Assessment Comments
Assessment based on results of IDNR monitoring in May and June, 2012 at two stations: (1) Maquoketa River at Honey Creek Bridge (Station 15280023), (2) near Schram Park in Manchester (Station 16280001), (3) results of fish tissue monitoring downstream from the former Lake Delhi dam in 2011 and 2012. Assessment is also based on historic data upon which the existing impairments of the Class A1 and Class B(WW1) uses are based.
Basis for Assessment
SUMMARY: The Class A1 (primary contact recreation) uses remain assessed (monitored) as “partially supported” (IR 5a) due to levels of indicator bacteria that exceeds state water quality criteria. The Class B(WW1) uses are assessed (evaluated) as “partially supported” (IR 5b-t) based on results of IDNR/SHL biological sampling in 2002, 2012 and 2013 and on results of IDNR Fisheries biological monitoring in 2002, 2004 and 2006. This assessment is independent of the assessment for Lake Delhi in which a fish kill occurred in August 2004. Fish consumption uses remain assessed as “fully supported” (IR 2a) based on results of fish contaminant monitoring in 2011 and 2012. Sources of data used for this assessment include (1) results of IDNR monitoring in May and June, 2012, at two stations: Maquoketa River at Honey Creek Bridge (Station 15280023) and near Schram Park in Manchester (Station 16280001), (2) IDNR/SHL biological sampling in 2002, 2012 and 2013, (3) IDNR Fisheries bureau fish sampling in 2002, 2004, and 2006, and (4) results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2011 and 2012 downstream from the former Lake Delhi dam. In addition, the assessment is based on the results of the following historic water quality monitoring:
(1) at Manchester (upstream from dam; near Tirrill Park; STORET station 11280001) from April to September 2005, (2) results of monitoring in 2006 by the Lake Delhi Watershed Association on the Maquoketa River (STORET station 15280004), (3) results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2002, (5) results of fish contaminant monitoring conducted as part of the IDNR/SHL REMAP biological monitoring project in 2006, (6) results of an IDNR investigation of a fish kill in Lake Delhi in August 2004.
EXPLANATION: The Class A1 (primary contact recreation) uses are assessed (monitored) as "partially supported" due to violations of Iowa’s water quality criteria for indicator bacteria. The geometric mean of E. coli in the 12 samples collected in 2005 at the IDNR/UHL TMDL station at Manchester was 461 orgs/100 ml. Ten of the 12 samples (83%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. More recently, bacteria monitoring in this segment from May-June 2012 showed that the geometric mean of the seven samples collected near Schram Park in Manchester was 495 orgs/100 ml with five of the seven samples (71%) exceeding Iowa’s single-sample maximum criterion of 235 orgs/100 ml. Monitoring during the same (May-June) period in 2012 upstream from Manchester below the Quaker Mill dam, however, showed a geometric mean of only 91 orgs/100 ml with only one of the seven samples (14%) exceeding the single-sample maximum criterion. According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’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). Although the results of monitoring at stations near Schram Park in Manchester in 2012 do not meet IDNR data quantity requirements for a “monitored” assessment (at least 10 samples collected over a three-year period), these data combined with the historical data on bacteria levels suggest that the geometric mean levels of E. coli are above the Class A1 criterion. Thus the bacterial impairment of the Class A1 uses of this assessment segment should continue. Data generated as part of the Lake Delhi watershed assessment in 2006 also suggest impairment of the Class A1 uses. The geometric mean for E. coli in the seven samples collected in the Maquoketa River above Lake Delhi near Bailey’s Ford County Park (STORET station 15280004) from April to June, 2006 (1,146 orgs/100 ml) far exceeded the Iowa geometric mean criterion of 126 orgs/100 ml; levels of E. coli in five of the seven samples exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml.
Despite the occurrence of a fish kill in Lake Delhi in August 2004, results of water quality monitoring in 2005 suggest that the Class B(WW1) aquatic life uses in the flowing portion of this assessment segment should be assessed (monitored) as "fully supported". Results of water quality monitoring by the IDNR/SHL at the TMDL station at Manchester from April through September 2005 show no violations of state Class B(WW1) water quality criteria in the 12 samples analyzed for dissolved oxygen and pH or in the 11 samples analyzed for ammonia.
The assessment of support of the Class B(WW1) uses (partially supported, evaluated: IR 5b-t) was based on biological data collected in 2002, 2012 and 2013 as part of the IDNR/SHL REMAP and follow-up sampling projects and on biological data collected in 2002, 2004 and 2006 by the 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 FIBI score was 59 (good) and the BMIBI score was 57 (good). The 2012 FIBI score was 61 (good) and the BMIBI score was 57 (good). The 2013 FIBI score was 82 (excellent) and the BMIBI score was 48 (fair). The 2002 Fisheries FIBI scores were 48 (fair), 58, 59, 60 (good) and 71 (excellent). The 2004 Fisheries FIBI score was 55 (good). The 2006 Fisheries FIBI score was 48 (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 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 all 10 times in the last 12 years. This segment passed the BMIBI BIC 1/3 times in the last 12 years.
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 over a five-year period to be considered “monitored”. This segment had multiple samples collected in the previous five years (2012-2013); however, the results were inconclusive to finalize the assessment so 2002 data were also used. 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). 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.
A fish kill occurred in Lake Delhi in August 2004. This kill occurred on or before August 9, 2004. The kill was reported to occur between Freddy’s Beach and the Lake Delhi Dam. Based on the investigation conducted by the IDNR Fisheries Bureau, the kill was attributed to natural causes. A malfunctioning aeration system may have played a role in the kill. An estimated 330 fish were killed; no estimate of the value of the fish killed was provided. According to the IDNR investigation, fish killed included bluegills and channel catfish. According to IDNR’s assessment/listing methodology, the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period (2002-2005) indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired”. If a cause of the kill was not identified during the IDNR investigation, or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated.” Such assessments, although suitable for Section 305(b) reporting, lack the degree of confidence to support addition to the state Section 303(d) list of impaired waters (IR Category 5). Waterbodies affected by such fish kills will be placed in IR subcategories 2b or 3b and will be added to the state list of waters in need of further investigation.
Fish consumption uses are assessed (monitored) as “fully supported” based on results of fish contaminant monitoring at (1) the U.S.EPA/IDNR fish contaminant (RAFT) monitoring site at Bailey’s Ford Access southeast of Manchester in Delaware County in 2002, (2) the REMAP site 28 in 2006, and (3) U.S. EPA/IDNR RAFT monitoring downstream from the former Lake Delhi dam in 2011 and 2012. The composite samples of fillets from channel catfish and largemouth bass from the 2002 RAFT monitoring and the samples of common carp fillets from the 2006 REMAP monitoring all had low levels of contaminants. In the RAFT samples, levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.056 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. Levels of primary contaminants in the composite sample of largemouth bass fillets were as follows: mercury: 0.196 ppm; total PCBs: <0.09 ppm; and technical chlordane: <0.03 ppm. In the 2006 REMAP samples, levels of primary contaminants in the composite sample of common carp fillets were as follows: mercury: 0.178 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. Levels of all contaminants in these samples were below fish consumption advisory trigger levels as specified in Iowa’s fish consumption advisory protocol (see http://www.iowadnr.gov/Environment/WaterQuality/WaterMonitoring/MonitoringPrograms/FishTissueMonitoring.aspx).
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: 0.17 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 0.32 ppm 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 0.18 ppm. 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”.
