Snyder Bend Lake IA 06-WEM-1734
Woodbury County S17T86NR47W 3 mi SW Salix.
- Cycle
- 2020
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 9/1/2020 1:12:14 PM
- Updated
- 10/15/2020 11:08:38 AM
the Class A1 uses of Snyder Bend Lake are assessed (monitored) as "not supported" due to poor water transparency and aesthetically objectionable conditions caused by algae blooms. The Class BLW uses are assessed (monitored) as "fully supported." All other designated uses are “not assessed.”
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 22970003 Snyder Bend Lake Lake Deep Point Iowa DNR
FT See Below 359 Snyder Bend 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 22970003 6 15 / 5 8.9 8.4 8.4 0 0% 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 22970003 6 Chlorophyll a TSI 15 / 5 36 78 64 NO Monitored Full 22970003 6 Secchi TSI 15 / 5 68 83 77 YES Monitored Not 22970003 6 Total Phosphorus TSI 15 / 5 61 80 73 NA NA NA 22970003 6 Inorganic suspended solids 15 / 5 7.66 38.9 18 NA NA NA Although the index value for Chlorophyll a is below the impairment trigger of 65 for this assessment cycle, Snyder Bend Lake was listed as partially supporting its Class A1 uses due to aesthetically objectionable conditions. Based on DNR's methodology, the median TSI value for Chlorophyll a must be 63 or less for two consecutive assessment/listing cycles before a lake can be removed from the state's Section 303(d) list (IR Category 5). Therefore, Snyder Bend Lake will remain listed as "not supported" for the 2020 assessment/listing cycle. 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 22970003 6 Ammonia 15 / 5 0.289 0.08 0.03 0 / 0 0% / 0% NO Monitored Full 22970003 6 Dissolved oxygen 15 / 5 14.3 9.81 9.2 NA / 0 NA / 0% NO Monitored Full 22970003 6 pH 15 / 5 8.9 8.4 8.4 0 / NA 0% / NA NO Monitored Full 22970003 6 Temperature 15 / 5 27.8 21.9 23.2 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 22970003 6 11 166.414 96.1 % 6.689 41 % NO Evaluated NA Class BLW - Fish Kill: The Class BLW uses that were assessed (evaluated) as "partially supporting" due to two fish kills in 2004 and 2005 have 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 359 7/17/17 largemouth bass plug 3
0.067 No Monitored Full
Additional Notes: Lake bathymetry was changed in 2011 when the lake was inundated by floodwaters. The lake was additionally became infested with Asian carp during this event.