Little Waterman Creek IA 06-LSR-1621
mouth (S4 T95N R39W O'Brien Co.) to headwaters in S15 T96N R40W O'Brien Co.
- Cycle
- 2016
- Release Status
- Final
- Overall IR
- 3 - Insufficient data exist to determine whether any designated uses are met.
- Trend
- Unknown
- Created
- 9/7/2016 2:41:38 PM
- Updated
- 10/11/2016 11:56:33 AM
The presumptive Class A1 (primary contact recreation) uses remain "not assessed" (IR Category 3a) due to the lack of information upon which to base an assessment. The presumptive Class B(WW1) aquatic life uses are assessed (evaluated) as "partially supported" (IR Category 3b-u) based on results of IDNR/SHL biological sampling in 2002, 2008 and 2013.
The assessment of the presumptive Class B(WW1) aquatic life uses was based on data collected in 2002, 2008 and 2013 as part of the IDNR/SHL stream biocriteria project. The 2002, 2008 and 2013 FIBI scores were 42 (fair), 62 (good) and 56 (good) and the BMIBI scores were 46, 54 and 51 (all fair). The aquatic life use support was assessed as partially supporting (=PS), based on a comparison of the FIBI and BMIBI scores 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 43 and the BMIBI BIC for this ecoregion is 54. This segment passed the FIBI BIC 2/3 times and passed the BMIBI BIC 1/3 times in the last 13 years. Even though this site passed the FIBI BIC and failed the BMIBI BIC, 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. Prior to the changes in Iowa’s surface water classification that were approved by U.S. EPA in February 2008, this stream was classified only for general uses due to the inability of the stream to support a viable aquatic community at low-flow conditions. IDNR’s existing biological assessment protocol, however, was calibrated to aquatic life reference conditions in larger wadeable streams with perennial flow. The aquatic environment of most headwater streams is one of extremes in water quality. Consequently, intermittent headwater streams tend to have biological diversity that is low relative to more stable aquatic environments of larger streams with perennial flow. Thus, the use of biological assessment methods developed for the ecologically more stable and diverse streams will likely overstate the existence of impairment in headwater streams.