Lost Island Lake IA 06-LSR-1632

Results of IDNR beach monitoring from 2012 through 2013 suggest that the Class A1 uses are "Fully Supported." Levels of indicator bacteria at Lost Island - Huston Park Beach were monitored once per week during the primary contact recreation seasons (May through September) of 2012 (12 samples) and 2013 (15 samples), as part of the IDNR beach monitoring program.   According to IDNR’s assessment methodology two conditions need to be met for results of beach monitoring to indicate “full support” of the Class A1 (primary contact recreation) uses: (1) the geometric mean of the samples from each recreation season of the three-year assessment period are less than the state's geometric mean criterion of 126 E.  coli orgs/100 ml and (2) not more than 10% of the samples during any one recreation season exceeds the state's single-sample maximum value of 235 E.  coli orgs/100 ml. If a sampling season geometric mean exceeds the state criterion of 1000 orgs/100 ml during the three-year assessment period, the Class A1 uses should be assessed as “not supported.” Also, if a sampling season geometric mean exceeds the state criterion of 126 orgs/100 ml during the three-year assessment period and/or if significantly more than 10% of the samples in any one of the three recreation seasons exceed Iowa's single-sample maximum value of 235 E.  coli orgs/100 ml, the Class A1 uses should be assessed as “partially supported.” This assessment approach is based on U.S.   EPA guidelines (see pgs 3-33 to 3-35 of U.S.   EPA 1997b).

At Lost Island - Huston Park Beach, the geometric means from 2012 and 2013 were all below the Iowa water quality standard of 126 E.  coli orgs/100 ml.   The geometric mean was 31 E.  coli orgs/100 ml in 2012 and 19 E.  coli orgs/100 ml in 2013.   The percentage of samples exceeding Iowa's single-sample maximum criterion (235 E.  coli orgs/100 ml) was 17% in 2012 and 0% in 2013.   None of these are significantly greater than 10% of the samples and therefore do not suggest impairment of the Class A1 uses.   According to IDNR's assessment methodology and U.S.  EPA guidelines, these results suggest "Fully Supported" of the Class A1 uses.

For the 2016 assessment/listing cycle, the Class A1 (primary contact recreation) uses of Lost Island Lake are assessed (monitored) as "fully supported" based on information from the ISU lake survey. Using the median values from these surveys from 2010-2014 (approximately 15 samples), Carlson 's (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 63, 63, and 65 respectively for Lost Island Lake. According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Lost Island Lake in the Eutrophic category. These values suggest moderately high levels of chlorophyll a and suspended algae in the water, moderately poor water transparency, and high levels of phosphorus in the water column. The data show no violations of the Class A1 criterion for pH in 15 samples. While the TSI value for Secchi depth in Lost Island Lake is below the impairment trigger of 65 for the 2016 reporting cycle, Lost Island Lake was listed as "not supporting" the Class A1 uses for the 2014 reporting cycle due to aesthetically objectionable conditions caused by poor water clarity.   Based on IDNR's assessment methodology, median-based TSI values for Secchi depth must be 63 or less for two consecutive assessment/listing cycles before a lake can be removed from the state’s Section 303(d) list (IR Category 4a).    Therefore, Lost Island Lake remains assessed as "not supported" due to poor water clarity for the 2016 assessment cycle.  

Note:  A TMDL for turbidity at Lost Island Lake was prepared by IDNR and approved by EPA in 2009; thus this lake is placed in IR Category 4a (TMDL approved) for the 2016 assessment/listing cycle.      

The level of inorganic suspended solids was moderately high at Lost Island Lake, and does suggest that non-algal turbidity may contribute to the impairment at this lake. The median level of inorganic suspended solids in Lost Island Lake (6.19 mg/L) was ranked 97th among the 138 lakes by the ISU lake survey.

Data from the 2010-2014 ISU lake survey suggest a large population of cyanobacteria exists at Lost Island Lake, which suggests the potential for an impairment due to nuisance aquatic life These data show that cyanobacteria comprised 98% of the phytoplankton wet mass at this lake. The median cyanobacteria wet mass (57.2 mg/L) was ranked 120th of the 138 lakes sampled. This median is in the worst 25% of the 138 lakes sampled. The presence of a large population of cyanobacteria at this lake suggests a potential violation of Iowa's narrative water quality standard protecting against the occurrence of nuisance aquatic life. This assessment is based strictly on the distribution of the lake-specific median cyanobacteria values from 2010-2014. Median levels greater than the 75th percentile of this distribution were arbitrarily considered to represent potential impairment. No other criteria exist, however, upon which to base a more accurate identification of impairments due to cyanobacteria. Assessments based on level of cyanobacteria will be considered "evaluated" (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence) to account for this lower level of confidence.

The Class B(LW) (aquatic life) uses are assessed (evaluated) as “partially supported” due to a fish kill on June 9, 2007.   The kill was identified as a natural fish kill of crappies due to post-spawning stress.  According to IDNR’s assessment/listing methodology, the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period (2010-2012) indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired.”  If a cause of the kill was not identified during the IDNR investigation, or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated.”  Such assessments, although suitable for Section 305(b) reporting, lack the degree of confidence to support addition to the state Section 303(d) list of impaired waters (IR Category 5).   Waterbodies affected by such fish kills will be placed in IR subcategories 2b or 3b and will be added to the state list of waters in need of further investigation.  

Results of the ISU lake survey from 2010-2014 show there were no violations of the criterion for ammonia in 15 samples(0%), no violations of the criterion for dissolved oxygen in 15 samples(0%), and no violations of the criterion for pH in 15 samples(0%). Based on IDNR's assessment methodology these violations are not significantly greater than 10% of the samples and therefore suggest (fully supported/monitored) of the Class B(LW) uses of Lost Island Lake.

The level of support of the Class HH-fish consumption uses is changed from “fully supporting” to “not assessed” due to the age of the data upon which the previous assessment was based.  The previous assessment was based on results of U.S. EPA / IDNR fish tissue (RAFT) monitoring at Lost Island Lake in 2005.   The composite samples of fillets from walleye and carp had low levels of contaminants.   Levels of primary contaminants in the composite sample of walleye fillets were as follows: mercury: 0.0244 ppm; total PCBs: <0.09 ppm; and technical chlordane: <0.03 ppm.   Levels of primary contaminants in the composite sample of carp fillets were as follows: mercury: 0.031 ppm; total PCBs: <0.09 ppm; and technical chlordane: <0.03 ppm.   Because these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is considered “evaluated” (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence).    The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of the degree to which Iowa’s lakes and rivers support their fish consumption uses.    The fish contaminant data generated from the 2005 sampling conducted in this lake show that the levels of contaminants do not exceed any of the advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody.

Note: A lake restoration project beginning in 2008 and is still ongoing.