Turkey River IA 01-TRK-148

The Class A1 (primary contact recreation) uses are assessed as "not supported" based on levels of indicator bacteria that slightly exceeded state water quality criteria.  Two of the three recreation season (March-November) geometric means of indicator bacteria (E. coli) in the 48 samples collected at the IDNR ambient monitoring station near Garber during the recreational seasons of 2012 through 2014 as part of IDNR ambient monthly monitoring and as part of the Turkey River Watershed Project exceeded the Iowa water quality criterion (126 orgs/100 ml) to protect primary contact recreation uses.  The 2012 geometric mean was 140 orgs/100 ml, and the 2013 geometric mean was 252 orgs/100 ml.  The 2014 geometric mean (115 orgs/100 ml), however was below the Class A1 standard.  Seventeen of the 48 samples (35%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. 

Results of USGS bacterial monitoring at the Garber monitoring station during the 2012-2014 period also showed that two of the three recreation season (March-November) geometric means based on the 19 samples collected were above Iowa’s Class A1 water quality criterion of 126 orgs/100 ml.  Although the 2012 geometric mean of 104 orgs/100 ml was below the Class A1 standard, the 2013 geometric mean (434 orgs/100 ml and the 2014 geometric mean (382 orgs/100 ml both slightly exceeded the standard.  Seven of the 19 USGS samples (37%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. 

Results of IDNR monitoring at Hwy 52 (STORET station 15220020) showed similar results with two of the three recreation season geometric means exceeding the Class A1 standard based on the 23 samples collected from 2012 to 2014.  The 2012 geometric mean was 125 orgs/100 ml, and the 2013 geometric mean was 505 orgs/100 ml; both of these geometric means exceed the Class A1 criterion of 126 orgs/100 ml.  The 2014 geometric mean (69 orgs/100 ml), however, was well-below the Class A1 standard.  Nine of the 23 USGS samples (39%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. 

In conclusion, the results of bacterial monitoring at these three stations during the 2012-2014 period show that six of the nine recreation season geometric means exceed Iowa’s Class A1 geometric mean criterion of 126 orgs/100 ml.  According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if a recreation season geometric mean is greater than 126 orgs/100 ml., the primary contact recreation uses are assessed as impaired (see pgs 3-33 to 3-35 of U.S. EPA 1997b).  Thus, the Class A1 (primary contact recreation) uses of this segment are assessed as “partially supported”.  In addition, the percentages of samples that exceed Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml was significantly greater than 10% in all three datasets, thus also indicating impairment of the Class A1 uses.  The magnitude of impairment in this stream segment, however, is slight:  the maximum geometric mean for the 2012-2014 period was 505 orgs/100 ml, and three of the nine geometric means during the 2012-2014 period met the Class A1 criterion. 

Results of chemical/physical water quality monitoring by IDNR, USGS, and U.S. EPA do not suggest impairment of the Class B(WW1) aquatic life uses.  Monitoring at the IDNR, USGS, and LTRMP stations showed no violations of Class B(WW1) water quality criteria for conventional pollutants or ammonia in the approximately 50 samples analyzed at the IDNR ambient monitoring station at Garber, the approximately 20 samples analyzed at IDNR station at Hwy 52, and in the approximately 30 samples analyzed at the USGS station at Garber.  None of the combined 97 samples collected at these three monitoring programs from 2012-2014 violated Iowa’s aquatic life criteria for chloride or sulfate.  In addition, none of the 31 samples analyzed during this three-year period for banned pesticides (e.g., DDT, and dieldrin) by USGS violated the respective Class B(WW1) criteria. 

Results of biological monitoring conducted by the IDNR Fisheries Bureau in 2002 and by IDNR/SHL in 2003, 2011, 2012, 2013 and 2014, however, suggest that the Class B(WW1) aquatic life uses should remain assessed (evaluated) as “partially supported”.  A series of biological metrics that reflect stream water quality and habitat integrity were calculated from the biocriteria sampling data.  The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species collected in the stream sampling reach.  The biological metrics were combined to make a fish community index of biotic integrity (FIBI) and a benthic macroinvertebrate index (BMIBI).  The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).  The 2003 REMAP FIBI score was 75 (excellent).  The 2002 Fisheries FIBI was 39 (fair).  The 2011-2014 BMIBI scores were 52 (fair) and 62, 65, 68 (all good).  The aquatic life use support was assessed (evaluated) as partially supporting (=PS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008.  The FIBI BIC for this ecoregion is 52 and the BMIBI BIC for this ecoregion is 61.  This biological assessment is considered “evaluated” because the drainage area (1553 and 1606 mi2) above this sampling sites was greater than the maximum limit (500 mi2) that was used to calibrate the Iowa wadeable stream impairment criteria.  Even though the one out of two samples failed to meet the FIBI BIC and this site passed the BMIBI BIC (3/4), it is uncertain as to whether or not this segment is meeting the aquatic life criteria because it doesn’t fall in the calibrated watershed size.  This potential impairment is not appropriate for Iowa’s Section 303(d) list of impaired waters (Integrated Report Category 5) but is appropriate for IR Category 3b of Iowa’s Integrated Report and Iowa’s list of waters in need of further investigation. 

Fish consumption uses remain assessed (monitored) as “partially supported” (IR Category 5a) based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring near Garber in 2011 and 2012 and on issuance of a one meal per week consumption advisory in 2013.  This advisory was issued due to two consecutive samplings showing that levels of mercury in predator fish (smallmouth bass) exceeded the threshold for a one meal/week advisory (0.3 ppm).  The average level of mercury in the samples of smallmouth bass collected in 2011 was 0.38 ppm, and the average level in the samples of smallmouth bass collected in 2012 was 0.47 ppm.  Based on these results, a consumption advisory was issued in 2013.  The existence of, or potential for, a fish consumption advisory is the basis for assessing the degree to which Iowa’s lakes and rivers support their fish consumption uses.  Because a one meal per week fish consumption advisory was issued for this waterbody, the fish consumption uses are assessed (monitored) as “partially supported” (IR Category 5a).