Maquoketa River IA 01-MAQ-16

The Class A1 (primary contact recreation) uses remain assessed (monitored) as "not supported" due to violations of Iowa’s water quality criteria for indicator bacteria. The geometric means of E. coli in the 14 samples collected in 2012 and 2013 at Station 15280023 were 91 and 314 orgs/100 ml. Six of the 14 samples (43%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. Sampling in 2012 and 2013 at Station 15280004 showed that recreation season geometric means of E. coli in the 12 samples collected were 141 and 263 orgs/100. Six of the 12 samples (50%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. Similarly, sampling in 2012 and 2013 at station 16280001 showed a 2012 recreation season geometric mean of 495 orgs/100 ml and a 2013 recreation season geometric mean of 444 orgs/100 ml. Eleven of the 14 samples (79%) exceeded the single-sample maximum criterion. Recreation season geometric means at all three monitoring sites exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and DNR’s assessment/listing methodology, if the geometric mean of E. coli is greater than the state criterion of 126 orgs/100 ml., the primary contact recreation uses should be assessed as impaired (see pgs 3-33 to 3-35 of U.S. EPA 1997b).

Results of water quality monitoring in this assessment segment during the 2012-2014 period do not suggest impairment of the Class B(WW1) aquatic life uses. No violations of Class B(WW1) water quality criteria occurred in monitoring during 2012 and 2013 at stations 15280004 (above Lake Delhi), 15280023 (at 195th Street), and 16280001 for the following parameters: ammonia (combined 10 samples), dissolved oxygen (combined 22 samples), pH (combined 22 samples), and temperature (combined 22 samples).

The assessment of support of the Class B(WW1) uses was based on biological data collected in 2002, 2012 and 2013 as part of the DNR/SHL REMAP and follow-up sampling projects and on biological data collected in 2012-2016 by the DNR Manchester Fisheries sampling program. A series of biological metrics which 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 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 REMAP BMIBI score was 57 (good). The 2012 FIBI score was 62 (good) and the BMIBI score was 57 (good). The 2013 FIBI score was 82 (excellent) and the BMIBI score was 48 (fair). The 2012-2016 Fisheries FIBI scores (n=12) ranged from 19 (poor) to 73 (excellent). 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 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 non-riffle habitat FIBI BIC for this ecoregion is 44, the artificial substrate BMIBI BIC for this ecoregion is 52 and the natural substrate BMIBI BIC for this ecoregion is 70. One of the BMIBI scores of 57 was compared to the natural substrate BIC of 70 and the other two BMIBI scores were compared to the artificial substrate BMIBI BIC of 52. This segment passed the FIBI BIC 11/14 times in the last five years. This segment passed the BMIBI BIC 1/3 times in the last 15 years.

This aquatic life assessment is now considered "evaluated" based on a change in the 2010 DNR assessment methodology. DNR now requires a segment have two or more biological samples collected from the segment in multiple years over a five-year period to be considered “monitored”. This segment had multiple samples collected in the previous five years (2012-2016); however, the BMIBI results were inconclusive to finalize the assessment so 2002 data were also used. 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). Because, however, this impairment was previously included on Iowa’s Section 303(d) list, the impairment remains in Category 5b-t of Iowa’s 2014 Integrated Report.

Fish consumption uses remain assessed (monitored) as “fully supported” based on results of Iowa DNR fish contaminant monitoring downstream from the former Lake Delhi dam in 2011 and 2012. The sample of channel catfish fillets from the 2011 RAFT sampling downstream from the former Lake Delhi dam contained low levels of the primary contaminants (mercury: 0.169 ppm; total PCBs: <0.09 ppm; and technical chlordane: <0.03 ppm). The average level of mercury in the sample of smallmouth bass from this site, however, was 0.320 ppm (SD = 0.049) and was thus above the Iowa DNR advisory trigger level for mercury of 0.3 ppm. Follow-up monitoring was conducted on smallmouth bass as part of the 2012 RAFT, and levels of mercury were lower and below the mercury advisory trigger with an average level of mercury of 0.183 ppm (SD = 0.090). Based on the results of this follow-up monitoring, and based on results of the previous fish contaminant monitoring conducted in this river segment, the fish consumption uses are assessed (monitored) as “fully supporting”.