Mississippi Lake

Where Mississippi Lake is

Mississippi Lake lies in the County of Lanark, with shoreline in the Township of Beckwith, the Municipality of Mississippi Mills and the Township of Drummond/North Elmsley.

How deep is Mississippi Lake?

The deepest mapped contour on Mississippi Lake is 9.1 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 46 depth contours recorded during Ontario’s 1969 survey for Mississippi Lake.

See also Ontario's Largest and Deepest Lakes

Surveyed Depths

Ontario has surveyed the depths of several thousand of its lakes over more than half a century. Later surveys were conducted by boat with satellite positioning and produced hundreds of thousands of soundings per lake. Earlier surveys were charted by running transects across the water and drawing depth contours by hand.

Water quality

Ontario’s Lake Partner Program is a volunteer monitoring network. Participants collect water samples for phosphorus analysis and measure water clarity through the summer with a Secchi disk. Most sites are sampled for phosphorus once a year, in spring, and some several times a year between spring and fall. Phosphorus in many lakes rises through the summer, so the two kinds of average are measured on different bases.

Phosphorus is the nutrient that controls how much algae a lake can grow. A lake with little phosphorus stays clear and supports cold-water fish such as lake trout. As phosphorus rises, algae increase, the water clouds, and oxygen in the deep water falls as the algae decay. The province classifies each monitoring site by its average phosphorus:

• Oligotrophic, below 10 micrograms per litre: clear water and low algae.
• Mesotrophic, from 10 to 20: moderately productive water, with more algae and weed growth than an oligotrophic lake but rarely a bloom.
• Eutrophic, above 20: nutrient-rich water, prone to algal blooms and low oxygen at depth.

Mississippi Lake has 4 Lake Partner monitoring sites. Three have reported phosphorus for the three or more years the province requires before a status is assigned. All are classified mesotrophic.

The longest record is held by site 6996/4 at E end, Channel, with phosphorus sampled once a year over 13 years to 2018. Its long-term mean phosphorus concentration is 11.01 micrograms per litre, within the mesotrophic band, which runs from 10 to 20.

A Secchi disk is a white or black-and-white plate lowered on a marked line until it disappears from view. The depth at which it vanishes is the Secchi depth, a direct measure of water clarity. Clearer water gives a deeper reading.

The 13 clarity readings at site 6996/4 give a median Secchi depth of 3.3 meters.

Median Secchi depth by year at site 6996/4

See also Lake Water Quality and Blue-Green Algae in Ontario

Mississippi Lake Weather

The weather page for Mississippi Lake carries the forecast over the water, wave heights across the lake, and the modelled water temperature.

Mississippi Lake weather

Water temperature

Ontario’s aquatic resource records class Mississippi Lake as a warm-water lake, with a mean depth of 2.74 meters against its maximum of 9.1.

A lake separates into layers through the summer where it is deep enough. Sunlight and wind warm and mix the upper few meters, and beneath a band of rapid cooling, the thermocline, the water stays cold. A shallow lake mixes to the bottom instead and warms through, sooner in spring and later into autumn.

No provincial monitoring station records water temperature on Mississippi Lake. The LastLake model computes the temperature of its surface water for each day from the daily mean air temperature at Environment Canada’s Appleton climate station, 14 kilometers from the lake, or the next nearest station when its record is incomplete, and from the lake’s area of 2,437 hectares and its mean depth of 2.7 meters.

Each day’s figure carries the model’s typical error for that month on lakes of the same size. The figure in the chart below is the temperature near the surface, away from the shoreline. Bays, shallows and water deeper below the surface differ in temperature. Temperature is not measured when ice covers the lake. The weather page for Mississippi Lake carries the model’s figures for the past weeks and the coming week.

See also Lake Water Temperature in Ontario

Fish in Mississippi Lake

Ontario’s aquatic resource records name 29 fish species in Mississippi Lake.

Popular species in the province’s records

• Northern Pikepike
• Walleyeperch
• Yellow Perchperch
• Smallmouth Basssunfish
• Largemouth Basssunfish
• Black Crappiesunfish
• Rock Basssunfish
• Pumpkinseedsunfish
• Bluegillsunfish
• Burbotcod
• Brown Bullheadcatfish

Spawning areas

Ontario maps 15 fish spawning records within the Mississippi Lake outline, for four different species, and all of them are mapped below. Every record is recorded as verified and presently suitable, and none is classed as sensitive.

