Mill Creek, Mill and Blue Mounds Creek Watershed (LW15)
Mill Creek, Mill and Blue Mounds Creek Watershed (LW15)
Mill Creek (1242200)
15.78 Miles
0 - 15.78
Natural Community
Natural communities (stream and lake natural communities) represent model results that use predicted flow and temperature based on landscape features and related assumptions. Ranges of flow and temperature associated with specific aquatic life communities (fish, macroinvertebrates) help biologists identify appropriate resource management goals. Wisconsin Natural Communities.
Coldwater, Cool-Cold Mainstem, Cool-Warm Mainstem
Year Last Monitored
This is the most recent date of monitoring data stored in SWIMS. Additional surveys for fish and habitat may be available subsequent to this date.
This river is impaired
Impairment Unknown
Total Phosphorus
Trout Water 
Trout Waters are represented by Class I, Class II or Class III waters. These classes have specific ecological characteristics and management actions associated with them. For more information regarding Trout Classifications, see the Fisheries Trout Class Webpages.
Outstanding or Exceptional 
Wisconsin has designated many of the state's highest quality waters as Outstanding Resource Waters (ORWs) or Exceptional Resource Waters (ERWs). Waters designated as ORW or ERW are surface waters which provide outstanding recreational opportunities, support valuable fisheries and wildlife habitat, have good water quality, and are not significantly impacted by human activities. ORW and ERW status identifies waters that the State of Wisconsin has determined warrant additional protection from the effects of pollution. These designations are intended to meet federal Clean Water Act obligations requiring Wisconsin to adopt an 'antidegradation' policy that is designed to prevent any lowering of water quality - especially in those waters having significant ecological or cultural value.
Impaired Water 
A water is polluted or 'impaired' if it does not support full use by humans, wildlife, fish and other aquatic life and it is shown that one or more of the pollutant criteria are not met.

Fish and Aquatic Life

Current Use
The use the water currently supports. This is not a designation or classification; it is based on the current condition of the water. Information in this column is not designed for, and should not be used for, regulatory purposes.
Fish and Aquatic Life - waters that do not have a specific use designation subcategory assigned but which are considered fishable, swimmable waters.
Attainable Use
The use that the investigator believes the water could achieve through managing "controllable" sources. Beaver dams, hydroelectric dams, low gradient streams, and naturally occurring low flows are generally not considered controllable. The attainable use may be the same as the current use or it may be higher.
Fish and Aquatic Life - waters that do not have a specific use designation subcategory assigned but which are considered fishable, swimmable waters.
Designated Use
This is the water classification legally recognized by NR102 and NR104, Wis. Adm. Code. The classification determines water quality criteria and effluent limits. Waters obtain designated uses through classification procedures.
Default FAL
Fish and Aquatic Life - Default Waters do not have a specific use designation subcategory but are considered fishable, swimmable waters.


Mill Creek is a tributary to the Wisconsin River at Tower Hill State Park. It is a Class II trout
stream for 4.5 miles of its length. One 4-mile section of trout water is downstream from Twin
Valley Lake, the other 0.5 mile stretch is downstream from the mouth of Trout Creek. Below
the last stretch of trout water, Mill Creek is considered a warm water sport fishery stream. A
rare aquatic species has been found in the creek in past surveys. The stream historically had
problems with flooding as a result of intensive agriculture and lumbering. Flood control
structures were put into place in the watershed to help lessen the problem. Two of these
structures formed Twin Valley and Cox Hollow Lakes in the upstream portion of Mill Creek.
These lakes are used primarily for fish, wildlife and recreational purposes. The creek below
the lakes and upstream from Trout Creek can have problems with cattle grazing and in-stream
sedimentation appears to be a problem.

From: Ripp, Coreen, Koperski, Cindy and Folstad, Jason. 2002. The State of the Lower Wisconsin River Basin.
PUBL WT-559-2002. Wisconsin Department of Natural Resources, Madison, WI.

