LAKE MINNETONKA WATER QUALITY GUIDE
Lake Minnetonka is a unique body of water because each of its forty-two bays varies in depth, surface area, and water quality. What reads as one lake on a map behaves as dozens of distinct environments, and for a buyer that variation directly affects swimming, boating, clarity, and the feel of a shoreline. This guide explains how the bays are graded and walks through each one so you can understand the water in front of a property before you fall for the view.
The Minnehaha Creek Watershed District (MCWD) began its water quality grading method in 1989. Three core measurements combine to indicate the quality of a bay, while additional factors such as precipitation, aquatic plants, fisheries, harmful chemicals, and over-use also shape the result. The MCWD uses these grades to compare waters within the same region. Because the letter grades reflect long-term monitoring rather than a single day on the water, treat them as a guide to a bay's general character and confirm current-season conditions with the MCWD before relying on them.
THE 3 WATER QUALITY MEASUREMENTS:
- TP is the abbreviation of total phosphorus. Total phosphorus is usually a limiting nutrient for algae and plants. An increase in total phosphorus relates closely to increased algae, a higher frequency of algal blooms, and a greater quantity of blue-green algae.
- CHL-A is the abbreviation of chlorophyll-a. Chlorophyll-a is the green pigment in algae and plants that is essential to photosynthesis, and measuring it in the water estimates algal abundance.
- SD is the abbreviation of Secchi disk depth, or water clarity. The deeper the Secchi disk stays visible, the clearer the water.
THE GRADE DISTRIBUTION IS BROKEN DOWN INTO LETTERS A THROUGH F:
- A: a relative ranking of 90% clarity and up. Bays with this distinction are in the top 10% of the cleanest bays on Lake Minnetonka. They are often described as crystal clear and beautiful, are exceptional, and can be enjoyed recreationally without hesitation.
- B: a relative ranking between 70% and 90% clarity. Generally good quality, though algae may limit swimming toward the end of summer.
- C: a relative ranking between 30% and 70% clarity. Average quality, where swimming, boating, and fishing may become less desirable relatively early in the season, and algae blooms occasionally.
- D: a relative ranking between 10% and 30% clarity. These bays have severe algae problems, and recreation is generally limited.
Explore below to learn more about the water quality in your favorite Lake Minnetonka bay.
BLACK LAKE
The maximum water depth in Black Lake is 27 feet, with a C water quality rating from the Minnehaha Creek Watershed District.
BROWNS BAY
The water depth in Browns Bay ranges from 10 to 80 feet, with an A rating from the Minnehaha Creek Watershed District.
CARMAN BAY
Carman Bay has a maximum water depth of 20 feet, and the Minnehaha Creek Watershed District classifies its water quality as an A. The water is crystal clear and can be enjoyed year-round. The city of Orono actively works to keep Carman Bay clean through the Carman Bay Lake Improvement District (CBLID), which improves water quality and targets invasive species. That effort has already reduced invasive species in the bay while increasing native species.
CARSONS BAY
Carsons Bay has a maximum water depth of 29 feet, and the Minnehaha Creek Watershed District rates its water quality an A.
COFFEE COVE
The Minnehaha Creek Watershed District rates Coffee Cove a C in water quality.
COOKS BAY
Cooks Bay has a maximum water depth of 43 feet, and the Minnehaha Creek Watershed District rates its water quality a B.
CRYSTAL BAY
Allen French, an early settler, named Crystal Bay for the crystal clear water that mirrors the sky above. The name stuck, and the Minnehaha Creek Watershed District reaffirms French's impression with an A in water quality. At a maximum depth of 113 feet, it is the deepest bay on Lake Minnetonka.
EAST UPPER LAKE
East Upper Lake has a maximum water depth of 48 feet, and the Minnehaha Creek Watershed District gives it a B in water quality.
ECHO BAY
The maximum water depth in Echo Bay is 20 feet, and the Minnehaha Creek Watershed District rates the bay an A in water quality.
EMERALD LAKE
The Minnehaha Creek Watershed District rates Emerald Lake a C in water quality.
EXCELSIOR BAY
The water depth in Excelsior Bay ranges from 4 to 35 feet, with an A rating from the Minnehaha Creek Watershed District.
FOREST LAKE BAY
The maximum water depth in Forest Lake Bay is 30 feet, and the Minnehaha Creek Watershed District assigns the bay a C rating in water quality.
GIDEON BAY
Gideon Bay has a maximum water depth of 57 feet, and the Minnehaha Creek Watershed District rates the bay an A in water quality.
GRAYS BAY
The water depth in Grays Bay ranges from 5 to 30 feet, and the Minnehaha Creek Watershed District rates it an A for water quality.
HALSTED BAY
Halsted Bay has a maximum water depth of 36 feet, and the Minnehaha Creek Watershed District rates it a C for water quality.
HARRISONS BAY
The water depth in Harrisons Bay ranges from 4 to 30 feet, and the Minnehaha Creek Watershed District rates the bay a C for water quality.
