Monona-Harrison Ditch IA 06-LSR-1580
mouth (S21 T81N R45W Harrison Co.) to confluence of Wolf Cr. (aka Haitz Ditch) and West Fork Ditch in S12 T84N R45W Monona Co.
- Cycle
- 2018
- Release Status
- Final
- Overall IR
- 3 - Insufficient data exist to determine whether any designated uses are met.
- Trend
- Unknown
- Created
- 5/31/2019 7:40:33 AM
- Updated
- 7/30/2019 10:34:09 AM
The Class B(WW1) aquatic life uses remain assessed (evaluated) as “partially supported” based on results of biological sampling in 2006. The Class A1 (primary contact recreation) and Class HH (human health/fish consumption) uses remain "not assessed" due to the lack of data upon which to base an assessment.
The Class B(WW1) aquatic life uses remain assessed (evaluated) as "partially supporting" based on data collected in 2006 as part of the DNR/SHL stream REMAP project. A series of biological metrics that reflect stream water quality and habitat integrity were calculated from the biocriteria sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species 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 2006 FIBI score was 14 (poor) and the BMIBI score was 52 (fair). The aquatic life use support was assessed (evaluated) 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 31 and the BMIBI BIC for this ecoregion is 54. This assessment is considered evaluated because the drainage area (912 mi2) above this sampling site was greater than the maximum limit (500 mi2) that was used to calibrate the Iowa wadeable stream impairment criteria. Even though this site passed the BMIBI BIC (using the UAV of 8 points) and failed to meet the FIBI BIC, it is uncertain as to whether or not this segment is meeting the aquatic life criteria because the site used for the assessment doesn’t fall in the calibrated watershed size. According to DNR’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). DNR 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).