Indian Creek IA 02-CED-505

Assessment Comments

Assessment is based on results of ambient water quality monitoring conducted in summer 2002 as part of the Cedar Rapids intensive urban monitoring project.

Basis for Assessment

[Note:  For the 2002 report, data that was collected in the upstream waterbody segment of Indian Creek (IA 02-CED-0211-0) was erroneously used to assess this segment.   For the 2004 reporting cycle, that assessment can now be found in waterbody segment IA 02-CED-0211-0.]

SUMMARY:  The Class B(LR) aquatic life uses are assessed (monitored) as “fully supported” based on results of ambient water quality monitoring conducted near Marion in summer 2002 as part of the Cedar Rapids intensive urban monitoring project.

EXPLANATION:  Results of ambient water quality monitoring conducted in summer 2002 for the Cedar Rapids intensive urban monitoring project indicate good chemical water quality in this stream segment.   The purpose of this project is to measure the daily variability of water quality through time in two urban streams in the Cedar Rapids area:  McCloud Run and Indian Creek.   Both streams are monitored by the City of Cedar Rapids Water Pollution Control as part of their storm water monitoring program.   The daily monitoring is designed to supplement the storm water monitoring being conducted on these two streams by the City of Cedar Rapids.   In 2002, sampling was conducted daily on Indian Creek from about mid-May to mid August.   Parameters monitored include pesticides, toxic organics, conventional parameters (including nutrients), and bacterial indicators (e.g., fecal coliforms and E.  coli).   In general—and in the context of the aquatic life uses designated for this stream—results of this monitoring show good water quality.   The vast majority of the approximately 80 samples collected in summer 2002 did not violate the respective Class B(LR) aquatic life criteria for dissolved oxygen, pH, or ammonia nitrogen.  

One of 84 samples violated the Class B(LR) criterion for dissolved oxygen:  the sample collected on August 13, 2002 contained 4.7 mg/l of dissolved oxygen, thus violating the Class B(LR) criterion of 5.0 mg/l.   Two of 84 samples violated Class B(LR) criteria for pH:  samples collected on July 2 and August 13 had pH readings of 6.46 and 5.98 units, respectively.   According to U.S.  EPA guidelines for Section 305(b) water quality assessments (U.S.  EPA 1997b, page 3-17), the percentages of violations for dissolved oxygen (1%) and pH (2%) at this station do not suggest a water quality impairment (the EPA guidelines allow up to 10% violations of these conventional parameters before impairment of water quality is indicated).   Metals, pesticides, and other toxic organics were sampled on only three days during summer 2002:  May 30, June 6 and June 8.   None of the results even approached the respective Class B(LR) aquatic life criteria.