Price Creek IA 02-IOW-6377

The presumptive Class A1 uses are assessed (monitored) as "partially supported" based on results of Section 319 bacteria monitoring from May 2013 to September 2014. From two to four samples from each of the seven monitoring stations on Price Creek were analyzed for E. coli during the recreation season of 2013; 11 samples were analyzed at each of the seven station during the 2014 recreation season. Note: According to the data completeness guidelines in Iowa DNR’s assessment/listing methodology, at least seven independent samples per recreation season are needed to calculate a geometric mean appropriate for comparison to the Class A geometric mean criteria. Too few samples (from 2 to 4) were collected at the seven monitoring stations during the 2013 recreation season to allow calculation of a useful geometric mean. During the 2014 recreation season, however, a sufficient number of samples was collected at each of the seven monitoring sites. The geometric mean levels of indicator bacteria (E. coli) at these seven stations and the number of samples exceeding the Class A1 single-sample maximum criterion of 235 orgs/100 ml were as follows (listed from downstream to upstream):

All seven stations exceed the Class A1 geometric mean criterion of 126 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and according to DNR’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 "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). Thus, the presumptive Class A1 uses are assessed as “partially supported”.

Biological sampling conducted in 2016 indicates that thepresumptive Class B(WW1) aquatic life usesshould be assessed (evaluated) as “fully supported”. This evaluated biological assessment was based on data collected in 2016 as part of the DNR headwater stream sampling project. A series of biological metrics that reflect stream water quality and habitat integrity were calculated from the fish sampling data. The biological metrics are based on the numbers and types fish species collected in the stream sampling reach. The biological metrics were combined to make a fish community index of biotic integrity (FIBI). The index ranks the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2016 FIBI score was 29 (fair). The aquatic life use support was assessed (evaluated) as fully supporting (=FS), based on a comparison of the FIBI score with biological impairment criteria (BIC) established from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008. The FIBI BIC for this ecoregion is 36 and this site passed the FIBI BIC 1/1 times in 2016.Even though this site passed the FIBI BIC (with the use of the FIBI UAV +7), it is uncertain as to whether or not this segment is meeting the aquatic life criteria because it is a small headwater stream and doesn’t fall in the calibrated watershed size.