Floyd River IA 06-FLO-1554

The Class B(WW-2) aquatic life uses remain assessed (monitored) as “partially supporting" based results of biological sampling and on repeated occurrence of fish kills in this river segment.   Both of these types of data suggest impairment of the Class B(WW-2) aquatic life uses.  

Biological data were collected in 2003 and 2006 as part of the IDNR/SHL stream biocriteria and REMAP projects.   A series of biological metrics which 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 and fish species 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 2003 FIBI scores were 37 (fair), 18 (poor); and the 2003 BMIBI score was 65 (good).   The 2006 FIBI score was 22 (poor) and the 2006 BMIBI score was 50 (fair).   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 1994-2008.   The FIBI BIC for this ecoregion is 43 and the BMIBI BIC for this ecoregion is 54.   This segment passed the FIBI BIC 0/3 times and passed the BMIBI BIC 1/2 times in the last 12 years.  

This aquatic life assessment is now considered "evaluated" based on a change in the 2010 IDNR assessment methodology.   IDNR now requires a segment have two or more biological samples collected from the segment in multiple years over a recent five-year period to be considered “monitored”.   This segment had multiple samples collected in the previous 12 years; however, the multiple samples were not collected during a recent five-year period.   Also, because these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is considered “evaluated” (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence).   According to IDNR’s assessment/listing methodology, impairments based on “evaluated” assessments are of lesser confidence and are thus not appropriate for Section 303(d) listing (Category 5 of the Integrated Report).   IDNR does, however, consider these impairments as appropriate for listing under either Category 2b or 3b of the Integrated Report (waters potentially impaired and in need of further investigation).   However, despite this change in assessment methodology and type, this waterbody was previously on Iowa’s Section 303(d) list and thus remains on Iowa’s Section 303(d) list of impaired waters (IR Category 5b-t).

The occurrence of repeated fish kills in this segment of the Floyd River strongly suggest impairment of the Class B(WW2) aquatic life uses.   The most recent kill occurred on or before August 4, 2007.   This kill was attributed to runoff from a cattle feedlot that entered an unnamed tributary of the Floyd River after a heavy rainfall event.   No responsible party for the kill was identified.   An estimated 97,108 fish were killed.   The estimated value of these fish was $ 11,660.42.   The kill affected approximately 7.5 miles of the river near Hospers, IA.  

According to IDNR’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.   Thus, this assessment segment will remain in Category 5b of Iowa’s Integrated Report.  

Prior to the 2007 fish kill a kill occurred on September 12, 2003; this kill was attributed to animal wastes from an open feedlot.   An estimated 3,419 fish were killed.   No responsible party for the kill was identified.   An estimated 3,419 fish were killed; no estimate of the value of the fish killed was provided.   Species killed included minnows, suckers, sunfish, and channel catfish.   The kill affected approximately 6.5 miles of river near Hospers, IA, between 360th Street and 410th Street.   The location point for this kill is Section 23 of T96N, R23W, Sioux County.  

Additional fish kills in this river segment occurred on August 8, 2002 at Hospers, January 8, 2002 at Sheldon, September 24, 1998, and May 17, 1997.   Summaries of these additional kills are provided below:

--The May 1997 kill occurred near Sheldon and was caused by an unintentional discharge of animal waste to the river.   The discharge occurred during the lowering of a feedlot lagoon by using irrigation hose and pipe to pump liquid manure from the lagoon to the application site approx.   1 mile away.   A break in the line occurred where the line crossed the Floyd River.   The pumping ceased shortly (2-3 minutes) after the break, with an estimated 900 gallons per minute being pumped.   The total number of fish killed was estimated at 5.   Restitution for this kill was requested and received by DNR.  

--The September 1998 kill occurred on at, and 15 miles downstream from, Sheldon in Sioux County.   Contents of a catchment basin surrounding a tank with 28% nitrogen were pumped into a storm sewer following a rainfall event.   Toxic materials were discharged from the storm sewer to a drainage way one-quarter mile from the Floyd River.   An estimated 408,000 fish were killed over the 15 mile reach affected by the kill.   Restitution for this kill was requested and received by DNR.  

--The kill in January 2002 resulted from discharge of liquid nitrogen from a farmers coop facility in Sheldon.   Ice conditions prevented the use of usual methods to estimate fish loss.   The numbers of fish killed from Sheldon to Alton were estimated based on a previous fish kill evaluation on this same river reach in 1998.   Ammonia readings of greater than 250 ppm were reported.  

--The kill in August 2002 occurred near Hospers.   The kill started near the bridge at 350th Street; approximately 2 miles of river was affected.   An estimated 5,800 fish were killed.   No cause of this kill was identified, although feedlot runoff delivered to the river by recent rains was suspected as the cause.  

According to DNR's assessment methodology for Section 305(b) reporting, occurrence of two or more pollutant-caused kills within the most recent three-year period indicates that the aquatic life uses are "not supported."  The relatively large number and variety of kills in this river segment, centering around the towns of Sheldon and Hospers, suggests ongoing, although potentially unrelated, impairments of the Class B(WW2) aquatic life of this river reach.