Boyer River IA 06-BOY-1500
mouth (Pottawattamie Co.) to confluence with Willow R. in S28 T78N R44W Harrison Co.
- Assessment Cycle
- 2018
- Release Status
- Final
- Data Collection Period
- Overall IR Category
- 3 - Insufficient data exist to determine whether any designated uses are met.
- Trend
- Unknown
- Created
- 5/30/2019 1:34:38 PM
- Updated
- 7/30/2019 12:39:55 PM
Assessment Summary
The Class A1 (primary contact recreation) and Class HH (fish consumption) uses remain "not assessed" due to the lack of information upon which to base an assessment. The Class B(WW1) aquatic life uses remain assessed (evaluated) as “partially supporting" based on data collected in 2003 as part of the DNR/SHL stream REMAP project.
Assessment Explanation
The Class B(WW1) aquatic life uses remain assessed (evaluated) as “partially supporting based on data collected in 2003 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 2003 FIBI score was 8 (poor) and the BMIBI score was 37 (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 (1,092 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 segmentfailed both the FIBI and BMIBI BICs, 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). 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).
Assessment Key Dates
8/13/2003 | Biological Monitoring |
Methods
150 | Monitoring data more than 5 years old |
315 | Regional reference site approach |
320 | Benthic macroinvertebrate surveys |
330 | Fish surveys |
380 | Quantitative physical habitat assessment |