both the 2008 assessment and the 2010 assessment show that there were not significantly greater than 10% of the samples exceeding the pH criterion, the pH impairment is suggested for de-listing for the 2010 assessment cycle.

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