Assessment Comments

Assessment is based on results from DNR monthly monitoring station near Elkport, Clayton County and DNR monitoring conducted in support of TMDL development.

Basis for Assessment

SUMMARY:  Class A (primary contact recreation) uses were assessed as "not supported."  The Class B(WW) aquatic life uses were assessed as "fully supported."  Fish consumption uses remain "not assessed."  Sources of data for these assessments include results of (1) IDNR monthly fixed station monitoring near Elkport and (2) IDNR/UHL monthly monitoring conducted from March to November, 2001, near Mederville (Site 33) and Littleport (32) in support of TMDL development for this river reach.   EXPLANATION:  The assessments of support of beneficial uses are based on results of DNR monthly water quality monitoring conducted on the Volga River near Elkport during biennial period from October 1999 through September 2001.   The Class A (primary contact recreation) uses were again assessed as "not supported."  Of the 19 samples from this station analyzed for indicator bacteria (fecal coliforms) during recreational seasons of 2000 and 2001, two samples were collected during conditions of high river flow.   These high flows resulted in monitoring at river discharges that exceeded the long-term monthly average flow plus one standard deviation of this average (flow statistics from Fischer et al.  1990 and Fischer and Eash 1998).   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."  The geometric mean of fecal coliform bacteria in the 17 non-runoff-affected samples was 975 orgs/100 ml, with 12 samples (71%) exceeding the EPA-recommended single-sample maximum value of 400 orgs/100 ml.   The geometric mean (975 orgs/100 ml) is nearly five times the state water quality criterion of 200 orgs/100 ml.   According to U.S.  EPA guidelines for Section 305(b) reporting, if the geometric mean is greater than 200 orgs/100 ml., the primary contact recreation uses are "not supported" (see pgs 3-33 to 3-35of U.S.  EPA 1997b).   This river reach has a history of high levels of indicator bacteria, with assessments of either "partial support" or "nonsupport" of the Class A uses made since the 1992 report (see above).   Results of IDNR monitoring conducted in 2001 in support of TMDL development for this river reach are consistent with this assessment.   The 2001 seasonal geometric mean of the six non-flow affected samples from near Mederville was 294 orgs/100 ml; the geometric mean of the six non-flow affected samples from near Littleport was 264 orgs/100 ml.   Both these geometric means suggest nonsupport of the Class A uses.   The source of the high levels remains unknown.   Additional TMDL-related monitoring was conducted in 2001 on the following Volga River tributaries in river reach:  Bear Creek near Elkport (Site 37) and Doe and Honey creeks near Littleport (Sites 38 and 39, respectively).   Results of this monitoring show extremely high levels of fecal coliform bacteria in these tributaries, with the 2001 recreational season geometric means as follows (N=7; stream flows not evaluated for effects of runoff):  Bear Creek near Elkport:  698 orgs/100 ml; Doe Creek near Littleport:  5,055 orgs/100 ml; Honey Creek near Littleport:  1,465 orgs/100 ml.   Further investigation is needed to determine (1) whether these high fecal levels in these and other tributaries are influencing levels in the Volga River and (2) the sources of the high fecal levels in these tributaries.   The Class B(WW) aquatic life uses were assessed as "fully supported" due to the lack of violations of state water quality criteria for pH, dissolved oxygen, and ammonia-nitrogen in the 29 samples during the current biennial period.   In addition, no violations of Class B(WW) chronic criteria occurred in the four samples analyzed for toxic metals during the biennial period.   Results of monitoring conducted in support of TMDL development near Mederville and Littleport are consistent with this assessment:  none of the nine monthly samples from these stations violated state water quality criteria for dissolved oxygen or pH.   The fish consumption uses remain "not assessed" due to the lack of recent fish tissue monitoring in this river reach.