Iowa County, Wisconsin
SP06
910800
16.52 - 20.30
3.78
Water is impaired due to one or more pollutants and associated quality impacts.
Notes
TMDL approved 2005.
Point sources are not contributing to impairment in this segment.For all of the following streams, sedimentation is causing habitat degradation. Sedimentation reduces the suitable
habitat for fish and macroinvertebrate communities. Filling-in of pools reduces the amount of available cover for
juvenile and adult fish. Sedimentation of riffle areas reduces the reproductive success of fish by reducing the exposed
gravel substrate necessary for appropriate spawning conditions. Sedimentation also affects macroinvertebrate biomass
(fish food source) which tends to be lower in areas with predominantly sand substrate than a stream substrate with a
mix of gravel, rubble, and sand. Sedimentation also causes elevated turbidity which reduces the penetration of light necessary for photosynthesis in aquatic plants, reduces the feeding efficiency of visual predators and filter feeders, and lowers the respiratory capacity of aquatic invertebrates by clogging their gill surfaces. In addition, other contaminants such as nutrients (phosphorus) attached to sediment particles can be transported to streams during runoff events. The following is a stream by stream description, based on information obtained from WDNR files.
This water was assessed during the 2016 listing cycle; total phosphorus sample data exceed 2016 WisCALM listing criteria for the Fish and Aquatic Life use and biological impairment was observed (i.e. at least one macroinvertebrate or fish Index of Biotic Integrity (IBI) scored in the poor condition category).
This water was assessed during the 2018 listing cycle; new total phosphorus sample data exceed 2018 WisCALM listing criteria for the Fish and Aquatic Life use and biological impairment was observed (i.e. at least one fish Index of Biotic Integrity (IBI) scored in the poor condition category).
Assessments during the 2020 listing cycle showed fish sample data in good condition. Pollutant
Total Phosphorus
Listed For
Fish and Aquatic Life
Impairments
Degraded Biological Community
Current Use
Unsupported Aquatic Life
Listing Status
303d Listed
Attainable Use
WWSF - Warmwater Sport Fishery
Priority
Medium
Designated Use
WWSF - Warmwater Sport Fishery
303(d) ID
2016-112
Listing Date
4/1/2016
Impaired Water Notes
This water was assessed during the 2016 listing cycle; total phosphorus sample data exceed 2016 WisCALM listing criteria for the Fish and Aquatic Life use and biological impairment was observed (i.e. at least one macroinvertebrate or fish Index of Biotic Integrity (IBI) scored in the poor condition category).
Date
8/24/2015
Pollutant
Sediment/Total Suspended Solids
Listed For
Fish and Aquatic Life
Impairments
Degraded Habitat
Current Use
Unsupported Aquatic Life
Listing Status
TMDL Approved
Attainable Use
WWSF - Warmwater Sport Fishery
Priority
Not Applicable
Designated Use
WWSF - Warmwater Sport Fishery
303(d) ID
12237-113
Listing Date
4/1/1998
Impaired Water Notes
Dodge Branch is a twenty-two mile long; spring fed tributary originating in central Iowa County, just north of Dodgeville. The stream is part of the Upper East Branch Pecatonica River watershed, and flows southeast, draining into the East Branch of the Pecatonica River near Hollandale. Dodge Branch is separated into three segments on the 303(d) list for modeling purposes. However, based on a review of designated uses, Dodge Branch contains four segments and all have degraded habitat due to sedimentation. The upper mile (miles 21-22) of the stream is codified as a limited forage fishery. This section receives wastewater discharge from Dodgeville, and is impacted by urban non-point source pollution.
Stream miles 17 through 21 are codified as a warm water sport fishery. Four fish surveys were conducted in this portion of the stream in 2001. Between the four surveys, 14 brown trout, three channel catfish, and 20 forage and minnow species were seen. The most abundant forage species were white sucker, central stoneroller, and creek chub. Habitat surveys in this portion of the stream found that approximately 70% of the substrate was composed of gravel or coarser material which suggests “good” habitat quality.
Stream miles 10 through 17 are codified as a cold-water fishery. Although this section of the stream receives cold water from some tributaries, urban non-point source pollution, streambank pasturing, and hydraulic manipulation negatively affect the water quality. One habitat evaluation was performed in 2001 in the section of stream codified as a cold water fishery. The survey found that about 75% of the stream bottom was composed of gravel or coarser material, and about 15% was composed of silt, indicating “good” habitat quality for this section of the stream. One fish survey was conducted in this section, also in 2001. Warm water forage species such as creek chub and white sucker were most common, and only one brown trout was found, indicating “poor” biotic integrity for a cold-water stream.
The lowest section of this stream, miles 0-10, is codified as a warm water sport fishery. Discharge from Hollandale’s municipal wastewater treatment facility, stream bank pasturing, and non-point source pollution all contribute to the turbid water seen in this section of the stream. In 2004, three sites on the lower portion of Dodge Branch, downstream of Jonesdale, underwent IBI surveys. Two brown trout and one small mouth bass were found, in addition to 12 forage and minnow species, with the most abundant being common shiner and white sucker.
Date
6/28/2005
Impaired Water Notes
Dodge Branch (910800, miles 0-20.3) is part of the Sugar-Pecatonica River Basin and the sediment TMDLs were approved by the USEPA August 24, 2005.
Date
4/25/2005