Assessment Comments
Assessment remains based on results of IOWATER monitoring from 2005-2008 and is based on Section 319 monitoring bacteria monitoring from June to November 2011..
Basis for Assessment
[Note: Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(LR) aquatic life 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. The stream remains designated for aquatic life uses (now termed Class B(WW2) aquatic life uses). Thus, for the current assessment, the available water quality monitoring data was compared to the applicable Class A1 and Class B(WW2) water quality criteria.]
SUMMARY: The presumptive Class A1 (primary contact recreation) uses are assessed (monitored) as “not supported” (IR 5p) due to levels of indicator bacteria (E. coli) that exceed state water quality criteria. The Class B(WW2) aquatic life uses remain assessed (monitored) as "fully supported” (IR 2a) based on results of chemical/physical monitoring conducted from 2005 through 2008. This sources of data for this assessment are the results of an IOWATER volunteer monitoring project from 2005-2008 and a Section 319 water quality monitoring project conducted from June to November 2011 on Price Creek at the following stations (moving from downstream to upstream): (1) Site 11A at 220th Trail at Amana (STORET IDs 948061 (IOWATER) and 13480013 (319)), (2) Site 10 at Highway 151 (STORET IDs 948075 (IOWATER) and 13480012 (319), (3) Site 9 above campground (STORET IDs 948063 (IOWATER) and 13480011 (319)), and (4) Site 8 at U Avenue (STORET IDs 948065 (IOWATER) and 13480010 (319)).
EXPLANATION: The presumptive Class A1 uses remain assessed (monitored) as "not supported" based on results of Section 319 monitoring from June to November 2011. Eleven samples were collected from each of the four monitoring stations on Price Creek and were analyzed for E. coli during the recreation seasons of 2011. The geometric mean level of indicator bacteria (E. coli) at all four stations far exceed the Class A1 geometric mean criterion of 126 orgs/100 ml: Site 11: 1,473 orgs/100 ml; Site 10: 1,798 orgs/100 ml, Site 9: 1,954 orgs/100 ml; and Site 8: 469 orgs/100 ml. From 82 to 100% of the samples at each of the four station exceeded the Class A1 single-sample maximum criterion of 235 orgs/100ml. According to U.S. EPA guidelines for Section 305(b) reporting and according to IDNR’s assessment/listing methodology, if the geometric mean level of E. coli is greater than the state criterion, the primary contact recreation uses should be assessed as "not supported" (see pgs 3-33 to 3-35of U.S. EPA 1997b).
The Class B(WW2) aquatic life uses remain assessed (monitored) as “fully supporting” based on results of the water quality monitoring in this segment of Price Creek from 2005-2008. (The only supporting parameter with Class B(WW1) criteria that was collected as part of Section 319 monitoring in 2011 was water temperature; none of the combined 32 samples collected at the four stations violated the Class B(WW2) criterion for water temperature.) Results for dissolved oxygen, pH, and ammonia show no violations of Class B(WW2) criteria in the approximately 10 samples collected at each of the four monitoring stations in this segment (i.e., PC-11, PC-10, PC-9, and PC-8). The lack of violations suggests “full support” Class B(WW2) aquatic life uses. Note: because the pH data were recorded to the nearest whole pH unit, these data were not useful for determining the strongly pH-dependent violations of aquatic life criteria for ammonia. As monitored from 2005-2008, however, levels of ammonia in this segment of Price Creek are very low: the maximum level reported in the 14 samples analyzed was 0.08 mg/l with 12 of 14 samples reported as less than the detection level of 0.05 mg/l.
