Assessment Comments
Assessment is based on results of (1) IDNR/UHL monthly ambient monitoring 1 mile N of St. Joseph, Kossuth Co. from 2000-02 and (2) an IDNR investigation of a fish kill in December 2001.
Basis for Assessment
SUMMARY: The Class A (primary contact recreation) uses are assessed (monitored) as "partially supported" due to high levels of indicator bacteria. The Class B(WW) aquatic life uses are assessed (monitored) as "partially supported" due to a fish kill in December 2001. Support of fish consumption uses remains "not assessed" due to the lack of fish contaminant monitoring in this river reach. The sources of data for this assessment include (1) results from the IDNR ambient monthly monitoring station near St. Joseph in Kossuth County (STORET station 10550001) from 2000 through 2002 and (2) occurrence of a fish kill in this river segment in December 2001. Because the party responsible for the 2001 fish kill was identified, and restitution for the kill was sought, this impairment is not considered appropriate for Section 303(d) listing. The impairment due to high levels of indicator bacteria, however, meet requirements for addition of this river segment to Iowa's Section 303(d) list.
EXPLANATION: The Class A uses were assessed (monitored) as "partially supported" based on results of monitoring for indicator bacteria (fecal coliforms). For purposes of Section 305(b) assessments, DNR uses the long-term average monthly flow plus one standard deviation of this average to identify river flows that are materially affected by surface runoff. According to the Iowa Water Quality Standards (IAC 1990:8), the water quality criterion for fecal coliform bacteria (200 orgs/100 ml) does not apply "when the waters are materially affected by surface runoff." Eighteen of the 21 samples collected from the St. Joseph station during the 2000, 2001, and 2002 recreational seasons were collected at flows not materially affected by surface runoff. The geometric mean level of indicator bacteria (fecal coliforms) in these 18 non-runoff-affected samples (142 orgs/100ml) is below the Iowa Class A water quality criterion of 200 orgs/100ml. However, five of the 18 samples (28%) exceeded the U.S. EPA-recommended single-sample maximum value of 400 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting, if more than 10% of the samples exceed the single-sample maximum value of 400 orgs/100 ml, the primary contact recreation uses are "partially supported" (see pgs 3-33 to 3-35of U.S. EPA 1997b).
The Class B(WW) uses are assessed (monitored) as "partially supported." Results of monitoring at the St. Joseph station during the 2000-2002 assessment period show no violations of Class B(WW) (aquatic life) water quality criteria in the 36 samples analyzed for dissolved oxygen, pH, and ammonia or in the nine samples analyzed for pesticides. These results suggest that the aquatic life uses of this river segment are "fully supported." The occurrence of a fish kill during the most recent three years, however, suggests that the Class B(WW) are only "partially supported." This kill occurred in mid-December 2001. The kill began in Lotts Creek northeast of Whittemore in southwestern Kossuth County; the kill resulted from nitrogen fertilizer discharged from a damaged pipeline. The kill included a 31-mile reach of Lotts Creek and an 18.5-mile reach of the East Fork Des Moines River from its confluence with Lotts Creek downstream to Dakota City in Humboldt Co. According to IDNR's assessment methodology for Section 305(b) reporting, occurrence of a single pollution-caused fish kill within the most recent three-year period indicates that the aquatic life uses of a waterbody are only "partially supported." Thus, the Class B(WW) aquatic life uses of this river reach were assessed as "partially supported."
Fish consumption uses remain "not assessed" due to the lack of recent fish contaminant monitoring in this river segment (see assessment developed for the 2000 report above).
