The Class A1 uses are assessed (monitored) as “partially supported” due to violations of Iowa’s water quality criteria for indicator bacteria (E. coli) during the previous (2010-2012) monitoring period.  Results of bacteria monitoring during the current (2012-2014) monitoring period, however, do not suggest impairment of the Class A1 uses.  The geometric means of indicator bacteria (E. coli) in the 29 samples collected during the recreational seasons of 2010 through 2012 at USGS station 05490500 at Keosauqua were as follows:  the 2012 geometric mean was 30 orgs/100 ml, the 2013 geometric mean was 75 orgs/100 ml, and the 2014 geometric mean was 66 orgs/100 ml.  None of the geometric means exceeded the Class A1 criterion of 126 orgs/100 ml.  Five of the 27 samples (19%) exceeded the Class A1 single-sample maximum criterion of 235 orgs/100 ml.  According to the Iowa DNR assessment/listing methodology, the frequency of violation of this single-sample criterion is not significantly greater than 10%.

Too few samples were analyzed for indicator bacteria at Iowa DNR station 10890001 to calculate a geometric mean appropriate for comparison to Iowa’s Class A1 geometric mean criterion of 126 orgs/100 ml.  The Iowa DNR assessment/listing methodology requires that geometric means be based on at least seven E. coli samples per recreation season in order to support a Section 303(d) listing.  Only four samples were analyzed for indicator bacteria at station 10890001 during the recreation season of 2012, and only two samples were collected during the 2014 season.  Regardless, the geometric means based on these few Iowa DNR samples are consistent with the USGS geometric means.  The 2012 recreation season geometric mean at DNR station 10890001 was 91 org/100 ml, and the 2014 geometric mean was 27 orgs/100 ml.  Both geometric means are well-below (meet) the Class A1 criterion of 126 orgs/100 ml.  None of the six samples collected by Iowa DNR exceeded the Class A1 single-sample maximum criterion of 235 orgs/100 ml.  According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if all recreation season geometric means are below (meet) respective water quality criterion, and if the frequency of violation of Iowa’s single-sample maximum criterion is not significantly greater than 10%, the contact recreation uses should be assessed as “fully supporting".  Because, however, the IDNR assessment/listing methodology requires that, before a Section 303(d0 bacterial impairment can be de-listed, geometric mean levels of E. coli must all be less than the applicable state water quality criteria for two consecutive listing cycles (i.e., five consecutive years), the existing impairment of the Class A1 uses will remain in effect.  Nonetheless, current and historical monitoring suggest very low levels of indicator bacteria in this river segment. 

The Class B(WW1) aquatic life uses remain assessed (monitored) as “partially supported” (IR 5b) due to fish kills on July 31, 2002, July 10, 2006, and on July 7, 2012 on the reach of river between Eldon (Wapello Co.) and Douds (Van Buren Co.).  These kills are three in a series of kills that have occurred over the last 15 years or so that appear to involve primarily shovelnose sturgeon (Scaphirhynchus platorynchus).  Although the cause of the three recent kills and the previous kills remains unknown, the leading hypotheses are (1) that very high water temperatures, very low river flows, and elevated pH levels combine to make ambient levels of ammonia in the river toxic to the ammonia-intolerant shovelnose sturgeon and (2) that the kills are caused by a virus specific to shovelnose sturgeon.  The most recent kill in July 2012 was especially severe.  According to the local IDNR Fisheries biologist, the kill was reported on the lower Des Moines River on July 7, 2012, from approximately Eldon (downriver from Ottumwa) to Farmington in Van Buren County.  An estimated 57,000 fish were killed including at least 35,000 shovelnose sturgeon.  No specific cause of the kill was identified, but low flow conditions, flow alterations, and very high water temperatures (95+F) are believed to have contributed to the kill. 

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(WW1) aquatic life uses of this river reach were assessed as "partially supported” (303(d) impaired).  Also, according to IDNR’s assessment methodology, if a cause of a fishkill was not identified during the IDNR investigation (cause = "unknown"), or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated.”  Such assessments, although suitable for Section 305(b) reporting, typically lack the degree of confidence to support addition to the state Section 303(d) list of impaired waters (Category 5 of the Integrated Report).  Waterbodies affected by such fish kills at usually placed in IR subcategories 2b or 3b and are added to the state’s list of “waters in need of further investigation”.  Due however to (1) the repeated occurrence of these kills over the last 15 years in Wapello and Van Buren counties, (2) the often large numbers of sturgeon killed (thousands), (3) the likelihood that these kills are caused by a pollutant and (4) the possibility that the kills have extended further downstream (possibly to Bonaparte), this impairment was added to Iowa’s 2008 Section 303(d) list (Category 5 of the Integrated Report).  This assessment is also applied to upriver segments (e.g., IA 04-LDM-0010_4).   

