Des Moines River IA 04-LDM-1011
from Ottumwa dam (S24 T72N R14W Wapello Co.) to confluence with Cedar Cr in S33 T75N R17W Mahaska Co.
The Class A1 use was assessed as “fully supported” based on water quality monitoring data. The Class BWW1 use was assessed as "WINOFI” based on the results of a fish kill investigation. The Class C use was assessed as "fully supported" based on water quality monitoring data and drinking water compliance monitoring required by the DNR. All other designated uses were "not assessed." Note: The Site ID for the data tables in the Assessment Explanation sections Class A1, BWW1, and Class C have all been updated to Site ID 10900003. From 2020 IR to 2024 IR, DNR inadvertently put Site IDs 10900002 and 10620001 in the data tables. The results for Site ID #10900003 were correctly assessed in the data tables for this segment from 2020-2024; however, the sites in the site ID column were incorrect. This update occurred on 10-5-2026.
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description Iowa DNR 6 WQ CY 2012-2014 10900003 Des Moines River US of Ottumwa at Co Rd T67 Bridge at
Chillicothe Iowa DNR 6 BIO See Below 1156 Des Moines River – Chillicothe REMAP #454 Site ID Data Source ID # Samples / # Years 2012 Geometric Mean 2013 Geometric Mean 2014 Geometric Mean Annual Geometric Mean Violation # Violations % Violations Significantly >10% Violations Assessment Type Support Level 10900003 6 22 / 3 86 40 100 No 3 14% No Evaluated Full Site ID Data Source ID # Samples / # Years Maximum Value Mean Value Median Value # Violations % Violations Significantly >10% Violations Assessment Type Support Level 10900003 6 33 / 3 8.7 8.2 8.2 0 0% No Evaluated Full Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value # Acute / Chronic Violations % Acute/ Chronic Violations Significantly >10% Violations Assessment Type Support Level 10900003 6 Ammonia 33 / 3 0.45 0.1 0.05 0 / 0 0% / 0% No Evaluated Full 10900003 6 Chloride 33 / 3 91 49 43 0 / 0 0% / 0% No Evaluated Full 10900003 6 Dissolved oxygen 33 / 3 17 10.6 10.1 NA / 0 NA / 0% No Evaluated Full 10900003 6 pH 33 / 3 8.7 8.2 8.2 0 / NA 0% / NA No Evaluated Full 10900003 6 Sulfate 33 / 3 130 78 82 0 / NA 0% / NA No Evaluated Full 10900003 6 Temperature 33 / 3 29.1 12.8 11.8 0 / 0 0% / 0% No Evaluated Full BioNet Site ID Date Drainage Area (mi2) Ecoregion Major Drainage/Thermal BM Sample Gear BMIBI score BMIBI Class BMIBI BIT BMIBI Pass/Fail 1156 8/22/17 13200 40a MS/WW Float ArtSub 64 Good 41 Pass BioNet Site ID Date Drainage Area (mi2) Ecoregion Major Drainage/Thermal Riffle Stream? FIBI score FIBI Class 40a FIBI BIT FIBI Pass/Fail 1156 8/22/17 13200 40a MS/WW NA 32 Fair 33 Pass Community Assessment Type Assessment Result Support Level IR Category Reason Benthic Macroinvertebrates Evaluated Pass (1/1) Full FIBI
passed using the 7 point FIBI UAV applied to single samples. Fish Evaluated Pass (1/1) Full Assessment was evaluated because the drainage area of
the Overall Evaluated Pass Full 1 sample site was larger than the calibrated range. The Class BWW1 use
assessment based on the 2017 fish kill placed this segment in Category 3b.
Because the cause of the fish kill was not identified, or the fish kill was
attributed to a non-pollutant cause (e.g., winterkill), the assessment type is
“evaluated.” Segments assessed using “evaluated” assessments are placed in
Category 3b and are added to the state list of waters in need of further
investigation. If no additional fish kills are reported in the segment for a
5-year period (2022), the Category will be changed from 3b to 3a (water not
assessed). Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value # Violations % Violations Significantly >10% Violations Assessment Type Support Level 10900003 6 Chloride 33 / 3 91 49 43 0 0% No Evaluated Full 10900003 6 Inorganic nitrogen (nitrate and nitrite) 33 / 3 14 4 3.4 2 6% No Evaluated Full Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value Number of Non - Detects Mean Value > Criterion or MCL Assessment Type Support Level 10900003 6 Alachlor 32 / 3 0.1 0.04 0.025 NA No Evaluated Full 10900003 6 Atrazine 26 / 3 2 0.43 0.2 NA No Evaluated Full 10900003 6 Carbofuran 26 / 3 0.1 0.1 0.1 NA No Evaluated Full 10900003 6 Cyanazine 26 / 3 0.1 0.1 0.1 NA No Evaluated Full Compliance monitoring
required by the Iowa DNR Water Supply Operations and Engineering Sections did
not show violations of finished water that were caused by source water at the
Ottumwa Water Works facility during the 2020-22 monitoring period. The violations
reported were related to plant operations (failure to monitor).The results of
compliance monitoring as reported in annual compliance reports are available at
the following location at the Iowa DNR’s home page: https://www.iowadnr.gov/Environmental-Protection/Water-Quality/Water-Supply-Engineering/Annual-Compliance-Report.
Class
A1 - Indicator Bacteria:
Class
A1 - pH:
Class
BWW1 - Binomial Parameters:
Class
BWW1 - Biological Sampling:
Benthic Macroinvertebrates:
Fish:
Overall:
Class
BWW1 – Fishkill Assessment:
Details about the 2017 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/944
Class
C - Binomial Parameters:
Class
C - Toxic Parameters:
Class
C - Iowa Drinking Water Compliance Report:
Class HH - No Data