By number of records

By area mapped

• Northern Pike6 areas6.0 ha
• Walleye5 areas1.9 ha
• Smallmouth Bass2 areas0.5 ha
• Largemouth Bass2 areas2.5 ha

The federal Fisheries Act prohibits the harmful alteration, disruption or destruction of fish habitat without an authorization, so a dock, dredging, infill or shoreline work at a mapped spawning area is reviewed on that basis.

Stocking history

Ontario’s stocking records for Mississippi Lake run from 1946 to 1979 and hold 54 releases. Walleye account for most of the fish: 27,300,000 released in 23 of the years between 1946 and 1979. The last recorded release was 1,000,000 walleye eggs in 1979.

The province’s record of stocking for recreational fishing, kept from 2016, lists no release into Mississippi Lake.

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for eleven species taken from Mississippi Lake, tested for contaminants at a sampling location in Drummond Twp., Lanark Co. Each figure below is the most meals a month the guide advises for a fish of that length. Where mercury sets the advice, the figure falls as the fish gets longer, because mercury accumulates over a fish’s life. A zero means the guide advises no meals of that fish at that size.

General population: adultsSensitive population: children under fifteen, women who are or may become pregnant

Fisheries Management Zone 18

Mississippi Lake lies in Fisheries Management Zone 18. Ontario sets its fishing seasons and catch limits by zone.

Fisheries management zones around Mississippi Lake

See also Fishing Seasons in Ontario, Zone by Zone and Fish Stocking in Ontario Lakes

Mississippi Lake Ice Fishing

An ice hut on Mississippi Lake must be removed by March 15. The province sets dates for ice hut removal as a safety measure to ensure huts are removed before thawing occurs. One date applies to an entire fisheries management zone (FMZ). Mississippi Lake lies within FMZ 18.

An ice hut must also be removed before the ice breaks up, whether or not that date has passed. The deadline clears huts from the ice ahead of the thaw and does not close the fishing season.

Registration is required in FMZ 18 for an ice hut built of anything other than fabric, and for a fabric tent covering seven square meters or more. Registration is free, and the number is displayed on the outside of the hut.

Ice conditions

No public record reports the thickness or the condition of the ice on Mississippi Lake on any given day. Ontario publishes ice safety guidance for anyone going out on the ice, at ontario.ca.

See also Lake Ice in Ontario and When the Lakes Will Freeze This Winter

Getting on the water

One access mark is mapped on Mississippi Lake.

See also Boat Launches on Ontario Lakes

Islands and names

Mississippi Lake contains fifteen islands in the Ontario Hydro Network’s outline, zero of them over 10 hectares and five under a tenth of a hectare.

Official names

Ontario’s geographic names register lists 32 official names on the water and its islands: 14 islands, fourteen bays and one point on an island. A further 17 named points stand on the mainland shore.

Bays 14

• Black Bass Bay
• Code Bay
• Duff Bay
• Ebbs Bay
• Flintoft Bay
• Hunters Bay
• Kinch Bay
• Kings Bay
• Mallochs Bay
• McEwen Bay
• McGibbon Bay
• Osborne Bay
• Potato Bay
• Pretties Bay

Points on the shore 17

• Anchor Point
• Birch Point
• Black Point
• Brown Point
• Dixon Point
• Ebbs Point
• Father Point
• Grasshopper Point
• Ikwe Point
• McGibbon Point
• McNaughton Point
• Norway Point
• Pickerel Point
• Poole Point
• Robertson's Point
• Rocky Point
• Two Oaks Point

Communities on the lake 6

• Lake Park
• Petrie Shore
• Tennyson
• Ebbs Shore
• McCulloughs Landing
• Innisville

Nearby lakes

• Dalhousie Lake32 km away
• Otter Lake32 km away
• Big Rideau Lake33 km away
• Christie Lake35 km away

All lakes

Questions about Mississippi Lake

• How deep is Mississippi Lake?

  Its deepest charted contour is 9.1 meters, and the water within it is deeper.

• How big is Mississippi Lake?

  Its surface covers 24.4 square kilometers and it holds 15 islands. Of its 66 kilometers of shoreline, 62 kilometers is the mainland shore and 4 kilometers is the shore of the islands.

• What fish are in Mississippi Lake?

  Ontario’s aquatic resource records name 29 species, among them walleye, smallmouth bass, largemouth bass, northern pike, yellow perch and black crappie.

• Is the water clear?

  All three monitoring sites with a phosphorus status are classified mesotrophic, the middle of the province’s three bands.

• Is there a public boat launch?

  No boat launch on Mississippi Lake is marked in the records this page draws on.