Assessment Comments
Assessment is based on: (1) results of the statewide survey of Iowa lakes conducted from 2009-2012 by Iowa State University (ISU), (2) results of the statewide ambient lake monitoring program conducted in 2008 by University Hygienic Laboratory (UHL), (3) information from the IDNR Fisheries Bureau, (4) results of the IDNR-county voluntary beach monitoring program in 2004, (5) results of U.S. EPA/IDNR turtle contaminant monitoring in 2009, and (6) results of U.S. EPA/Iowa DNR fish contaminant (RAFT) monitoring in 2011.
Basis for Assessment
SUMMARY: The Class A1 (primary contact recreation) uses are assessed (monitored) as “fully supported” (IR 2a). The Class B(LW) aquatic life uses are also assessed (evaluated) as “fully supported” (IR 2a). Information from the Iowa DNR Fisheries Bureau indicates that the previous impairment due to siltation has been addressed and removed. The fish consumption (Class HH) uses are assessed (monitored) as "partially supported" (IR Category 5a) due to issuance of fish consumption advisory. Sources of data for this assessment include: (1) results of the statewide survey of Iowa lakes conducted from 2009-2012 by Iowa State University (ISU), (2) results of the statewide ambient lake monitoring program conducted in 2008 by University Hygienic Laboratory (UHL), (3) information from the IDNR Fisheries Bureau, (4) results of the IDNR-county voluntary beach monitoring program in 2004, (5) results of U.S. EPA/IDNR turtle contaminant monitoring in 2009 and fish tissue monitoring in 2011, and (6) information from the Iowa DNR fisheries management biologist (B. Wallace) at Yellow Smoke Lake.
Note: A TMDL for siltation at Yellow Smoke Lake was prepared by IDNR and approved by EPA in 2002; thus, this waterbody was placed into IR Category 4a (TMDL approved) for the 2004 assessment/listing cycle. Because all Section 303(d) impairments identified for the 2012 assessment/listing cycle (siltation) were addressed by the TMDL, this waterbody remained in IR Category 4a (TMDL approved) from the 2004 through 2010 assessment/listing cycles. Due to in-lake and watershed work conducted from 2003 to 2008 correct this impairment, and due to information on condition of the fishery at this lake, the siltation impairment was removed for the 2012 Integrated Reporting cycle. Thus, the aquatic life uses are considered “fully supported” (IR Category 2a).
EXPLANATION: Results of IDNR county beach monitoring from 2004 suggest that the Class A1 uses are assessed (evaluated) as “fully supported.” Levels of indicator bacteria Yellow Smoke Lake Beach were monitored approximately once per week during the primary contact recreation season (May through August) of 2004 (13 samples) as part of the IDNR county 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) all thirty-day geometric means for 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 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.” Also, 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 Yellow Smoke Lake Beach, the geometric means of all 5 thirty-day periods during the summer recreation season of 2004 were below the Iowa water quality standard of 126 E. coli orgs/100 ml. Also, no samples exceeded Iowa’s single-sample maximum criterion (235 E. coli orgs/100 ml) in 2004. 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 suggest that the Class A1 (primary contact recreation) uses at Yellow Smoke Lake are “fully supported.” Using the median values from these surveys from 2008-2012 (approximately 14 samples), Carlson’s (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 42, 41, and 49 respectively for Yellow Smoke Lake. According to Carlson (1977) the Secchi depth, total phosphorus, and chlorophyll a values place Yellow Smoke Lake in the mesotrophic category. These values suggest extremely low levels of chlorophyll a and suspended algae in the water, exceptional water transparency, and extremely low levels of phosphorus in the water column.
The level of inorganic suspended solids is extremely low at Yellow Smoke Lake and suggests that non-algal turbidity does not cause water quality problems. The median inorganic suspended solids concentration at Yellow Smoke Lake was 1.6 mg/L, and ranked 6th of the 134 monitored lakes.
Data from the 2008-2012 ISU and UHL surveys suggest a very small population of cyanobacteria exists at Yellow Smoke Lake, which does not cause water quality problems at the lake. These data show that cyanobacteria comprised only 41% of the phytoplankton wet mass at this lake. The median cyanobacteria wet mass (4.5 mg/L) and ranked 8th of the 134 lakes sampled.
