Coralville Reservoir IA 02-IOW-630
Johnson County S22T80NR6W (dam) 3 mi N of Iowa City.
- Cycle
- 2020
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trophic
- Eutrophic
- Trend
- Stable
- Created
- 7/22/2020 2:31:39 PM
- Updated
- 10/14/2020 9:24:34 AM
The Class A1 uses are assessed (monitored) as “partially supported” due to aesthetically objectionable conditions caused by poor water transparency due to inorganic turbidity and due to high levels of indicator bacteria. The Class BWW1 uses are assessed (monitored) as “fully supported.” Class HH uses are assessed (monitored) as "fully supporting" based previous assessments of data conducted as part of the UI/ACOE "Coralville Water Quality Study."
Sources of
Data: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description USACE 12 WQ CY 2014-2018 3333333 Coralville Reservoir - Surface
USACE 12 WQ CY 2016-2018 99990026 Sandy Beach Coralville
USACE 12 WQ CY 2016-2018 99990027 Sugar Bottom Beach (Coralville)
USACE 12 WQ CY 2016-2018 99990028 West Overlook Beach Coralville
Iowa DNR 6 WQ CY 2014-2016 22520004 Coralville Reservoir
Class A1 -
Indicator Bacteria: Site ID Data Source ID # Samples / # Years 2016 Geometric Mean 2017 Geometric Mean 2018 Geometric Mean Annual Geometric Mean Violation # Violations % Violations Significantly >10% Violations Assessment Type Support Level 3333333 12 36 / 3 23.92 13.52 NA NO 0 0% NO Monitored Full 99990026 12 50 / 3 56.14 59.96 165.7 YES 10 20% YES Monitored Partial 99990027 12 49 / 3 19.69 15.19 36.91 NO 2 4% NO Monitored Full 99990028 12 49 / 3 31.35 29.18 36.63 NO 1 2% NO Monitored Full Class A1 - pH Site ID Data Source ID # Samples / # Years Maximum Value Mean Value Median Value # Violations % Violations Significantly >10% Violations Assessment Type Support Level 22520004 6 9 / 3 8.36 8.05 8.1 0 0% NO Evaluated Full 3333333 12 99 / 5 8.86 8.17 8.23 1 1% NO Monitored Full Class A1 - Lake
TSI's Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Median Value Median TSI Violation Assessment Type Support Level 22520004 6 Chlorophyll a TSI 9 / 3 41 63 54 NO Monitored Full 3333333 12 Chlorophyll a TSI 55 / 5 41 81 60 NO Monitored Full 22520004 6 Secchi TSI 9 / 3 62 87 73 YES Monitored Not 3333333 12 Secchi TSI 69 / 4 16 99 78 YES Monitored Not 22520004 6 Total Phosphorus TSI 9 / 3 78 87 82 NA NA NA 3333333 12 Total Phosphorus TSI 86 / 5 63 131 83 NA NA NA 22520004 6 Inorganic suspended solids 9 / 3 7.6 36.5 15.4 NA NA NA Class BWW1 -
Conventional Parameters: 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 22520004 6 Ammonia 9 / 3 0.23825 0.11 0.05 0 / 0 0% / 0% NO Evaluated Full 3333333 12 Ammonia 85 / 5 0.92 0.13 0.06 0 / 0 0% / 0% NO Monitored Full 22520004 6 Dissolved oxygen 9 / 3 10 7.2 6.5 NA / 0 NA / 0% NO Evaluated Full 3333333 12 Dissolved oxygen 99 / 5 23.4 8.5 7.8 NA / 8 NA / 8% NO Monitored Full 22520004 6 pH 9 / 3 8.36 8.05 8.1 0 / NA 0% / NA NO Evaluated Full 3333333 12 pH 99 / 5 8.86 8.17 8.23 1 / NA 1% / NA NO Monitored Full 22520004 6 Temperature 9 / 3 27.8 23.64 24.12 0 / 0 0% / 0% NO Evaluated Full 3333333 12 Temperature 98 / 5 30 18.4 21.2 0 / 0 0% / 0% NO Monitored Full Class BLW -
Lake Planktonic Cyanobacteria: Site ID Data Source ID # Samples Maximum Cyanobacteria Wet Mass Maximum Cyanobacteria % Composition Median Cyanobacteria Wet Mass Median Cyanobacteria % Composition Median Cyanobacteria Wet Mass = 75th
Percentile Assessment Type Support Level 22520004 6 9 13.133 82 % 0.568 6.8 % NO Evaluated NA Class HH -Fish consumption uses are assessed (monitored) as "fully supporting."Fish contaminant monitoring conducted in Coralville Reservoir in 2010 and 2012 as part of the Coralville Reservoir Water Quality Study showed that levels of organochlorine contaminants (chlordane, dieldrin, and heptachlor epoxide) in composite samples of whole-fish carp were very low. The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of the degree to which Iowa’s lakes and rivers support their fish consumption uses. The fish contaminant data generated from the 2010 and 2012 ACOE fish contaminant monitoring conducted at Coralville Reservoir show that the levels of contaminants do not exceed any of the advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody. Monitoring also showed low levels of mercury and PCBs.