Prairie Brook, Lower East Branch Pecatonica Rivers Watershed (SP03)
Prairie Brook, Lower East Branch Pecatonica Rivers Watershed (SP03)
Prairie Brook (901500)
3.11 Miles
0 - 3.11
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's Riverine Natural Communities.
Coldwater, Cool-Cold Headwater
Year Last Monitored
This is the most recent date of water monitoring stored in the SWIMS system. Additional surveys for fish and habitat may be available subsequent to this date.
This river is impaired
Degraded Habitat
Sediment/Total Suspended Solids
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.
Class III Trout
Streams capable of supporting a seasonal coldwater sport fishery and which may be managed as coldwater streams.
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.


This small steep stream drains an unglaciated valley and serves as a tributary to Dougherty Creek. The stream is valuable because it provides a source of cold water to Dougherty Creek (SurfaceWater Resources of Green Co, 1980). Heavily pastured, it suffers from streambank erosion; however the steep gradient maintains a sandy bottom with small amounts of gravel and cobble. Prairie Brook is a Class III trout stream whose potential is somewhat limited by flow. In (what year?) the Prairie Brook was added to the state’s list of impaired waters. The department and the Green County Land and Water Conservation Department should work with landowners to install best management practices and enforce NR151 to improve the riparian corridor of the stream. The stream was stocked with brook trout in 2005. It has not been monitored recently.

Date  2010

Author  James Amrhein


This two-mile long creek originates in western Green County and flows westward to Dougherty Creek. Prairie Brook Creek runs primarily through pasture and there is a considerable amount of bank erosion. However, the steep gradient of the stream maintains a sandy bottom with small amounts of gravel and cobble, as well as "good" width:depth ratio (8:1). A macroinvertebrate assessment in 1990 described the water quality of this stream as "very good" with slight organic pollution (HBI = 3.636). Prairie Brook is currently classified as Class III trout stream (no evidence of natural reproduction) but is potentially a Class II. Fish monitoring conducted in 2002 recovered only two species (creek chub and brook stickleback) and a cold water index of biotic integrity was calculated as "poor". Habitat is very limited and fencing to prevent over pasturing would help improve the stream corridor.

Date  2005

Author   Aquatic Biologist

Historical Description

Draining an unglaciated valley, this small, steep trout stream flows westward to Dougherty Creek. Running primarily through pasture, it experiences considerable bank erosion, howev,er the steep gradient maintains a sandy bottom with small amounts of gravel and rubble. The water is usually clear. Prairie Brook is fed by runoff, one spring-fed tributary, and two springs, one of which has been impounded for a private fishing pond. This stream is valuable because it provides a source of clear, cold water to Dougherty Creek, another trout

All of Prairie Brook is managed for brown trout, with the lower half being Class II and the remainder Class I] Small flow prevents the establishment of a sustained trout fishery and there is almost a complete annual harvest of trout by fishermen. Therefnre, fnrage fish are generally much more abundant than trout. Wildlife values are very low because of the stream's small size and a deficiency of adjacent wetlands. Public access and frontage consists of two town road crossings.

Fish Species: Brown trout, common shiner, redbelly dace unspecified, creek chub, white sucker, brook stickleback. Euddledock Hollow

Bush, D.M., R. Cornelius, D. Engle, and C.L. Brynildson. 1980. Lake and Stream Classification Project. Surface Water Resources of Green County, 2nd Edition. Wisconsin Department of Natural Resources, Madison, Wisconsin.

Surface Acres = 0.7, Length = 2.0 Miles, Gradient = 70 ft./mi., Base Discharge = 2.7 cu. ft./sec.

Date  1980

Author   Surface Water Inventory Of Wisconsin

Prairie Brook, Lower East Branch Pecatonica Rivers Watershed (SP03) Fish and Aquatic LifePrairie Brook, Lower East Branch Pecatonica Rivers Watershed (SP03) RecreationPrairie Brook, Lower East Branch Pecatonica Rivers Watershed (SP03) Fish Consumption


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 2016 . See also 'monitoring' and 'projects'.


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

Prairie Brook is located in the Lower East Branch Pecatonica Rivers watershed which is 144.80 miĀ². Land use in the watershed is primarily grassland (44.90%), agricultural (35.10%) and a mix of forest (16%) and other uses (3.90%). This watershed has 370.96 stream miles, 107.68 lake acres and 2,029.49 wetland acres.

Nonpoint Source Characteristics

This watershed is ranked Not Available for runoff impacts on streams, Not Available 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.This water is ranked High Stream for individual Rivers based on runoff problems and the likelihood of success from project implementation.

Natural Community

Prairie Brook is considered a Coldwater, Cool-Cold Headwater 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) Headwaters are small, usually perennial streams with cold to cool summer temperatures. Coldwater fishes are common to uncommon (<10 per 100 m), transitional fishes are abundant to common, and warm water fishes are uncommon to absent. Headwater species are abundant to common, mainstem species are common to absent, and river species are absent.

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