McLoud Run IA 02-CED-508

Assessment Comments

Assessment is based on (1) results of investigation of a fish kill caused by urban runoff in 2001 and (2) data from the Cedar Rapids intensive urban monitoring project in summer 2002.

Basis for Assessment

SUMMARY:  The general (aquatic life) uses remained assessed (monitored) as "partially supported" due to the occurrence of a fish kill during the last three years (2000-2002) and the potential for similar kills to occur in the future.   This kill involved temperature-sensitive fish species (trout) and was attributed to elevated water temperatures in runoff from this stream’s urban watershed following summer rains.   Results of ambient water quality monitoring conducted in summer 2002 for the Cedar Rapids intensive urban monitoring project indicate generally good chemical water quality in this stream.

EXPLANATION:  The previous assessment of support for the general beneficial uses of this stream ("partially supporting" the general aquatic life uses) was based on the occurrence of two spill-related fish kills during the 1996-1997 biennial assessment period (see assessment developed for the 1998 and 2000 reporting cycles).   The most recent fish kill, however, occurred on August 2, 2001 and was due to storm water runoff from urban watershed of this stream.   The rainfall event occurred during very warm summer weather, and the relatively warm runoff water raised the temperature of McCloud Run by 19 degrees F in an hour.   Temperature-sensitive species such as the (stocked) rainbow, brown, and brook trout were killed.   According to DNR's assessment methodology for Section 305(b) reporting, occurrence of a single pollution-caused fish kill within the most recent three-year period (1997-1999) indicates that the aquatic life uses of a waterbody are only "partially supported."  Thus, the general aquatic life uses of this stream remain assessed as "partially supported" due thermal impacts from urban runoff.  

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.   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 McCloud Run 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, results of this monitoring show good water quality.   Although classified only for general uses, Iowa water quality criteria for either Class B(LR) or Class B(CW) aquatic life uses were compared to results of monitoring as an indicator of the status of water quality in this stream.   This comparison showed no violations of criteria for pH or ammonia in the 70+ samples collected during summer 2002.   One of 83 samples contained a level of dissolved oxygen below the 7.0 mg/l water quality criterion for Class B(CW) coldwater streams:  the sample collected on June 10, 2002 contained 6.4 mg/l of dissolved oxygen.   Levels of metals, pesticides, and other toxic organic compounds did not exceed chronic aquatic life criteria .   The only such parameter to approach a state criterion was pentachlorophenol (PCP).   Fifteen of the 79 samples analyzed contained detectable levels of PCP; five of these samples were within 1 ug/l of the respective pH-dependent Class B(LR) criterion.   None of the 81 sample analyzed contained detectable levels of either chlordane (detection level = 0 05 ug/l) or any of the seven PCB Aroclors analyzed (including Aroclors 1248, 1254, and 1260) (detection level = 0.5 ug/l).   Both chlordane and PCBs have been found at elevated levels in fish from either McCloud Run or the adjacent Cedar Lake.  

Fish tissue monitoring conducted in June 2001 following a mid-May fish kill showed that fillet samples of stocked trout (ages 1 and 2) contained levels of chlordane above the 0.300 ppm U.S.  FDA action level.   A second fish tissue sampling in July 2001 showed that levels were just below the FDA action level.   In response, the IDNR Fisheries Bureau has issued a no-kill restriction on trout taken from McCloud Run.   For purposes of Section 305(b) assessment, the general aquatic life uses of McCloud Run are considered "threatened" by the pesticide chlordane.