Assessment Comments
Assessment based on 2006 IDNR/UHL biological monitoring data: 1/8, 1/8 coldwater biological indicators met the criteria - not supporting (NS).
Basis for Assessment
Note: Prior to the 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.
SUMMARY: The Class A1 (primary contact recreation) and Class A2 (secondary contact recreation) uses remain “not assessed” due to the lack of sufficient water quality data or other information upon which to base an assessments. The Class B(CW1) coldwater aquatic life uses remain assessed (monitored) as “not supporting” due to a biological impairment. Fish consumption uses remain “not assessed” due to the lack of fish contaminant monitoring in this stream segment. The source of data used for this assessment is biological monitoring conducted on Pecks Creek in 2006 as part of the IDNR/UHL TMDL sampling project.
EXPLANATION: The presumptive Class A1 and A2 uses of this stream remain “not assessed” due to the lack of information upon which to base an assessment. Single samples of E. coli were collected at two monitoring sites on this stream in August 2006: (1) STORET station 11220012 near Osterdock (TMDL site No. 326) and (2) STORET station 11220013 near Osterdock (TMDL site No. PeC2). The level of E. coli in the sample from TMDL site 326 was 290 orgs/100 ml; the level in the sample from TMDL site PeC2 was 64 orgs/100 ml. This small amount of data (total of two samples from two stations) neither meets IDNR guidelines for developing Section 305(b) water quality assessments nor allows calculation of summary statistics (i.e., geometric mean) needed to develop an assessment of the degree to which the Class A uses are supported.
The assessment of the Class B(CW1) coldwater aquatic life uses remains based on data collected in 2006 as part of a TMDL sampling project. A series of eight (8) coldwater biological indicators, which reflect stream water quality and habitat integrity, were calculated from the REMAP sampling data and supplemental IDNR Fisheries Bureau data. The coldwater biological indicators are based on the numbers and types of coldwater benthic macroinvertebrate taxa and fish species that were collected in the stream sampling reach. Sites that score 5-8 are Fully Supporting (FS), sites that score 2-4 are Partially Supporting (PS), and sites that score 0-1 are Not Supporting (NS). The 2006 coldwater biological indicator scores were 1/8 and 1/8. The aquatic life use support was assessed as not supporting (=NS), based on a comparison of the coldwater biological indicator score with biological assessment criteria established for this Section 305(b) report. The coldwater biological indicators were determined from a statistical analysis of data collected at coldwater stream ecoregion reference sites from 1994-2008 and with assistance from the IDNR Fisheries Bureau. As part of the 2002 REMAP project, stream physical habitat assessment found adverse conditions that are thought to contribute to the biological impairment. These include, bank instability, flow impoundment, and excessive silt deposition. Beaver activity in the vicinity of the sample site has been observed and is suspected to be a major source of habitat alteration.
This aquatic life assessment is now considered "evaluated" based on a change in the 2010 IDNR assessment methodology. IDNR now requires a segment have two or more biological samples collected from the segment in multiple years between 2004 and 2008 to be considered “monitored”. This segment had multiple samples collected in 2006; however, the samples were not collected in multiple years. According to IDNR’s assessment/listing methodology, impairments based on “evaluated” assessments are of lesser confidence and are thus not appropriate for Section 303(d) listing (Category 5 of the Integrated Report). IDNR does, however, consider these impairments as appropriate for listing under either Category 2b or 3b of the Integrated Report (waters potentially impaired and in need of further investigation). However, despite this change in assessment methodology and type, this waterbody remains in IR Category 5b and remains on Iowa’s 2010 Section 303(d) list of impaired waters.
Similar to the case for assessing support of the Class A uses of this stream, insufficient water quality data are available from the two TMDL monitoring sites on this stream to develop an assessment for the support of the Class B(CW1) coldwater aquatic life uses. Single samples were collected at both stations in August 2006. The levels of ammonia and pH at both stations (TMDL site No. 326 and TMDL site No. PeC2) were below the Class B(CW1) chronic criteria. This small amount of data, however, neither meets IDNR guidelines for developing Section 305(b) water quality assessments nor allows calculation of summary statistics (e.g., percent violations based on at least 10 samples) needed to develop an assessment of the degree to which the aquatic life uses are supported.
Fish consumption uses remain “not assessed” due to lack of fish contaminant monitoring in this stream segment.
