Assessment Comments
Assessment remains based on results of a use attainability analysis (UAA) conducted by IDNR staff in September 2006.
Basis for Assessment
[Note: Prior to the 2008 Section 305(b) cycle, this stream segment was classified only for general uses. Due to changes in Iowa’s surface water classification that were approved by U.S. EPA in February 2008, this segment is now presumptively designated for Class A1 (primary contact recreation) uses and for Class B(WW1) aquatic life uses. According to the Iowa Water Quality Standards, all perennial rivers and streams and all intermittent streams with perennial pools that are not specifically listed in the Iowa surface water classification are designated as Class A1 and Class B(WW1) waters. Thus, for the current assessment, perennial flow is presumed, and the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW1) water quality criteria.]
SUMMARY: The general uses of this stream remain assessed (evaluated) as "not supported" (IR 5a) due to impacts of poorly-treated wastewater discharged to the stream that result in a violation of Iowa’s narrative water quality criteria (IAC 61.3(2)). Waters assessed as “not supported” are appropriate for addition to Iowa’s Section 303(d) list of impaired waters and this segment was placed in Category 5a of Iowa’s 2010 Integrated Report. This segment remains in Category 5a of Iowa’s Integrated Report. The presumptive Class A1 (primary contact recreation) and presumptive Class B(WW1) aquatic life uses remain “not assessed” (IR 3a) due to (1) the lack of sufficient biological data (i.e., data collected according to INDR biological assessment protocols) and (2) the lack of an appropriate assessment protocol to identify impairments of aquatic life uses of headwater streams.
EXPLANATION: The identification of the impairment of the general uses for this assessment segment is based on results of observations and biological monitoring conducted by IDNR staff on September 26, 2006 as part of a use attainability analysis for Prairie Creek in Johnson County near the outfall of the Lone Tree WWTP. The following comments from the UAA are relevant to this assessment (see http://programs.iowadnr.gov/uaa/search.aspx):
“The effluent coming from the Lone Tree WWTP discharge pipe smelled strongly of sewage. The creek and the creek bed at site (539-3) near the outfall smelled of sewage. There was a white fungus found in the creek at this site. The water in the creek was a milky color in places. It should be noted that upstream of the WWTP discharge pipe, there was no smell and the water in the creek was clear. At the downstream sites, the creek appeared normal. No white fungus was observed and the creek did not smell of sewage.” (http://programs.iowadnr.gov/uaa/resources1/uaa/136/Prairie%20Creek%20-%20Recreation%20UA-UAA.doc )
These comments suggest poor water quality conditions and potential violations of several of Iowa's narrative water quality standards (IAC 61.3(2)) designed to protect general uses of Iowa's surface waters (e.g., livestock and wildlife watering, aquatic life and non-contact recreation):
--such waters shall be free from substances from point source dischargers that will settle to form sludge deposits;
--such waters shall be free from floating debris, oil, grease, scum and other materials from wastewater discharges or agricultural practices in amounts sufficient to create a nuisance;
--such waters shall be free from materials from wastewater discharges or agricultural practices producing objectionable color, odor, or other aesthetically objectionable conditions;
--such waters shall be free from substance attributable to wastewater discharges or agricultural practices in concentrations or combinations which are acutely toxic to human, animal, or plant life.
Based on the information from the September 2006 UAA, the general uses of this stream segment are assessed (monitored) as "not supported" due to water quality impacts from poorly-treated domestic sewage. Waters assessed as “monitored/not supported” are considered appropriate for addition to Iowa’s Section 303(d) list of impaired waters.
