Crane Creek IA 01-TRK-212

The presumptive Class A1 (primary contact recreation) uses are assessed as "not supported" based on levels of indicator bacteria that slightly exceeded state water quality criteria. Based on the approximately eight monthly samples collected during the recreation seasons of 2012, 2013, and 2014, the geometric means at station CRA-50 are as follow: 404, 2,590, and 448 E. coli orgs/100 ml., respectively. All three geometric means exceed the Class A1 criterion of 126 orgs/100 ml. Nineteen of the combined 23 samples (83%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and DNR’s assessment/listing methodology, if a recreation season geometric mean exceeds the respective water quality criterion, the contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as “impaired.”

The Class B(WW2) aquatic life uses remain assessed (evaluated) as “fully supported" based on biological data collected in 2009 and 2013 as part of the DNR/SHL stream biocriteria project. A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biological 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 2009 FIBI score was 58 (good) and the BMIBI score was 57 (good). The 2013 FIBI score was 68 (good) and the BMIBI score was 56 (good). The aquatic life use support was assessed as fully supporting (=FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports. The non-riffle habitat FIBI BIC is 44 and the artificial substrate BMIBI BIC is 52. This segment passed the FIBI and BMIBI BICs 2/2 times in the last eight years. The biological impairment criteria were determined from a statistical analysis of biological data collected at stream ecoregion reference sites from 1994-2008. This aquatic life assessment is now considered "evaluated" based on a change in the 2010 DNR assessment methodology. DNR now requires a segment have two or more biological samples collected from the segment in multiple over a recent five-year period to be considered “monitored”. This segment had multiple samples collected in the previous eight years (2009-2016). However, despite this change in assessment methodology and type, this waterbody remains in IR Category 2a.

Results of chemical/physical water quality monitoring conducted at station CRA-50 from April 2012 to November 2014 show no violations of Class B(WW2) water quality criteria for dissolved oxygen (24 samples), ammonia (16 samples), pH (24 samples), temperature (24 samples), or chloride (16 samples). Thus, these monitoring results suggest that the Class B(WW2) aquatic life uses should be assessed as "fully supported".