Griswold Park Pond (aka Cocklin Fish Farm) IA 05-NSH-1417
Cass County S32T75NR37W at N edge of Griswold.
- Cycle
- 2018
- Release Status
- Final
- Overall IR
- 3 - Insufficient data exist to determine whether any designated uses are met.
- Trophic
- Unknown
- Trend
- Unknown
- Created
- 6/11/2019 12:52:53 PM
- Updated
- 8/2/2019 2:01:00 PM
The Class B(LW) (aquatic life) uses of Griswold Park Pond remain assessed (evaluated) as "partially supported" (IR Category 3b) due to a fish kill in June 2006. The fish consumption uses remain "not assessed" due to a lack of fish contaminant monitoring at this lake.
The Class B(LW) (aquatic life) uses remain assessed (evaluated) as "partially supported" due to a fish kill in June 2006. The kill occurred on or before June 21, 2006 and was attributed to natural causes (low dissolved oxygen due to an algal die-off). Approximately 1,260 fish were killed including: 1,249 bluegill, 6 largemouth bass, 3 grass carp, 2 channel catfish, and numerous young-of year bluegill and largemouth bass. Low oxygen conditions were likely caused by the treatment of the lake with copper sulfate to control algae on June 21, 2006. This along with high water temperatures (approaching 90 F) likely caused low oxygen levels. It is likely that low oxygen conditions existed during the evening of June 22 to the morning of June 23. Dead and struggling fish were observed on the morning of June 23. By the afternoon of June 23, oxygen readings ranged from 4-10 ppm throughout the pond and no additional dead fish were observed during subsequent visits. It was noted that young-of-the-year fish may also have died from toxic levels of copper following the application. The value of dead fish was estimated to be $ 19,112.40.
This is the same assessment as that developed for the previous assessment/listing cycles. The continuance of the IR Category 3b listing is based on DNR's assessment methodology that states the following:the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired”. If a cause of the kill was not identified during the DNR investigation, or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated” and will be placed in IR subcategories 2b or 3b and will be added to the state list of waters in need of further investigation. Thus, this assessment segment will remain in Category 3b of Iowa’s Integrated Report.