Assessment Comments
Assessment is based on (1) results of USGS ambient monitoring in 2002, (2) IDNR / UHL biological (REMAP) monitoring in 2002, (3) U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2002, and (4) an IDNR investigation of a fish kill in Lake Delhi in August 2004.
Basis for Assessment
SUMMARY: The Class A (primary contact recreation) uses are assessed (evaluated) as “not supported” due to levels of indicator bacteria that exceeds state water quality criteria. The Class B(WW) are assessed (monitored) as “partially supported” based on results of DNR/UHL biological (REMAP) monitoring in 2002 and 2002 IDNR Fisheries sampling. This assessment is independent of Lake Delhi in which a fish kill occurred in August 2004. Fish consumption uses are assessed as “fully supported” based on results of fish contaminant monitoring in 2002. Sources of data used for this assessment include (1) results of USGS monitoring on the Maquoketa River at Manchester from March to July, 2002, (2) IDNR/UHL biological (REMAP) monitoring in 2002, (3) results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2002, and (4) results of an IDNR investigation of a fish kill in Lake Delhi in August 2004.
EXPLANATION: The Class A (primary contact recreation) uses were assessed (evaluated) as "partially supported" due to violations of Iowa’s water quality criteria for indicator bacteria. Due to recent changes in Iowa’s Water Quality Standards, Iowa’s 2006 assessment methodology for indicator bacteria has changed. Prior to 2003, the Iowa WQ Standards contained a high-flow exemption for the Class A criterion for indicator bacteria (fecal coliforms) designed to protect primary contact recreation uses: the water quality criterion for fecal coliform bacteria (200 orgs/100 ml) did not apply "when the waters [were] materially affected by surface runoff." Due to a change in the Standards in July 2003, E. coli is now the indicator bacterium, and the high flow exemption was eliminated and replaced with language stating that the Class A criteria for E. coli apply when Class A1, A2, or A3 uses “can reasonably be expected to occur.” Because the IDNR Technical Advisory Committee on WQ Standards could not agree on what flow conditions would define periods when uses would not be reasonably expected to occur, all monitoring data generated for E. coli during the assessment period, regardless of flow conditions during sample collection, will be considered for determining support of Class A uses for purposes of the 2006 Section 305(b) assessments and Section 303(d) listings.
The geometric mean of E. coli in the 3 samples collected was 244 orgs/100 ml (maximum sample value = 1,100 orgs/100 ml; minimum sample value = 100 orgs/100 ml). One of the 3 samples (33%) exceeded Iowa’s single-sample maximum value of 235 orgs/100 ml. 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 "not supported" (see pgs 3-33 to 3-35of U.S. EPA 1997b). Although the geometric mean (244 orgs/100 ml) is well above the state water quality criterion of 126 orgs/100 ml too few data points are available do develop a “high confidence” assessment. According to the IDNR assessment methodology a minimum of ten samples is required for a “monitored” (higher confidence) assessment based on levels of indicator bacteria; assessments developed with fewer than 10 samples are considered “evaluated” (lower confidence) and are not typically appropriate for Section 303(d) listing. Because far fewer than 10 samples were available for this assessment, IDNR considers the assessment of support of the Class A uses as of relatively low confidence (evaluated) and thus not appropriate for Section 303(d) listing.
Despite the occurrence of a fish kill in Lake Delhi in August 2004, the Class B(WW) aquatic life uses of the flowing portion of this segment of the Maquoketa River were assessed (evaluated) as "fully supported" based on results of limited water quality monitoring by the U.S. Geological Survey at Manchester in 2002. No violations of state Class B(WW) water quality criteria occurred in the three samples analyzed for dissolved oxygen, pH, ammonia, and toxic metals from March to July 2002. Although these results indicate “full support” of the aquatic life uses of this river segment, the number of samples is low and is far below IDNR guidelines for developing a “monitored” (i.e., higher confidence) assessment. Thus, the assessment type is considered “evaluated” (lower confidence).
The assessment of support of the Class B(WW) uses was also based on data collected in 2002 as part of the DNR/UHL REMAP project (Regional Environmental Monitoring and Assessment Program) and on data collected in 2002 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 2002 Fisheries FIBI scores were 48 (fair), 60 (good) and 71 (excellent). 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 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 1994-2004. The non-riffle site FIBI BIC for this ecoregion is 44 and the natural substrate BMIBI BIC for this ecoregion is 70.
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 were assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring at Bailey’s Ford Access southeast of Manchester in Delaware County. The composite samples of fillets from channel catfish and largemouth bass had low levels of contaminants. Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.56 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.
The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of the degree to which Iowa’s lakes and rivers support their fish consumption uses. Prior to 2006, IDNR used action levels published by the U.S Food and Drug Administration to determine whether consumption advisories should be issued for fish caught as part of recreational fishing in Iowa. In an effort to make Iowa’s consumption more compatible with the various protocols used by adjacent states, the Iowa Department of Public Health, in cooperation with Iowa DNR, developed a risk-based advisory protocol. This protocol went into effect in January 2006 (see http://www.iowadnr.gov/fish/news/consump.html for more information on Iowa’s revised fish consumption advisory protocol). Because the revised (2006) protocol is more restrictive than the previous protocol based on FDA action levels; fish contaminant data that previously suggested “full support” may now suggest either a threat to, or impairment of, fish consumption uses. This scenario, however, does not apply to the fish contaminant data generated from the 2002 RAFT sampling conducted in this assessment segment: the levels of contaminants do not exceed any of the new (2006) advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody.
