Assessment Comments
Assessment based on results of (1) IDNR/UHL monitoring conducted in support of TMDL development in 2001, (2) IDNR/UHL biocriteria sampling in 2001 and (3) occurrence of two fish fills in July 2004.
Basis for Assessment
SUMMARY: The Class B(LR) aquatic life uses remain assessed (monitored) as “not supporting” due to (1) results of DNR/UHL biological monitoring in 2001 that show regionally poor biological integrity and (2) occurrence of two fish kills in July 2004.
EXPLANATION: The aquatic life use assessment was based, in part, on data collected in 2001 as part of the DNR/UHL stream biocriteria and TMDL development projects.
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 2001 FIBI scores were 29, 33, 26 (fair), and the BMIBI scores were 47, 51, 48 (fair). The FIBI average was 29.3 and the BMIBI average was 49. 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.
In addition to results of IDNR/UHL biological monitoring that suggest impairment of the Class B(LR) uses, two fish kills occurred in July 2004 that also suggest impairment of these uses. The first kill occurred on or before July 6, 2004; no cause of the kill was identified (cause “unknown”). An estimated 200 non-game fish (“minnows” and “suckers”) were killed over approximately 1.5 miles of stream. No estimate of the value of the fish killed was provided. The kill occurred in New Wine Park and upstream in Section 6 of T89N, R2W, Dubuque County. According to the IDNR investigation, he fish has been dead for a few days when they were discovered. The party responsible for the kill was not identified. This segment of the North Fork Maquoketa River has been affected by a number of fish kills over the 1995-2005 period.
An second kill that affected this assessment segment occurred on or before July 15, 2004. The kill was caused by a release of manure from an open feedlot dairy operation to an unnamed tributary to the North Fork Maquoketa River. An estimated 200 fish (“minnows”) were killed. Approximately 1 mile of stream was affected. This kill primarily affected the unnamed tributary (location information was not provided for this tributary). The IDNR investigation, however, suggested that the kill could affect the North Fork Maquoketa River [segment IA 01-NMQ-0020-2] as well. According to the IDNR investigation, a plywood stop in a manure control structure failed, releasing an estimated several thousand gallons of manure into the unnamed tributary. The owner of the farm worked quickly to address the spill, constructing an earthen dam, keeping most of the manure contained in the stream and out of the North Fork of the Maquoketa River. The collected manure was applied to cornfields. The manure caused a complete fish kill in the tributary, killing a few hundred creek chubs, stonerollers and minnows. The party responsible for the kill was not identified; IDNR records indicate no attempt to seek restitution for the value of the fish killed.
According to IDNR’s assessment and 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 is identified, and the cause is either known, or suspected, to be a “pollutant”, the assessment type is considered “monitored” and the affected waterbody is a candidate for Section 303(d) listing. Fish kills attributed to a pollutant, but where a source of the pollutant was not identified and/or where enforcement actions were not taken against the responsible party, will be placed into Integrated Report subcategory 5b. The intent of placing these waterbodies into Category 5 is not to necessarily require a TMDL but to keep the impairment highlighted due to the potential for similar future kills from the unaddressed causes and/or sources.
