Otter Lake

Where Otter Lake is

Otter Lake lies in the United Counties of Leeds and Grenville, within the Township of Rideau Lakes.

How deep is Otter Lake?

The deepest mapped contour on Otter Lake is 36.6 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 90 depth contours for Otter 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.

Otter 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. Two of those sites are classified oligotrophic and one mesotrophic.

The longest record is held by site 4187/1 at Mid Lake, deep spot, with phosphorus sampled once a year over 16 years to 2025. Its long-term mean phosphorus concentration is 10.39 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 37 clarity readings at site 4187/1 give a median Secchi depth of 4.9 meters.

Median Secchi depth by year at site 4187/1

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

Fish in Otter Lake

Ontario’s aquatic resource records name 16 fish species in Otter Lake. The province’s other records for the lake name one further species, lake trout. It appears in the records below.

Popular species in the province’s records

• Brook Trouttrout and whitefish
• Rainbow Trouttrout and whitefish
• Ciscotrout and whitefish
• Northern Pikepike
• Yellow Perchperch
• Smallmouth Basssunfish
• Largemouth Basssunfish
• Rock Basssunfish
• Pumpkinseedsunfish
• Bluegillsunfish
• Burbotcod
• Brown Bullheadcatfish

Spawning areas

Ontario maps 18 fish spawning records within the Otter Lake outline, for two different species, and all of them are mapped below.

By number of records

By area mapped

• Smallmouth Bass12 areas11.0 ha
• Northern Pike6 areas1.9 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 Otter Lake run from 1946 to 2005 and hold 87 releases. Rainbow Trout account for most of the fish: 108,801 released in ten of the years between 1953 and 2005. The last recorded release was 15,741 rainbow trout fingerlings in 2005.

Fisheries Management Zone 18

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

Fisheries management zones around Otter Lake

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

Otter Lake Ice Fishing

An ice hut on Otter 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). Otter 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 Otter 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

Islands and names

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

Nearby lakes

• Big Rideau Lake8 km away
• Upper Beverley Lake19 km away
• Newboro Lake23 km away
• Christie Lake25 km away

All lakes

Questions about Otter Lake

• How deep is Otter Lake?

  Its deepest charted contour is 36.6 meters, and the water within it is deeper.

• How big is Otter Lake?

  Its surface covers 5.7 square kilometers and it holds 13 islands. Of its 23 kilometers of shoreline, 19 kilometers is the mainland shore and 4 kilometers is the shore of the islands.

• What fish are in Otter Lake?

  Ontario’s aquatic resource records name sixteen species, among them smallmouth bass, largemouth bass, northern pike, yellow perch and brook trout. The lake’s spawning, consumption and stocking records also name lake trout.