Twin Valley Lake, Mill and Blue Mounds Creek Watershed (LW15)
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Twin Valley Lake (1245800)
135.92 Acres
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.
Reservoir
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.
2024
Excellent
 
This is impaired
Excess Algal Growth
Unknown Pollutant
 
Iowa
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.
No
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.
No
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.
Yes

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.
Deep Lowland
Deep lowland lake describes the depth and location of the lake in a watershed. These variables affect the lakes response to watershed variables.
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.
Default FAL
Fish and Aquatic Life - Default Waters do not have a specific use designation subcategory but 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.
Cold
Streams capable of supporting a cold water sport fishery, or serving as a spawning area for salmonids and other cold water fish species. Representative aquatic life communities, associated with these waters, generally require cold temperatures and concentrations of dissolved oxygen that remain above 6 mg/L. Since these waters are capable of supporting natural reproduction, a minimum dissolved oxygen concentration of 7 mg/L is required during times of active spawning and support of early life stages of newly-hatched fish.

Overview

Twin Valley Lake is located in Iowa County just below Cox Hollow Lake and is an
impoundment on the headwaters of Mill Creek. The lake is 152 acres with a maximum depth
of 32 feet. The lake is located wholly inside of Governor Dodge State Park and was
constructed in 1967 for wildlife habitat, recreation and as a flood control structure. The
fishery of Twin Valley Lake is musky walleye, largemouth bass, panfish and trout.
Monitoring on Twin Valley Lake began in 2001.

Date  1999

Author   Aquatic Biologist

Historical Description

Source: 1968, Surface Water Resources of Iowa County,WI: WI-DNR Twin Valley Lake, T67N, R34E, Sections 1, 2, 11, 35, 36

Twin Valley Lake is an impoundment of Mill Creek just below Cox Hollow Lake in the 4,600 acre of Governor Dodge State Park. The dam was constructed in 1965-66 as part of the Twin Parks Watershed Project sponsored by the Federal Government and the lake was created in early 1967. Most of the water is received from Mill Creek and several small tributaries; however, there are also a number of large springs in the basin. Most of the watershed was farmed until recently and has since been allowed to revert to its natural state. This has provided more stable land cover. The Bureau of Research has included this lake in its impoundment studies. The fishery consists of species of fish which were present in the stream before it was impounded. Some of these were received from Cox Hollow Lake. Gamefish which are common include largemouth bass, northern pike, and brown trout. Panfish include bluegills, crappies, and bullheads. Forage species which are present include white suckers, bluntnose minnows, common shiners, creek chubs and hornyhead chubs. Aquatic game assets consist of muskrats which are abundant and possibly some beaver. Waterfowl consist of most species commonly found in Wisconsin and include mallards, blue-winged teal, coots and Canada geese. The greatest variety is present during the spring and fall migrations. Since it is located in a state park, access is adequate. A large launching site with ample parking has been constructed. Campgrounds and a swimming beach are planned to expand the recreational facilities.

Surface Acres = 145, S.D.F. = 1.8, Maximum depth = 35 feet

Date  1968

Author   Surface Water Inventory Of Wisconsin

Twin Valley Lake, Mill and Blue Mounds Creek Watershed (LW15) Fish and Aquatic LifeTwin Valley Lake, Mill and Blue Mounds Creek Watershed (LW15) RecreationTwin Valley Lake, Mill and Blue Mounds Creek Watershed (LW15) Fish Consumption

General Condition

Governor Dodge State Park Twin Valley Beach was assessed for the 2018 listing cycle; E. coli data sample data were clearly below the 2018 WisCALM listing thresholds for the Recreation use. This beach was meeting this designated use and was not considered impaired.

Date  2017

Author  Ashley Beranek

Impaired Waters

Twin Valley Lake (WBIC 1245800) was placed on the impaired waters list for excess algal growth in 2016. The 2018 assessments showed continued excess algal growth; new chlorophyll-a sample data exceeded the 2018 WisCALM listing thresholds for the Recreation use. Based on the most updated information, no change in the existing impaired waters listing was needed.

Date  2017

Author  Ashley Beranek

Impaired Waters

Twin Valley Lake (WBIC 1245800) was assessed during the 2016 listing cycle; chlorophyll sample data exceed 2016 WisCALM listing thresholds for the Recreation use, however, total phosphorus data do not exceed REC thresholds. Total phosphorus and chlorophyll data do not exceed Fish and Aquatic Life thresholds.

Date  2015

Author  Aaron Larson

Condition

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.

Reports

2020 Comprehensive WQ Assessments
2018 List of Healthy (Category 2) Waters
Final Draft 2018 Impaired Waters List
Final Assessment Data from TSI Package and Assessment Units 2018
Comprehensive 2018 Lake/Impoundment Water Quality Assessments
AEPP48616_Final Report [South AIS Control]
Comprehensive 2016 Lake Reservoir Assessments
AIS Early Detection 2015 Data Form Twin Valley 1245800
Comprehensive 2014 TP Lakes Assessment
Twin Valley (Iowa) Curly-leaf pondweed 2011
Twin Valley (Iowa) Eurasian water-milfoil 2011
Twin Valley Lake, Iowa County - Aquatic Plant Sampling Map (1)(40 mpts)
Twin Valley Lake, Iowa County - Aquatic Plant Sampling Map (2)(40 mpts)
Twin Valley Lake, Iowa County - Aquatic Plant Sampling Map (40 mpts)
Twin Valley Lake, Iowa County - Garmin Text File
Twin Valley Lake Management Plan (2004)
Lake Bathymetry Map for Twin Valley Lake

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

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

Project Name (Click for Details)Year Started
SOUTHWEST BADGER R C & D: Southwest Badger RC&D- Twin Valley Lake2016
SOUTHWEST BADGER R C & D: Twin Valley 2015 Clean Boats Clean Waters Project2015

Monitoring Projects

WBICOfficial Waterbody NameStation IDStation NameEarliest Fieldwork DateLatest Fieldwork DateView StationView Data
1245800Twin Valley Lake10018030Twin Valley Lake -- Launch5/6/20061/23/2018MapData
1245800Twin Valley Lake253201Twin Valley Lake - Govenor Dodge State Park Beach6/3/20038/26/2024MapData
1245800Twin Valley Lake10002729Twin Valley Lake6/1/19899/30/2017MapData
1245800Twin Valley Lake10015109Twin Valley Lake Baseline8/7/20148/7/2014MapData
1245800Twin Valley Lake253127Twin Valley Lake - Deep Hole8/13/20014/10/2024MapData

Watershed Characteristics

Twin Valley Lake is located in the Mill and Blue Mounds Creek watershed which is 186.74 mi². 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

Twin Valley Lake is considered a Reservoir under the state's Natural Community Determinations.

Natural communities (stream and lake natural communities) represent model results and 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.

Fisheries & Habitat

The Bureau of Research has included this lake in its impoundment studies. The fishery consists of species of fish which were present in the stream before it was impounded. Some of these were received from Cox Hollow Lake. Gamefish which are common include largemouth bass, northern pike, and brown trout. Panfish include bluegills, crappies, and bullheads. Forage species which are present include white suckers, bluntnose minnows, common shiners, creek chubs and hornyhead chubs. Aquatic game assets consist of muskrats which are abundant and possibly some beaver. Waterfowl consist of most species commonly found in Wisconsin and include mallards, blue-winged teal, coots and Canada geese. The greatest variety is present during the spring and fall migrations.

Date  2011

Author   Aquatic Biologist