Date  2002

Author  Cynthia Koperski

Historical Description

Mill Creek is a tributary to the Wisconsin River at Tower Hill State Park. It is a Class II
trout stream for 4.5 miles of its length (WDNR, 1980). Below the last atretch of trout
water it is considered a warm water sport fishery stream (Schlesser, 1991-1992). In-
stream sedimentation appears to be a problem (WDNR, 1991). There are areas of
excessive cattle grazing in the upper reaches of the stream between Trout Creek and
Twin Hollow Lake (WDNR, 1991)

Date  1994

Author   Surface Water Inventory Of Wisconsin

Historical Description

Mill Creek - Mouth location T8N R4E Section 20 -12, Gradient = 11.1 feet per mile, Total alkalinity = 240.0 mg/l, Volume of flow = 35.2 cfs.
The basic source of water of Mill Creek is springs on the Niagara escarpment of the Southwestern Uplands, but it also receives a considerable amount from runoff and ground seepage. Originally it began at springs in Cox Hollow (now Cox Hollow and Twin Valley Lakes) about 2.5 miles north of Dodgeville and flowed in a northeasterly direction to the Wisconsin River. The past history of this watershed shows that flooding was common and costly for farmers, the stream fishery, roads, and the soils of the basin. Pre-settlement times saw most of the watershed forested. The chief industry of early settlers, who moved into the area shortly after the Indian wars about the mid-nineteenth century, was lumbering.
Soon after, lumbering gave way to farming, first, in the form of wheat and then dairying. Cheese factories became common until modern transporation and refrigeration enabled milk to be safely transporated to distant markets. As of 1961 only one sawmill and four cheese factories remained. With the advent of intensive farming the choice land was cleared for crops and serious erosion followed. This was a common occurrence until recently when the Twin Parks Watershed plan was prepared by the Iowa Co. Soil Conservation District with the assistance of the USDA, USDI, and WDNR. The basic objectives of this plan included the installation of 10 floodwater structures and 4.5 miles of channel improvements. Eight of these are designed specifically for erosion control and three for fish and wildlife -Twin Valley, Birch, and Cox Hollow Lakes. Three others maintain a permanent pool deep enough to support a fishery but this is incidental to their primary purposes of flood control. Other works of improvement include land treatment measures such as contour farming and strip cropping, waterways, streambank protection and grade stabilization structures. The practices and structures completed to date have reduced severe flooding in this watershed. Some of the structures have reduced or eliminated the trout fishery in several tributary streams but the erosion control brought about by reduced flooding should enhance the fishery assets of the mainstream.
Principal tributaries include two of the best trout streams in the county in Love and Trout Creeks. Other streams of importance are Cutler, Ryan, and Hubbard Creeks. The total flow of these streams contributes about 56 percent of the base flow of Mill Creek. The most prized fishery in the watershed is for trout; however, the mainstream is managed for smallmouth bass and channel catfish. Other game fish species also present are largemouth bass, northern pike, rainbow trout and brown trout. Panfish include brown bullheads and bluegills. Forage and rough fish species include hornyhead
and creek chubs; redbelly and blacknose dace; stoneroller and fathead minnows; emeral shiners, carp, quillback carpsuckers, redhorse, white suckers, and sheepshead. There are at least 12 farm ponds in the watershed which support either largemouth bass-panfish or trout fisheries and are a major contributor to the overall fisheries resources of the area.
Aquatic game assets consist of ducks and beaver in lower sections and muskrats throughout its length.
Public access is available from Governor Dodge State Park but otherwise public lands are absent throughout the immediate drainage basin. Limited access is possible from 16 public road crossings.

From: Piening, Ronald and Threinen, C.W., 1968. Lake and Stream Classification Project. Surface Water Resources of Iowa County, Wisconsin Department of Natural Resources, Madison, WI.

