Whitewater Creek IA 01-NMQ-103

The Class A1 (primary contact recreation) uses remain assessed (monitored) as “not supported” based on results of DNR bacteria monitoring in 2012 and 2013. The geometric means of indicator bacteria (E. coli ) in the 14 samples collected during the recreational seasons of 2012 and 2013 at station 15310001 were as follows: the 2012 geometric mean was 717 orgs/100 ml, and the 2013 geometric mean was 4,404 orgs/100 ml. Both geometric means exceed the Class A1 criterion of 126 orgs/100 ml. Thirteen of the 14 samples (93%) exceeded the Class A1 single-sample maximum criterion 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 a recreation season geometric mean exceeds the respective water quality criterion, the contact recreation uses are "not supported" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as “impaired.”

The fish kill occurred before September 19, 2016 due to the poor condition of fish carcasses at the time of the investigation. The kill affected approximately 7,821 fish in 23.8 miles of stream(s) in two counties. The fish were valued at $16,503.13 and the investigation expenses were $1,741.04. The following partial information is from the fish kill data base:

Based on the extent of decay it is probable that the fish kill occurred during the previous week. We identified the following 17 fish species dead in the kill area: Bluegill, Bluntnose Minnow, Central Stoneroller, Channel Catfish, Common Shiner, Creek Chub, Fantail Darter, Gizzard Shad, Green Sunfish, Highfin Carpsucker, Hornyhead Chub, Northern Hogsucker, Redhorse (unidentified species), Smallmouth Bass, Spotfin Shiner, Stonecat, White Sucker. This was an extensive fish kill of large magnitude that appeared to have occurred during a period of high stream discharge. It is likely that this was the most significant (numbers of fish, monetary value, and lost recreational value) fish kill that I have investigated during the past 14 years. Valuation and estimates of fish lost are grossly underestimated by this investigation given the extent of fish decay, high stream discharge, and high stream turbidity.

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. If, however, a consent order has been issued to the party responsible for the kill and monetary restitution has been sought for the fish killed, the affected waterbody will be placed in IR Category 4d (impaired but TMDL not required). DNR records indicate that at the time of this assessment, the party responsible for the 2016 kill hasn't been identified nor has DNR sought and has received restitution for the value of the fish killed and the investigation costs incurred. Thus, this assessment segment is appropriate for Category 5b of Iowa’s Integrated Report.

For purposes of Section 303(d) listing, the assessment of the Class B(WW1) aquatic life uses remains based on the percent change in the number of species of freshwater mussels found in the 1984-85 survey versus the 1998-99 survey. For stream segments having four or more species reported for the 1984-95 survey, results of this comparison were used by staff of the Iowa DNR Water Quality Bureau to assess the degree to which the aquatic life uses of the sampled stream segments are supported. Greater than a 50% decline in species richness from the 1984-85 to the 1998-99 period suggests an impairment of the aquatic life uses. Species richness of freshwater mussels at the two sample sites in this segment of Whitewater Creek was 8 and 3, respectively, in the 1984-85 period (average of 5 species) and was zero at both sites in the 1998-99 period for an average percent change of minus 100%. Based on these results, the aquatic life uses are assessed (monitored) as “not supported.” As presented by Arbuckle et al. (2000), the potential causes of declines in species richness of Iowa's freshwater mussels include siltation, destabilization of stream substrate, stream flow instability, and high instream levels of nutrients (phosphorus and nitrogen). Their study also suggested the importance of stream shading provided by riparian vegetation to mussel species richness.

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). Despite this change in assessment type, this waterbody remains in IR Category 5b.

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream segment