Assessment Comments
Assessment remains based on results of biological monitoring conducted in 2005 as part of the IDNR/UHL stream biocriteria project, and results of ambient monthly water quality monitoring conducted by IDNR/UHL at two locations on Camp Creek from March to November 2003 as part of monitoring in support of TMDL development: (1) approximately 3 miles SE of Runnells (lower site--STORET station 11770001) and (2) 1.5 miles downstream from Mitchell Park (upper site--STORET station 11770002).
Basis for Assessment
[Note 1: Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(LR) aquatic life uses. Due to changes in Iowa’s surface water classification that were approved by U.S. EPA in February 2008 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf), this segment is now presumptively designated for Class A1 (primary contact recreation) uses. The stream remains designated for aquatic life uses (now termed Class B(WW2) aquatic life uses). Thus, for the current (2010) assessment, the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW2) water quality criteria.]
[Note 2: A TMDL for siltation and nutrients in this segment of Camp Creek was prepared by IDNR and approved by EPA in 2005. Because the Section 303(d) impairments identified for the 2006 assessment/listing cycle are believed addressed by the TMDL, this waterbody is placed into IR Category 4a (impaired; TMDL approved).]
[Note 3: Although IDNR/UHL monitoring was conducted in this segment during the 2004-2006 assessment period, only three samples were collected and analyzed. As were previous data, these samples were collected at IDNR/UHL TMDL stations 11770001 and 11770002. In addition, a sample was collected at IDNR/UHL TMDL station 11770005 near Mitchellville. None of the three samples violated the respective Class B(WW2) criteria for ammonia, dissolved oxygen, or pH. This amount of data is insufficient for developing an updated assessment of support of designated uses. Thus, the assessment developed for the previous (2006) assessment cycle was used for the 2008 cycle and will again be used for the 2010 cycle.]
SUMMARY: The presumptive Class A1 (primary contact recreation) uses remain “not assessed” due to the lack of information upon which to base an assessment. IDNR/UHL TMDL monitoring conducted from March 2001 through July 2005 did not include analysis for indicator bacteria. The Class B(WW2) aquatic life uses remain assessed (monitored) as "partially supported" based on results of biological monitoring conducted in 2005 as part of the IDNR/UHL stream biocriteria project. Sources of data for this assessment also include the results of ambient monthly water quality monitoring conducted by IDNR/UHL at two locations on Camp Creek from March to November 2003 as part of monitoring in support of TMDL development: (1) approximately 3 miles SE of Runnells (lower site--STORET station 11770001) and (2) 1.5 miles downstream from Mitchell Park (upper site--STORET station 11770002).
EXPLANATION: The presumptive Class A1 (primary contact recreation) uses remain not assessed due to the lack of information upon which to base an assessment. The previous assessment of support for the Class B(WW2) aquatic life uses of this stream ("partially supported") was based on the results of IDNR biological monitoring in November 1990 that suggested lower than expected diversity of aquatic life in this stream segment (see assessment developed for the 1998 report). Results of follow-up biological and chemical monitoring conducted during the 2000-2001 biennial period suggested that, despite relatively good chemical water quality, the status of the biological community continued to suggest an impairment of the Class B(WW2) aquatic life uses.
Results of TMDL-related (chemical) monitoring in 2001 suggest that Camp Creek had relatively good water quality: none of the nine samples collected between March and November 2001 violated the Class B(WW2) chronic water quality criterion for dissolved oxygen, pH, or ammonia nitrogen. The samples collected on March 7, 2001 at both sites, however, had relatively high levels of ammonia-nitrogen: the sample from the upper site contained 1.2 mg/l, and the sample from the lower site contained 1.8 mg/l of ammonia-nitrogen. Although these levels did not exceed the Class B(WW2) chronic criteria for ammonia-nitrogen, they were nonetheless atypically high for ambient conditions in Iowa’s streams and rivers.
Results of monitoring from March to November 2003 showed no violations of Class B(WW2) criteria for ammonia, dissolved oxygen, pH or temperature in the 16 samples collected at the lower (Runnells) site and in the eight samples collected at the upper (Mitchellville) site. Maximum levels of ammonia continued to appear relatively high, with maximum values of 2.7 mg/l at the Runnells site and 1.5 mg/l at the Mitchellville site during 2003; these levels, however, did not violate the Class B(WW2) chronic criteria for ammonia.
Results of biological monitoring conducted in 2005 as part of Section 305(b) follow-up activities suggested "partial support" of the Class B(WW2) uses. 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 2005 FIBI scores from the lower two TMDL sites located in the 47f ecoregion were 25 (poor), 39 (fair) and the BMIBI scores were 76 (excellent), 76 (excellent). The 47f FIBI BIC is 36 and the 47f BMIBI BIC is 51. The upper biological sampling site is located in Thomas Mitchell County Park and is in the 47b ecoregion. The upper site 2005 FIBI score was 30 (fair) and the BMIBI score was 74 (good). The 47b riffle habitat FIBI BIC is 53 and the 47b BMIBI BIC is 62. The aquatic life use support was assessed as partially supporting (=PS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports. This segment passed the FIBI BICs 1/3 times and passed the BMBIBI BICs 3/3 times in 2005. The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004.