Date  1968

Author   Surface Water Inventory Of Wisconsin

Mill Creek, Mill and Blue Mounds Creek Watershed (LW15) Fish and Aquatic LifeMill Creek, Mill and Blue Mounds Creek Watershed (LW15) RecreationMill Creek, Mill and Blue Mounds Creek Watershed (LW15) Fish Consumption

Impaired Waters

Mill Creek (1242200) from its mouth to CTH H was placed on the impaired waters list for total phosphorus in 2012. The 2016 assessments showed continued impairment by phosphorus; total phosphorus sample data exceed 2016 WisCALM listing criteria for the Fish and Aquatic Life use, however, available biological data do not indicate impairment (i.e. no macroinvertebrate or fish Index of Biotic Integrity (IBI) scored in the "poor" condition category). This water was also assessed for temperature and sample data did not exceed 2016 WisCALM listing criteria for the Fish and Aquatic Life use. Based on the most updated information, no change in existing impaired waters listing is needed.

Date  2015

Author  Aaron Larson


Wisconsin has over 84,000 miles of streams, 15,000 lakes and milllions of acres of wetlands. Assessing the condition of this vast amount of water is challenging. The state's water monitoring program uses a media-based, cross-program approach to analyze water condition. An updated monitoring strategy (2015-2020) is now available. Compliance with Clean Water Act fishable, swimmable standards are located in the Executive Summary of Water Condition in 2018. See also the 'monitoring and projects' tab.



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Management Goals

Wisconsin's Water Quality Standards provide qualitative and quantitative goals for waters that are protective of Fishable, Swimmable conditions [Learn more]. Waters that do not meet water quality standards are considered impaired and restoration actions are planned and carried out until the water is once again fishable and swimmable

Management goals can include creation or implementation of a Total Maximum Daily Load analysis, a Nine Key Element Plan, or other restoration work, education and outreach and more. If specific recommendations exist for this water, they will be displayed below online.


Monitoring the condition of a river, stream, or lake includes gathering physical, chemical, biological, and habitat data. Comprehensive studies often gather all these parameters in great detail, while lighter assessment events will involve sampling physical, chemical and biological data such as macroinvertebrates. Aquatic macroinvertebrates and fish communities integrate watershed or catchment condition, providing great insight into overall ecosystem health. Chemical and habitat parameters tell researchers more about human induced problems including contaminated runoff, point source dischargers, or habitat issues that foster or limit the potential of aquatic communities to thrive in a given area. Wisconsin's Water Monitoring Strategy was recenty updated.

Grants and Management Projects

Monitoring Projects

Watershed Characteristics

Mill Creek is located in the Mill and Blue Mounds Creek watershed which is 186.74 miĀ². Land use in the watershed is primarily forest (54.60%), grassland (20.40%) and a mix of agricultural (15.30%) and other uses (9.80%). This watershed has 382.87 stream miles, 106.91 lake acres and 6,596.99 wetland acres.

Nonpoint Source Characteristics

This watershed is ranked Medium for runoff impacts on streams, Low for runoff impacts on lakes and High for runoff impacts on groundwater and therefore has an overall rank of High. This value can be used in ranking the watershed or individual waterbodies for grant funding under state and county programs.However, all waters are affected by diffuse pollutant sources regardless of initial water quality. Applications for specific runoff projects under state or county grant programs may be pursued. For more information, go to surface water program grants.

Natural Community

Mill Creek is considered a Coldwater, Cool-Cold Mainstem, Cool-Warm Mainstem under the state's Natural Community Determinations.

Natural communities (stream and lake natural communities) represent model resultsand DNR staff valiation processes that confirm or update predicted conditions based on flow and temperature modeling from historic and current landscape features and related variables. Predicated flow and temperatures for waters are associated predicated fish assemblages (communities). Biologists evaluate the model results against current survey data to determine if the modeled results are corect and whether biological indicators show water quaity degradation. This analysis is a core component of the state's resource management framework. Wisconsin's Riverine Natural Communities.

Cool (Cold-Transition) Mainstem streams are moderate-to-large but still wadeable perennial streams with cold to cool summer temperatures. Coldwater fishes are common to uncommon, transitional fishes are abundant to common, and warm water fishes are uncommon to absent. Headwater species are common to absent, mainstem species are abundant to common, and river species are common to absent.

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