Pollmiller Park Lake IA 03-SKM-888

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), (3) information from the IDNR Fisheries Bureau, and (4) results of the IDNR-county voluntary beach monitoring program from 2006 through 2008.

Basis for Assessment

SUMMARY: The Class A1 (primary contact recreation) uses are assessed (monitored) as “fully supported.”  The Class B(LW) (aquatic life) uses are assessed (monitored) as “fully supported.”  Fish consumption uses remain “not assessed.”  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), (3) information from the IDNR Fisheries Bureau, and (4) results of the IDNR-county voluntary beach monitoring program from 2006 through 2008.

EXPLANATION: Results of IDNR county beach monitoring from 2006 through 2008 suggest that the Class A1 uses are assessed (monitored) as "fully supported."  Levels of indicator bacteria at Pollmiller Park Lake beach were monitored approximately once per week during the primary contact recreation seasons (May through August) of 2006 (14 samples), 2007 (11 samples), and 2008 (14 samples) as part of the IDNR county beach monitoring program.   According to IDNR’s assessment methodology, all thirty-day geometric means for the three-year assessment period must be less than the state’s geometric mean criterion of 126 E.   coli orgs/100 ml for results of beach monitoring to indicate “full support” of the Class A1 (primary contact recreation) uses.    If a 5-sample, 30-day geometric mean exceeds the state criterion of 126 orgs/100 ml during the three-year assessment period, the Class A1 uses should be assessed as “not supported”.    This assessment approach is based on U.S.   EPA guidelines (see pgs 3-33 to 3-35 of U.S.   EPA 1997b).    
  
At Pollmiller Park Lake beach, the geometric means of all 21 thirty-day periods during the summer recreation seasons of 2006, 2007, and 2008 were below the Iowa water quality standard of 126 E.  coli orgs/100 ml.   There were also no samples that exceeded Iowa’s single-sample maximum criterion (235 E.  coli orgs/100 ml) in 2006, 2007, or 2008.   According to IDNR’s assessment methodology and U.S.  EPA guidelines, these results suggest full support of the Class A1 (primary contact recreation) uses.

Results from the ISU and UHL lake surveys also suggest that the Class A1 uses at Pollmiller Park Lake are “fully supported.”  Using the median values from these surveys from 2004 through 2008 (approximately 24 samples), Carlson’s (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 53, 55, and 57 respectively for Pollmiller Park Lake.   According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Pollmiller Park Lake in the eutrophic category.   These values suggest relatively low levels of chlorophyll a and suspended algae in the water, very good water transparency, and relatively low levels of phosphorus in the water column.  

The level of inorganic suspended solids is low at this lake and does not suggest impairment due to high non-algal turbidity.   The median inorganic suspended solids concentration at Pollmiller Park Lake was 2.0 mg/L, which was the 32nd lowest of the 132 monitored lakes.

Data from the 2004-2008 ISU and UHL surveys suggest a relatively small population of cyanobacteria exists at Pollmiller Park Lake, which does not suggest impairment at this lake.   These data show that cyanobacteria comprised 59% of the phytoplankton wet mass at this lake.   The median cyanobacteria wet mass (4.7 mg/L) was also the 27th lowest of the 132 lakes sampled.  

The Class B(LW) (aquatic life) uses are assessed 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 good at Pollmiller Lake, however, sedimentation remains a concern on the southeast side of the lake.   The ISU and UHL lake surveys show that during 2004-2008 there were no violations of the Class B(LW) criterion for ammonia in 24 samples, or dissolved oxygen in 24 samples.   There were 2 violations of the Class A1,B(LW) criterion for pH in 24 samples (8%).   Based on IDNR’s assessment methodology these violations are not significantly greater than 10% of the samples and therefore do not suggest impairment of the Class B(LW) uses of Pollmiller Park Lake.

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