The Class B(LW) (aquatic life) uses are now assessed (evaluated) as “fully supported.” Information from the IDNR Fisheries Bureau indicates that the previous impairment due to siltation in the upper arm of this lake was been addressed and corrected. According to IDNR Fisheries, over the last 10 years, the Crawford County Conservation Board was a awarded a fish habitat grant to rectify the siltation problem at Yellow Smoke Lake. As a result, silt was removed from the upper end of the lake via backhoe, the shoreline was armored in the upper end, a partial sediment trap/basin was installed in the very upper end of the lake, and an additional sediment pond was constructed on private property further up in the lake’s watershed. Also, pea gravel/sand bed was placed in the north arm of the lake to create bluegill spawning habitat. A 2010 fish survey shows that the fish populations at this lake are well balanced, healthy, and that natural reproduction is occurring on a consistent basis.
Data from the ISU and UHL lake surveys continue to show good chemical water quality at Yellow Smoke Lake. Results from these surveys show that during 2008-2012 there were no violations of the Class B(LW) criterion for ammonia in 14 samples, dissolved oxygen in 14 samples, or pH in 14 samples. These results also suggest “full support” of the Class B(LW) aquatic life uses at Yellow Smoke Lake.
The assessment of support of the fish consumption uses is changed from “partially supported” (impaired) to "fully supporting" based on results of U.S. EPA/IDNR fish contaminant monitoring in 2012 and 2014. The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of support of fish consumption uses in Iowa’s rivers and lakes. The fish contaminant data generated from the 2011 RAFT sampling conducted at Yellow Smoke Lake showed that levels of mercury are sufficiently high for concern and thus justified issuance of a one meal/week fish consumption advisory in 2013. Results from the 2011 sampling showed that the average level of mercury in the sample of largemouth bass muscle tissue (0.7 ppm) far exceeded the 1 meal/week trigger level (0.30 ppm) as defined in Iowa’s revised (2007) fish consumption advisory protocol. According to the Iowa DNR/Iowa Dept. of Public Health fish advisory protocol, the single occurrence of contaminant above an advisory trigger level does not typically result in issuance of an advisory. Such an advisory is issued only after follow-up monitoring confirms that contaminant levels exceed the advisory trigger level. Becasue, however, the average level of mercury was nearing the "do not eat" advisory threshold of 1.0 ppm, Iowa DNR issued the one-meal/week consumption advisory without the need for a follow-up/confirmation sampling. Follow up monitoring was conducted in 2012 on largemouth bass. The average level of mercury in the tissue plug samples from five largemouth bass was 0.218 ppm (SD=0.074 ppm; maximum=0.331 ppm) and was below Iowa's advisory threshold of 0.3 ppm. According to Iowa DNR assessment/listing guidelines, however, two consecutive samples showing average contaminant levels below the advisory threshold are needed before an advisory can be rescinded. The average level of mercury in the next (2014) sample of five largemouth bass from Yellow Smoke was 0.194 ppm (SD=0.093 ppm; Max. = 0.29 ppm). Similar to the results from the 2012 sampling, the 2014 average level of mercury was below the consumption advisory threshold of 0.3 ppm. Because the the 2014 sample was the second consecutive sampling that showed that average levels of mercury are below the advisory threshold, the fish consumption impairment due to mercury is proposed for delisting for the 2014 IR.
U.S. EPA/IDNR contaminant (RAFT) monitoring at Yellow Smoke Lake in 2009 showed that levels of contaminant in turtle tissue were below Iowa's consumption advisory thresholds. The composite samples of shoulder tissue from snapping turtle had low levels of contaminants. Levels of primary contaminants in the shoulder tissue of snapping turtle were as follows: mercury: 0.122 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. Thus, the turtle contaminant data generated from the 2009 RAFT sampling show that the levels of contaminants do not exceed any of Iowa's advisory thresholds for a one-meal/week advisory (0.3 ppm for mercury, 0.2 ppm for PCBs, and 0.6 ppm for chlordane).
