Boyer River IA 06-BOY-1509
from confluence with East Boyer R. (S10 T83N R39W Crawford Co.) to confluence with Lime Cr. near Wall Lake in SE 1/4 S22 T86N R37W Sac Co.
The presumptive Class A1 (primary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of information upon which to base an assessment. The Class B(WW1) aquatic life uses remain assessed (evaluated) as “fully supporting” (IR 2a) based on results of biological sampling in 2002 conducted as part of the IDNR/SHL REMAP project. The Class HH (human health/fish consumption) uses remain “not assessed” (IR 3a) due to the lack of fish contaminant monitoring in this river segment.
[Note Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(WW) aquatic life uses, including fish consumption uses. Due to changes in Iowa’s surface water classification that were approved by U.S. EPA in February 2008 (see http://www.iowadnr.gov/Portals/idnr/uploads/water/standards/files/swcdoc2.pdf), this segment is also now presumptively designated for Class A1 (primary contact recreation) uses. This segment remains designated for warmwater aquatic life use (now termed Class B(WW1) uses), and for fish consumption uses (now termed Class HH (human health/fish consumption uses).] The Class B(WW1) aquatic life uses remain assessed (evaluated) as “fully supporting” based on results of biological monitoring conducted in 2002 as part of the IDNR/SHL REMAP project. A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biological sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species that were collected in the stream sampling reach. The biological metrics were combined to make a fish community index of biotic integrity (FIBI) and a benthic macroinvertebrate index (BMIBI). The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2002 FIBI score was 35 (fair) and the BMIBI score was 67 (good). The aquatic life use support was assessed (evaluated) as fully supporting (=FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports. The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008. The FIBI BIC for this ecoregion is 31 and the BMIBI BIC for this ecoregion is 54. This segment passed both the FIBI and BMIBI BICs in 2002. This aquatic life assessment is considered "evaluated" because there were not two or more samples collected from this segment in multiple years from over a recent five-year period. Additionally, because these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is considered “evaluated” (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence). Despite this change in assessment type, this waterbody remains in IR Category 2a. The fish consumption uses remain “not assessed” due to the lack of fish contaminant monitoring in this river segment.