Assessment Comments
Assessment is based on results of: 1) IDNR ambient monthly monitoring near Hurstville (Maquoketa) (station 10490001; formerly station 290120) from January 2010 through December 2012, (2) USGS monitoring near Fulton, IA, from April-November 2012, and (3) 2006 and 2012 IDNR/SHL stream biological sampling data.
Basis for Assessment
SUMMARY: The Class A1 (primary contact recreation) are assessed (monitored) as "not supported" due to levels of indicator bacteria that exceed state water quality criteria (IR Category 5a). The Class B(WW1) aquatic life uses are assessed (monitored) as "fully supporting" (IR Category 2a). The fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this river reach (IR Category 3a). This assessment is based on results of IDNR ambient monthly monitoring near Hurstville (Maquoketa) (station 10490001; formerly station 290120) from January 2010 through December 2012, (2) USGS monitoring near Fulton, IA, from April to November 2012, and (3) on results of IDNR/SHL stream biological sampling in 2006 and 2012.
EXPLANATION: The Class A1 (primary contact recreation) uses are assessed (monitored) as "not supported" based on levels of indicator bacteria that exceed state water quality criteria. The Class A1 use designation was added to this river segment by the state of Iowa in March 2006; this change in use classification was approved by U.S. EPA in February 2008. The Class A1 (primary contact recreation) uses are assessed as “not supported” due to violations of Iowa’s water quality criteria for indicator bacteria. Results of IDNR monitoring from 2010 through 2012 showed that recreation season (March-November) geometric means based on the approximately eight samples collected per year were well above Iowa’s Class A1 water quality criterion of 126 orgs/100 ml: The annual recreation season geometric means for 2010, 2011 and 2012 are as follow: 2676, 596, and 293 E. coli orgs/100 ml. respectively. These geometric means far exceed the Class A1 criterion of 126 E. coli orgs/100 ml. Eighteen of the 25 samples (72%) exceeded Iowa’s single sample maximum criterion of 235 E. coli orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if the geometric mean is greater than 126 orgs/100 ml., the primary contact recreation uses are "not supported" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).
The Class B(WW1) aquatic life uses are assessed as “fully supporting” based on results of IDNR/SHL chemical/physical monitoring at the IDNR/SHL ambient monitoring station near Hurstville. Results of this monthly ambient water quality monitoring show no violations of Class B(WW1) water quality criteria for pH, dissolved oxygen, or ammonia-nitrogen in the approximately 36 samples analyzed for conventional pollutants during the 2010-2012 period. These results suggest "full support" of the Class B(WW1) aquatic life uses.
Results of USGS monitoring near Fulton in 2012 also suggest full support of the Class B(WW1) aquatic life uses. None of the approximately 12 samples collected from April to November 2012 violated Class B(WW1) criteria for dissolved oxygen or pH.
The Class B(WW1) aquatic life uses also remain assessed (evaluated) as “fully supporting” based on biological sampling in 2006 and 2012. This biological assessment was based on data collected in 2006 and 2012 as part of the IDNR/SHL stream sampling projects. 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 2006 FIBI score was 61 (good) and the 2006 BMIBI scores were 54 (fair) and 58 (good). The 2012 BMIBI score was 53 (fair). The aquatic life use support was assessed (evaluated) as fully supporting (=FS), 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 36 and the BMIBI BIC for this ecoregion is 51. This segment passed the FIBI BIC 1/1 times and passed the BMIBI BIC 3/3 times in the last seven years. This assessment is considered evaluated because the drainage areas (563, 590 mi2) above the sampling sites were greater than the maximum limit (500 mi2) that was used to calibrate the Iowa wadeable stream impairment criteria. Even though this site passed both the FIBI and BMIBI BICs, 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.
The fish consumption uses remain "not assessed" due to lack of fish contaminant monitoring in this river reach.
