Paint Creek (aka Pine Cr.) IA 01-UIA-257

Assessment Comments

Assessment is based on results of monitoring for indicator bacteria conducted at Site 22 of the Upper Iowa River Watershed (UIRW) project from April 2004 through October 2006 and on on an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in May 2006.

Basis for Assessment

[Note:  Prior to the current (2008) Section 305(b) cycle, this stream segment was designated only for Class B(CW) aquatic life uses.   Due to changes in Iowa’s surface water classification that were approved by U.S.  EPA in February 2008 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf), this segment is also now presumptively designated for Class A1 (primary contact recreation) and Class A2 (secondary contact recreation) uses.   This segment remains designated for coldwater aquatic life use (now termed Class B(CW1) uses), and for fish consumption uses (now termed Class HH (human health/fish consumption uses).   This stream segment also remains identified as an “HQR” (high quality resource) water.]

SUMMARY:  The pesumptive Class A1 (primary contact recreation) uses and the presumptive Class A2 (secondary contact recreation) uses are assessed (monitored) as “fully supported.”  The Class B(CW1) coldwater aquatic life uses  are assessed as "fully supported."  The fish consumption uses remain “not assessed” due to the lack of information upon which to base an assessment.   The source of data for this assessment is the results of monitoring for indicator bacteria conducted at Site 22 of the Upper Iowa River Watershed (UIRW) project from April 2004 through October 2006 and on on an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in May 2006.

EXPLANATION:  The presumptive Class A1 (primary contact recreation) uses and the presumptive Class A2 (secondary contact recreation) uses are both assessed (monitored) as “fully supported.”  Due to recent changes in Iowa’s Water Quality Standards, Iowa’s assessment methodology for indicator bacteria has changed.   Prior to 2003, the Iowa WQ Standards contained a high-flow exemption for the Class A1 criterion for indicator bacteria (fecal coliforms) designed to protect primary contact recreation uses:  the water quality criterion for fecal coliform bacteria (200 orgs/100 ml) did not apply "when the waters [were] materially affected by surface runoff."  Due to a change in the Standards in July 2003, E.  coli is now the indicator bacterium, and the high flow exemption was eliminated and replaced with language stating that the Class A criteria for E.  coli apply when Class A1, A2, or A3 uses “can reasonably be expected to occur.”  Because the IDNR Technical Advisory Committee on WQ Standards could not agree on what flow conditions would define periods when uses would not be reasonably expected to occur, all monitoring data generated for E.  coli during the assessment period, regardless of flow conditions during sample collection, will be considered for determining support of Class A uses for purposes of Section 305(b) assessments and Section 303(d) listings.  

The geometric mean of E.  coli in the 21 samples collected at UIRW Site 22 during the recreational seasons of 2004 through 2006 was 96 orgs/100 ml.   This geometric mean is below the Class A1 criterion of 126 orgs/100 ml and is far below the Class A2 criterion of 630 orgs/100 ml.   Three of the 21 samples (14%) exceeded Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml.; 1 of the 21 samples (5%) exceeded Iowa’s Class A2 single-sample maximum criterion (2,880 orgs/100 ml.).   According to U.S.  EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if the geometric mean of E.  coli is below the applicable state criterion, the primary contact recreation uses should be assessed as "fully supported" (see pgs 3-33 to 3-35of U.S.  EPA 1997b).   Also, according to U.S.  EPA guidelines for Section 305(b) reporting, if less than 10% of samples exceed the single-sample maximum criterion, the primary contact recreation uses should be assessed as "fully supported" (see pgs 3-33 to 3-35of U.S.  EPA 1997b).   According to IDNR’s assessment/listing methodology, the results from UIRW Site 23 do not indicate that significantly greater than 10% of the samples exceed either the Class A1 or Class A2 single-sample maximum criterions.   Thus, these results suggest that both the Class A1 and Class A2 uses should be assessed as “fully supported.”  

Based on an updated summary of trout reproduction in Iowa streams prepared by the DNR Fisheries Bureau in May 2006, the Class B(CW1) uses are assessed as "fully supported".   According to the updated summary, Paint Creek (aka Pine Cr.) is in the group of Iowa coldwater streams that supports natural reproduction of trout.   Based on results of surveys by the IDNR Fisheries Bureau, this stream is 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 for the resident trout species at this time.

Fish consumption uses remain “not assessed” due to the lack of information upon which to base an assessment.