Sny Magill Creek IA 01-YEL-430
mouth (S23 T94N R3W Clayton Co.) to west line of S6 T94N R3W Clayton Co.
- Cycle
- 2018
- Release Status
- Final
- Overall IR
- 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
- Trend
- Unknown
- Created
- 8/1/2019 2:18:54 PM
- Updated
- 8/30/2019 8:56:37 AM
The presumptive Class A1 (primary contact recreation) uses and presumptive Class A2 (secondary contact recreation) uses remain "not assessed" due to the lack of data for indicator bacteria upon which to base an assessment. The Class B(CW1) coldwater aquatic life uses remain assessed (monitored) as "fully supported". Fish consumption (Class HH) uses remain "not assessed" due to the lack of fish contaminant monitoring in this coldwater stream. The primary sources of data for this assessment is the summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in January 2019. Supplemental, and outdated sources of water quality information include results of water quality monitoring conducted from January 2000 through September 2001 at three sites on Sny Magill Creek: Site 1 (IDNR station 15220004), Site 2 (DNR station 15220005), Site 3 (DNR station 15220002).
The Class B(CW1) uses remain assessed as "fully supported" based on an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in 2019. According to the updated summary, Sny Magill Creek is in the group of Iowa coldwater streams that supports natural reproduction of trout. In previous DNR summaries of trout reproduction, this stream was placed in the category of Iowa trout streams that have fairly consistent natural reproduction and that are capable of maintaining a viable population Brown Trout without any stocking (a Category I stream). Based on results of surveys by the DNR Fisheries Bureau, however, Sny Magillis now placed in the category of Iowa trout streams that exhibit recent, but inconsistent reproductive success and that are generally not capable of maintaining a viable population of Brown Trout at this time (a Category II stream). Although still considered “fully supporting”, this assessment based on the 2019 summary of trout reproduction reflects continuance of a decline in the ability of this stream to support natural reproduction of trout. Monitoring of chemical water quality, habitat quality, fish populations, and aquatic macroinvertebrate populations was conducted at Sny Magill Creek from 1992 to the early 2000's as part of the Sny Magill Creek Nonpoint Source Pollution Monitoring Project. Results of this monitoring showed good chemical water quality and aquatic life. Previous assessments of aquatic life uses in this stream segment as "fully supported" were based on results of chemical and biological water quality monitoring conducted from 1992 through 2001 at three monitoring sites (see previous assessments). Of the approximately 200 samples analyzed at these stations during 2000-01, no samples violated the respective Class B(CW) water quality criteria for dissolved oxygen and temperature. All these data, however, have aged well beyond the ten-year period during which water quality data is considered able to characterize current water quality conditions. Thus, the results of the monitoring from 1999-2001 may have little relevance to current water quality conditions in this assessment segment. Fish consumption uses remain "not assessed" due to lack of fish tissue monitoring in this stream reach.