McLoud Run IA 02-CED-508

[Note: The previous impairment of this stream was due to fish kills related to high-temperature stormwater from summer precipitation events in the primarily urban watershed of McLoud Run. A TMDL for these thermal impacts was prepared by DNR and approved by U.S. EPA in 2007. Because, however, this TMDL did not address the potential causes of more recent fish kills (e.g., discharge of chlorinated water to the stream), this stream remains Section 303(d)-impaired and in Category 5a of Iowa's Integrated Report.]

The presumptive Class A1 (primary contact recreation) uses remain assessed (monitored) as "not supported" based on levels of indicator bacteria that exceeded state water quality criteria. The geometric means of indicator bacteria (E. coli) in the 12 samples collected during the recreational season of 2010 (889 orgs/100 ml), and the geometric mean of the 11 samples collected during the recreation season of 2011 (1,282 orgs/100 ml) both far exceeded the Class A1 criterion of 126 orgs/100 ml. Twenty-two of the combined 23 samples (96%) 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 is greater than 126 orgs/100 ml., the primary contact recreation uses should be assessed as “impaired” (see pgs 3-33 to 3-35 of U.S. EPA 1997b).

A total of five fish kills occurred in this segment from 1997-2005. For more information on those historic fishkills, see previous IR assessments for this segment for view the fishkills in the Iowa Fishkill Database -https://programs.iowadnr.gov/adbnet/Segments/508

Three additional fishkills have been reported for McLoud Run since 2005. The first kill occurred on October 24, 2012 and resulted from water main break that discharged approximately 2,000 gallons of chlorinated water to storm sewers that discharged to the stream at 32nd Street. An estimated 389 fish were killed over an 0.8-mile reach of stream; the value of the fish killed was estimated at $5,835. The second kill occurred on September 6, 2013, and also resulted from a water main break that discharged approximately 4,500 gallons of chlorinated water into a storm sewer that discharges to the stream. An estimated 143 fish were killed over 0.7 miles of stream with a valuation of $1,516. The third kill occurred on May 16, 2016 and was attributed to an unknown cause. An estimated 319 fish (trout) were killed over 1.6 miles of stream with a valuation of $7,975. Thus, due to these ongoing fish kills, the aquatic life uses of McLoud run will remain assessed as “not supporting” and will remain on Iowa’s Section 303(d) list of impaired waters.

According to DNR’s assessment/listing methodology, the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired”. If a cause of the kill is identified, and the cause is either known, or suspected, to be a “pollutant”, the assessment type is considered “monitored” and the affected waterbody is a candidate for Section 303(d) listing. Fish kills attributed to a pollutant, but where a source of the pollutant was not identified and/or where enforcement actions were not taken against the responsible party, will be placed into Integrated Report subcategory 5b. The intent of placing these waterbodies into Category 5 is not to necessarily require a TMDL but to keep the impairment highlighted due to the potential for similar future kills from the unaddressed causes and/or sources. The three fish kills that have occurred on McLoud Run from 2005 to 2016 were pollutant-related or of unknown cause and justify inclusion on Category 5 of Iowa’s Integrated Report.

Despite the reoccurring fish kills on McLoud Run, the results of the most recent DNR/SHL biological sampling conducted in 2007 suggest that the Class B(WW1) aquatic life uses should be assessed (evaluated) as “fully supporting.” A series of biological metrics that reflect stream water quality and habitat integrity were calculated from the biological sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa collected in the stream sampling reach. The biological metrics were combined to make a benthic macroinvertebrate index (BMIBI). The index ranks the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2007 BMIBI score was 63 (good). The aquatic life use support was assessed (evaluated) as fully supporting (=FS), based on a comparison of the BMIBI score with biological impairment criteria (BIC) established from a statistical analysis of biological data collected at stream ecoregion reference sites from 1994-2008. The natural substrate sampler BMIBI BIC for this ecoregion is 70. This site passed the BMIBI BIC using the uncertainty adjustment value (UAV) of 8 points applied to single sample assessments. Even though this site passed the BMIBI BIC, it is uncertain as to whether or not this segment is meeting the aquatic life criteria because it is a small presumed B-WW1 (formally general use) stream and doesn’t fall in the calibrated watershed size. The assessment of “full support” of aquatic life uses based on biological monitoring may reflect the lack of any known fish kills between 2005 and 2012.

Results of ambient water quality monitoring from May 2010 to July 2011 at STORET station 15570003 also suggest good chemical/physical water quality and “full support” of the Class B(WW2) aquatic life uses. No violations of Class B(WW2) water quality criteria for dissolved oxygen, pH, or temperature occurred in the 23 samples collected at Station 15570003 and analyzed from May 2010 to July 2011.

Fish contaminant monitoring conducted in 2004 suggests a lowering of contaminant levels in fish from McLoud Run. Fish tissue monitoring conducted in June 2001 following a mid-May fish kill showed that fillet samples of stocked rainbow 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 DNR Fisheries Bureau issued a no-kill restriction on trout taken from McLoud Run. Additional fish tissue monitoring was conducted as part of the U.S. EPA/DNR RAFT program in 2004, and results of this monitoring suggested much lower contaminant levels than in samples from 2001. The levels of the primary contaminants in the composite samples of fillets white sucker (Catostomus commersonii) and rainbow trout (Oncorhynchus mykiss) were as follows: white sucker: mercury: 0.085 ppm; total PCBs: 0.091 ppm; and technical chlordane: 0.032 ppm; rainbow trout: mercury: < 0.018 ppm; total PCBs: 0.09 ppm; and technical chlordane: < 0.03 ppm.

The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of support of fish consumption uses in Iowa’s rivers and lakes. Prior to 2006, DNR used action levels published by the U.S Food and Drug Administration to determine whether consumption advisories should be issued for fish caught as part of recreational fishing in Iowa. In an effort to make Iowa’s consumption more compatible with the various protocols used by adjacent states, the Iowa Department of Public Health, in cooperation with Iowa DNR, developed a risk-based advisory protocol. This protocol went into effect in January 2006. Because the revised (2006) protocol is more restrictive than the previous protocol based on FDA action levels; fish contaminant data that previously suggested “full support” may now suggest either a threat to, or impairment of, fish consumption uses. This scenario, however, does not apply to the fish contaminant data generated from the 2004 RAFT sampling conducted in McLoud Run: levels of all contaminants from this monitoring were below the updated advisory trigger levels, thus suggesting the “full support” of fish consumption uses.