Assessment Comments
Assessment based on results of (1) IDNR/UHL biological (biocriteria) monitoring in 1999 and 2001 and (2) IDNR/UHL ambient water quality monitoring conducted in 2001 and 2003 in support of TMDL development.
Basis for Assessment
SUMMARY: The Class B(LR) aquatic life uses were assessed (monitored) as "partially supported" based on results of biological monitoring conducted in 1999 and 2001 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).
Note: A TMDL for siltation and nutrient 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).
EXPLANATION: The previous assessment of support for the general beneficial 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(LR) 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(LR) 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(LR) chronic criteria for ammonia-nitrogen, these levels were nonetheless relatively high, and the level from the lower site did exceed the Class B(WW) chronic criterion for ammonia-nitrogen.
Results of monitoring from March to November 2003 shows no violations of Class B(LR) 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 continue 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(LR) chronic criteria for ammonia.
Results of biological monitoring conducted in 1999 and 2001 as part of Section 305(b) follow-up activities continue to suggest "partial support" of the Class B(LR) 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 1999 and 2001 FIBI scores were 29 (fair), 19 (poor), and 18 (poor) and the BMIBI scores were 78 (excellent), 44 (fair), 57 (good). The FIBI average was 22 and the BMIBI average was 58.3. 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. The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004. The FIBI BIC for this ecoregion is 36 and the BMIBI BIC for this ecoregion is 51.
