Missouri River IA 06-WEM-1721
from confluence with Elm Cr. (S18 T83N R46W Monona Co. at river mile 691.0 at Decatur NE.) to confluence with Omaha Creek Ditch east of Homer NE at river mile 715.8 (=SW 1/4 S6 T86N R47W Woodbury Co. (near Browns Lake)).
- Cycle
- 2024
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 11/1/2023 8:13:45 AM
- Updated
- 1/17/2024 7:47:47 AM
The 2020-2022 E. coli data suggest full support of the Class A1 use; however, delisting an impairment requires a monitored assessment. Therefore, the Category 5a Class A1 impairment will remain. The Class BWW1 use remains assessed as "not supported" based on information from local fisheries biologists on impacts related to flow modification and habitat alterations in this segment of the Missouri River. All other designated uses were "not assessed."
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description USACE 12 WQ CY 2020-2022 99990120 Missouri
River
Class A1 - Indicator Bacteria: Site ID Data Source ID # Samples per Year (2020/ 2021/2022) 2020 Geometric Mean 2021 Geometric Mean 2022 Geometric Mean Violates Annual Geometric Mean? # 2020 SSM violations / SSM Violations needed for impairment # 2021 SSM violations / SSM Violations needed for impairment # 2022 SSM violations / SSM Violations needed for impairment Violates Annual SSM Significantly >10% Rule? Assessment Type Support Level 99990120 12 7/8/7 23 12 19 NO 1 / 3 0 / 3 0 / 3 NO Eval Full The 2020-2022 E. coli data suggest full support of the Class A1 use; however, delisting an impairment requires a monitored assessment. Therefore, the Category 5a Class A1 impairment will remain. Class A1 - pH: Site ID Data Source ID # Samples / # Years Minimum Value Maximum Value Mean Value # Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 99990120 12 34 / 3 7.54 8.78 8.07 0 7 NO Mon Full Class BWW1 - Binomial Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Mean Value # Violations # Acute / Chronic Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 99990120 12 Chloride 36 / 3 13 22 16 NA 0 / 0 7 NO Mon Full 99990120 12 Dissolved Oxygen 35 / 3 7.29 14.25 10.78 0 NA / NA 7 NO Mon Full 99990120 12 pH 34 / 3 7.54 8.78 8.07 0 NA / NA 7 NO Mon Full 99990120 12 Sulfate 36 / 3 216 300 253 0 NA / NA 7 NO Mon Full 99990120 12 Temperature 35 / 3 -0.03 27.12 11.64 0 NA / NA 7 NO Mon Full Class BWW1 - Toxic Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value # Acute / Chronic Violations >1 Acute / Chronic Violation Assessment Type Support Level 99990120 12 Ammonia 34 / 3 0.26 0.06 0.04 0 / 0 NO Mon Full 99990120 12 Selenium 12 / 3 5 3 2 0 / 0 NO Mon Full Class BWW1: Historical Assessment The Class BWW1 aquatic life use remains assessed as "not
supported" (IR Category 4c, non-pollutant stressor) based on the
assessment developed for the 1998, 2000, and 2002 reports (i.e., habitat
alterations and flow modifications that resulted from development of the river
for navigation uses in the mid-Twentieth Century). This assessment was
developed in consultation with the Missouri River fisheries biologist for the
state of Nebraska. Class HH-F - Toxic Parameters: Site ID Data Source ID Parameter Name # Samples per Year (2020/ 2021/2022) 2020 Mean 2021 Mean 2022 Mean # Non-Detects per Year (2020/ 2021/2022) Support Level per Year (2020/ 2021/2022) Assessment Type Support Level 99990120 12 Mercury 4/4/4 0.003 0.028 0.003 3/2/3 Full/Full/Full Mon Full 99990120 12 Selenium 4/4/4 3.25 2.5 2.25 0/0/0 Full/Full/Full Mon Full