Despite the repeated occurrence of sometimes severe fish kills, results of water quality monitoring by the U.S.  Geological Survey and Iowa DNR near Keosauqua from 2012 through 2014 suggest "full support" of the Class B(WW1) uses.  No violations of Class B(WW1) water quality criteria for dissolved oxygen, ammonia, temperature, chloride, or sulfate occurred in the 48 samples analyzed USGS or the nine samples analyzed by Iowa DNR during the 2012-2014 period.  Three of the 48 samples collected by USGS (6%), and one of the nine samples collected by IDNR (11%) exceeded the Class A, B(WW1) criterion for pH.  According to U.S. EPA guidelines for Section 305(b) reporting, if more than 10% of samples exceed state criteria for conventional parameters such as pH, the aquatic life uses should be assessed as "impaired" (see pgs 3-33 to 3-35of U.S. EPA 1997b).  According to IDNR’s assessment/listing methodology, however, the results from USGS station 05490500 and Iowa DNR station 10890001 do not indicate that significantly greater than 10% of the samples exceed either the Class B(WW1) criteria for pH.  Thus, these results do not suggest impairment of the Class B(WW1) aquatic life uses.  In addition, none of the samples analyzed by USGS for arsenic (47 samples), chlorpyrifos (21 samples), dieldrin (21 samples), or selenium (46 samples) exceeded their respective Class B(WW1) aquatic life criteria.  Taken together, these results suggest “full support” of the Class B(WW1) aquatic life uses.  Due, however, to the repeated occurrence of fish kills in this river segment, the Class B(WW1) aquatic life uses remain assessed as “not supporting” (IR 5b). 

Fish consumption/human-health uses are assessed (monitored) as "fully supported" based on (1) results of EPA/IDNR or IDNR fish tissue (RAFT) sampling on the Des Moines River NNW of Keosauqua and (2) results of analysis for pesticides and metals in water.  This site has been sampled for whole-fish common carp since 1994 on an every-other-year basis as part of RAFT trend monitoring.  The 2008, 2012 and 2014 whole-fish samples of common carp had generally low levels of the primary contaminants.  The 2008 sample contained the following: mercury: 0.102 ppm; total PCBs: 0.187 ppm; and technical chlordane: 0.0833 ppm.  The 2012 sample contained the following:  mercury: 0.111 ppm; total PCBs: 0.24 ppm; and technical chlordane: 0.11 ppm.  And the 2014 sample contained the following:  mercury: 0.04 ppm; total PCBs: <0.39 ppm; and technical chlordane: <0.1 ppm.  With the exception of the level of PCBs in the 2012 sample of whole-fish common carp, all levels of these contaminants are below Iowa’s consumption advisory thresholds.  The level of total PCBs in the 2012 sample of whole-fish common carp (0.24 ppm), however, exceeded the 1 meal/week consumption advisory trigger level (0.2 ppm) as defined in Iowa’s fish consumption advisory protocol.  According to the IDNR/IDPH advisory protocol, two consecutive samplings that show contaminant levels are above the trigger level in fillet samples are needed to justify issuance of an advisory.  Also, according to the IDNR/IDPH advisory protocol, the previous results for levels of PCBs in whole-fish samples from the Des Moines River do not warrant issuance of an advisory but do indicate the need to conduct additional monitoring to better define contaminant levels in fillet samples from this river segment.  Follow-up (fillet) monitoring is needed to better determine (1) levels of PCBs in the edible portions (fillets) of fish in this river segment and (2) whether a consumption advisory for PCBs needs to be issued.  The high non-detect level of PCBs in the 2014 whole-fish Common Carp sample (<0.39 ppm) was due to analytical detection levels of 0.13 ppm for each of the three Aroclors (1248, 1254, and 1260) that comprise “total PCBs”. 

None of the samples analyzed from 2012 to 2014 by USGS exceeded their respective HH (human health-fish) criteria for arsenic (47 samples), DDE (six samples), dieldrin (21 samples), and selenium (46 samples).