Milwaukee River, Milwaukee River South Watershed (MI02)
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Milwaukee River, Milwaukee River South Watershed (MI02)
Milwaukee River (15000)
9.98 Miles
19.35 - 29.33
Natural Community
Warm Mainstem
Year Last Monitored
2025
Good
 
This river is impaired
Recreational Restrictions - Pathogens, PCBs Contaminated Fish Tissue
E. coli, PCBs
 
Ozaukee
Trout Water 
No
Outstanding or Exceptional 
No
Impaired Water 
Yes

Fish and Aquatic Life

Current Use
Supported Aquatic Life
Attainable Use
WWFF
Designated Use
WWSF

Overview

For assessment purposes the Milwaukee River is segmented into five assessment units (AUs): from the mouth at the Kinnickinnic River upstream to North Ave Dam (miles 0 to 2.9); North Ave Dam to Thiensville Dam (miles 2.9 to 19.35); Thiensville Dam to Lime Kiln Dam (miles 19.35 to 29.33); Lime Kiln Dam to Gadow Mill Dam in West Bend (miles 29.33 to 68.5); and Gadow Mill Dam in West Bend to the headwaters (miles 68.5 to 103.34). The entire river has pollutants identified. The 2018 Milwaukee River Basin TMDL addresses phosphorus and bacteria listings.

Date  2022

Author  Ashley Beranek

Overview

The Milwaukee River is the major waterway of the county. All of the larger towns, with the exception of Port Washington and Cedarburg are on the river, indicating its importance in the past for transportation and power. There are five dams on the river, two of which still supply power for private use. Flow of the river, as measured at Milwaukee, has ranged from a low of 2.6 cfs to 14,300 cfs. The average has been 387 cfs.

Northern pike, smallmouth bass, walleyes, channel catfish and panfish are the main species of fish. Two areas, Fredonia to Saukville and Grafton to Thiensville, have fishable numbers of smallmouth bass. Pollution and fluctuating water levels are the main management problems.

Also associated with P. filiformis was P. gramineus and P. robbinsii. It was observed that for some distance below towns, vegetation is limited to scattered areas of P. filiformis and massive growth of filamentous algae (Cladophora). Then rooted vegetation increases to include all of the above species in dense stands. Water color could be correlated also with increasing transparency where the vegetation increased. This was assumed to be within the recovery zone.

Milwaukee River T9N, R21E, Section 36, Surface Acres = 590.5, Length = 34.8 miles, Gradient = 4.4 feet per mile.

From: Poff, Ronald J., Gernay, Ronald, and Threinen, C.W., 1964. Surface Water Resources of Ozaukee County:
Lake and Stream Classification Project. Wisconsin Conservation Department, Madison, WI.

Date  1964

Author   Aquatic Biologist

Historical Description

On June 12 and 16, 1964, 34.8 miles of the Milwaukee River were traversed
by canoe from County Trunk "A" in Washington County through Ozaukee County to the Ozaukee and Milwaukee County border to evaluate navigability, vegetation, bottom types, water color, and basic fertility of the Milwaukee River in Ozaukee County. Water stage was low at the time.

Navigability ranged from excellent to difficult due to the presence of boulders, gravel bars, and dolomitic rock outcrops. All stretches that are navigable by outboard craft are included on the map. Navigation is excellent by canoe from Grafton to the second dam downstream. Larger craft are limited to the segment one and one-half miles above County Trunk "M" to Thiensville. Large craft are otherwise confined to the five impoundments. The segment from Grafton to the second dam downstream flows through an area of high, partially wooded dolomite bluffs giving it a significant scenic value. Vegetation patterns are not diverse. Potamageton filiformis seemed to be the dominant aquatic plant and was observed the entire length of the river except in impoundments and immediately downstream from cities which contribute treated sanitary effluent.

Bottom materials ranged from solid dolomite rock to sand. Gravel and sand
in equal proportions constitute the bottom except on bedrock exposures and in impoundments. Silting is not a problem and significant amounts were noted only in t w regions, in Saukville and from County Trunk "M" to Thiensville, Of special note is the Waubakee formation which is exposed north of Waubeka. This thin shelved dolomitic rock forms about three-fourths of a mile of ledges with shallow water which necessitated portaging. The region from Grafton to the second dam also is exposed bedrock.

The region from Waubedonia Park downstream, approximately two miles, constitutes the most rubble strewn segment with boulders of all sizes present. This area also gave navigational difficulty with the low water levels encountered at the time. Water color remained clear until one mile above Waubeka where it turned from clear to light brown. Fertility as measured by specific conductance and methyl orange alkalinity showed that in general, conductance increased while alkalinity decreased.

This can be interpreted to mean that calcium and magnesium ions decreased or stayed the same while other ions such as sodium, sulphates and chlorides increased raising the conductance. This is to be expected since these ions are common in effluent from villages along the river. Numerous dead fish were observed especially downstream from the dams. These were almost entirely white suckers. This may have indicated poor water conditions. An evaluation of the fishery was not attempted but carp were observed to be present the entire length with the largest numbers upstream from Saukville.

Fishermen at the Waubeka Dam stated that northern pike, largemouth bass, bluegills, green sunfish, bullheads (spp.), smallmouth bass and an occasional walleye are caught. No attempt was made to differentiate the minnow species but minnows were abundant through the entire area covered. Below Grafton and Thiensville several fish were observed to have "sewage sickness". The typical specimen was lethargic, drifted along near the surface, and was commonly afflicted with fungus growths several places on its body. The number of these fishes was not significant.

From: Poff, Ronald J., Gernay, Ronald, and Threinen, C.W., 1964. Surface Water Resources of Ozaukee County:
Lake and Stream Classification Project. Wisconsin Conservation Department, Madison, WI.

Date  1964

Author   Aquatic Biologist

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.
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.
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.
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.
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.
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.
Waters that support fish and aquatic life communities (healthy biological communities).
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.
Streams capable of supporting a warm waterdependent forage fishery. Representative aquatic life communities associated with these waters generally require cool or warm temperatures and concentrations of dissolved oxygen that do not drop below 5 mg/L.
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.
Streams capable of supporting a warm waterdependent sport fishery. Representative aquatic life communities associated with these waters generally require cool or warm temperatures and concentrations of dissolved oxygen that do not drop below 5 mg/L.