JENNINGS BAY
Jennings Bay has a maximum water depth of 26 feet, and the Minnehaha Creek Watershed District rates the bay a C for water quality.
LAFAYETTE BAY
The water depth in Lafayette Bay ranges from 5 to 57 feet, with an A rating from the Minnehaha Creek Watershed District.
LIBBS LAKE
The water depth in Libbs Lake ranges from 2 to 8 feet, with a B rating from the Minnehaha Creek Watershed District.
LOST LAKE BAY
Lost Lake Bay has an abundance of cattails and reeds, which help keep Lake Minnetonka clean by filtering surface runoff. The maximum depth is only 3 feet, and the Minnehaha Creek Watershed District rates it a C in water quality.
LOWER LAKE SOUTH
The water depth in Lower Lake South ranges from 5 to 80 feet, and the Minnehaha Creek Watershed District rates the bay an A in water quality.
MAXWELL BAY
The maximum water depth in Maxwell Bay is 43 feet, and the Minnehaha Creek Watershed District rates Maxwell Bay a B in water quality.
NORTH ARM BAY
The maximum water depth in North Arm Bay is 60 feet, and the Minnehaha Creek Watershed District rates North Arm Bay a B in water quality.
NORTH LOWER LAKE EAST
The water depth in North Lower Lake East ranges from 12 to 51 feet, with an A rating from the Minnehaha Creek Watershed District.
NORTH LOWER LAKE WEST
The water depth in North Lower Lake West ranges from 10 to 80 feet, with an A rating from the Minnehaha Creek Watershed District.
OLD CHANNEL BAY
The water depth in Old Channel Bay ranges from 5 to 51 feet, with a B rating from the Minnehaha Creek Watershed District.
PEAVY LAKE
Peavy Lake reaches a maximum depth of 63 feet, and the Minnehaha Creek Watershed District rates it a C in water quality.
PHELPS BAY
The maximum water depth in Phelps Bay is 30 feet, with a B rating from the Minnehaha Creek Watershed District.
PRIESTS BAY
The maximum water depth in Priests Bay is 46 feet, with a C rating from the Minnehaha Creek Watershed District.
ROBINSON BAY
The maximum water depth in Robinson Bay is 70 feet, with an A rating from the Minnehaha Creek Watershed District.
SETON LAKE
The maximum water depth of Seton Lake is 25 feet, with a C rating from the Minnehaha Creek Watershed District.
SMITHS BAY
The maximum water depth in Smiths Bay is 80 feet, with an A rating from the Minnehaha Creek Watershed District.
SMITHTOWN BAY
The maximum water depth in Smithtown Bay is 80 feet, and the bay has an A rating from the Minnehaha Creek Watershed District.
SOUTH UPPER LAKE
The maximum depth of South Upper Lake is 84 feet, with a B rating from the Minnehaha Creek Watershed District.
SPRING PARK BAY
The maximum water depth of Spring Park Bay is 36 feet, with an A rating from the Minnehaha Creek Watershed District.
ST. ALBANS BAY
The maximum water depth of St. Albans Bay is 32 feet, with an A rating from the Minnehaha Creek Watershed District.
ST. LOUIS BAY
The maximum water depth of St. Louis Bay is 38 feet, with an A rating from the Minnehaha Creek Watershed District.
STUBBS BAY
The maximum water depth of Stubbs Bay is 38 feet, with a C rating from the Minnehaha Creek Watershed District.
TANAGER LAKE
Tanager Lake reaches a maximum depth of 20 feet, and the Minnehaha Creek Watershed District rates the bay a C in water quality.
WAYZATA BAY
Wayzata Bay reaches a maximum depth of 87 feet, and the Minnehaha Creek Watershed District rates the bay an A in water quality.
WEST ARM
West Arm reaches a maximum depth of 32 feet, and the Minnehaha Creek Watershed District rates the bay a C in water quality.
WEST UPPER LAKE
West Upper Lake reaches a maximum depth of 66 feet, and the Minnehaha Creek Watershed District rates the bay a B in water quality.
IMPROVING LOW-WATER-QUALITY LAKE GRADES
Raising a bay's grade takes work. It can mean changes to drainage patterns, filtration, or stormwater detention, and not every bay has the same ceiling for improvement, since a shallow bay can only ever offer so much Secchi disk visibility. Everyone plays a role. A home and yard can quietly contribute to a neighborhood bay's decline, so keeping pet waste, leaves, chemicals, and runoff out of storm drains helps keep the water clean. The LMCD publishes a lakeshore owner guide that answers common questions and supports the transition to a lake-friendly lifestyle and cleaner water.
Specializing in the homes, lakeshore, lifestyle and history of Lake Minnetonka.Meet Dan Hollerman
Source: Minnehaha Creek Watershed District ®
Source: Lake Minnetonka Water Depth Map, Minnehaha Creek Watershed District ®
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