The presumptive Class A1 (primary contact recreation) uses remain assessed (evaluated) as "not supported" due to violations of Iowa’s water quality criteria for indicator bacteria. The geometric mean of E. coli in the 14 samples collected during the 2006 and 2007 recreational seasons (March 15 to November 15) at TMDL station NuCr1 was 4,087 orgs/100 ml.; ten of the 14 samples (71%) 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 the geometric mean of E. coli is greater than the Class B(WW2) geometric meancriterion of 630orgs/100 ml., the primary contact recreation uses should be assessed as "not supported" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).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 results of DNR/SHL water quality monitoring at TMDL station NuCr1 from June 2006 to 2007 suggest “full support” of the Class B(WW2) aquatic life uses. None of the 13 samples collected violated the Class B(WW2) criteria for dissolved oxygen, pH or ammonia.

This assessment is also based on biological data collected in 2009 and 2010 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 biocriteria sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species that were 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 66 (good) and the BMIBI score was 74 (good). The 2010 FIBI score was 65 (good) and the BMIBI score was 77 (excellent). 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 biological impairment criteria were determined 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 segment passed the FIBI and BMIBI BICs 2/2times in the last eight years.

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 years in the most recent five year period (2012-2016) to be considered “monitored”. This segment had multiple samples collected in the previous eight years (2009-2016).Also, 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).