Silver Lake IA 01-MAQ-17
Delaware County S16T88NR4W SE edge of Delhi.
- Cycle
- 2020
- Release Status
- Final
- Overall IR
- 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
- Trophic
- Eutrophic
- Trend
- Stable
- Created
- 7/7/2020 5:13:01 PM
- Updated
- 10/9/2020 2:01:56 PM
The Class A1 use is assessed as “not supported” due to violations of Iowa's water quality criterion for pH. The Class BLW use is assessed as “not supported” due to violations of water quality criteria for pH and Dissolved Oxygen. Class HH use remains assessed (monitored) as “fully supported”. Note: A TMDL for siltation and organic enrichment at Silver Lake was prepared by DNR and approved by EPA in 2002 and an additional TMDL for algae, pH, turbidity and ammonia was completed in 2008 and approved by EPA in 2009. The pH impairment is covered under the 2009 TMDL and the organic enrichment dissolved oxygen impairment is covered under the 2002 TMDL, thus, this waterbody is placed into IR Category 4a (TMDL approved) for the 2020 assessment/listing cycle.
Sources of
Data: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description Iowa DNR 6 WQ CY 2014-2018 22280001 Silver Lake Max Depth
Iowa DNR
FT See Below 199 Silver Lake
Class A1 -
Indicator Bacteria: No Data 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 22280001 6 15 / 5 9.7 8.4 8.2 4 27% YES Monitored Not 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 22280001 6 Chlorophyll a TSI 15 / 5 36 82 58 NO Monitored Full 22280001 6 Secchi TSI 15 / 5 49 77 60 NO Monitored Full 22280001 6 Total Phosphorus TSI 15 / 5 58 90 77 NA NA NA 22280001 6 Inorganic suspended solids 15 / 5 0.3 9.74 2 NA NA NA Class BLW -
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 22280001 6 Ammonia 15 / 5 0.309 0.06 0.02 0 / 0 0% / 0% NO Monitored Full 22280001 6 Dissolved oxygen 15 / 5 12.8 6.7 6.7 NA / 4 NA / 27% YES Monitored Not 22280001 6 pH 15 / 5 9.7 8.4 8.2 4 / NA 27% / NA YES Monitored Not 22280001 6 Temperature 15 / 5 27.1 23.4 22.6 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 22280001 6 11 146.973 99.3 % 0.511 24.2 % NO Evaluated NA Class BLW - Fish Kill: The Class BLW uses that were assessed (evaluated) as "partially supporting" due to a fish kills in 2007 that has been removed based on the assessment methodology. The 3b impairment is switched to 3a "not assessed" based on the age of the non-pollutant caused fish kill. Class HH -
Fish Tissue Sampling:
Site ID Date Species Name Biopart # in sample chlordane result chlordane violation? PCBs result PCBs violation? Hg result Hg violation? Assessment Type Support Level 199 8/19/15 largemouth bass plug 5
0.050 No Monitored Full