How deep is Big Lake?

Big Lake reaches a maximum depth of 81 feet in the Michigan DNR Inland Lake Contours survey. Most of it is far shallower: the survey charts 9 closed depth contours over about 125 acres, and half of that water sits inside the 40 ft line. The 81 ft figure is a single recorded sounding rather than a closed contour, so the deepest line you can actually trace on the map is 80 ft.

Where is the deepest part of Big Lake?

The deepest charted water on Big Lake lies inside the 80 ft contour, toward the northwestern corner of the lake. That contour encloses under an acre, under 1% of the mapped water, so it is a small target on a small water, the depth chart above gives the contour to line up on.

How much of Big Lake is shallower than 40 feet?

About half. The 40 ft contour encloses 34 acres of the roughly 125 acres inside the outer 5 ft line, so the other half of the water is shallower than 40 feet. The sharpest drop is between 20 and 30 feet, where the mapped water sheds 41 acres.

How accurate is this Big Lake depth map?

The contours come from the Michigan DNR Inland Lake Contours survey, retrieved August 2026 and last rebuilt on August 19, 2026. Depths change over time with water levels and sediment, so treat this map as a planning guide for fishing, and never use it for navigation. Acreages are computed from the published contour geometry, not from a separate area survey, so read them as close approximations.

Michigan lake depth maps

Big Lake depth map

Big Lake in Otsego County, Michigan reaches a depth of 81 feet. Big Lake is charted here across 9 closed depth contours, from the 5 ft line down to 80 ft, enclosing about 125 acres of water. Half of that water lies inside the 40 ft line, and only under an acre lie inside the deepest one. Every contour is on the interactive map below, free and without an account.

Data: Michigan DNR Inland Lake Contours (public record). Contours closed, checked and area-computed by Jordan Carter, founder of GilledIt · page updated August 19, 2026

Big Lake depth chart: 9 depth contours from 5 to 80 ft

Data: Michigan DNR Inland Lake Contours (public record), retrieved August 2026 · depths change over time · not for navigation

Big Lake depth chart data: water enclosed by each contour
Depth contour	Water inside it	Share of mapped water
5 ft	125 acres	100%
10 ft	115 acres	92%
20 ft	108 acres	86%
30 ft	67 acres	54%
40 ft	34 acres	27%
50 ft	20 acres	16%
60 ft	12 acres	9.9%
70 ft	5.3 acres	4.2%
80 ft	under 1 acre	under 1%

Acreages are computed from the closed Michigan DNR Inland Lake Contours contour rings, with islands subtracted. Shares are of the 125 acres inside the outermost charted contour (the 5 ft line), which is the outer edge of the mapped water, several state files carry no 0 ft shoreline line, so this is not the same as a share of the lake's published surface area. The survey also records a 81 ft sounding, marked as a point rather than a closed contour, so it is not charted as a band.

Fishing Big Lake: a stepped drop into deep water

The survey encloses about 125 acres of Big Lake inside its 5 ft contour, and half of that water lies inside the 40 ft line, so the drop to the deep basin comes in stages, each contour giving up another slice of water, rather than in one abrupt wall. Between 20 and 30 ft the mapped water sheds 41 acres in 10 ft of depth, the sharpest change on the chart, start on that band, because it is where the bottom stops being flat. Inside the 80 ft contour there is under an acre of water, toward the northwestern corner of the lake: a single pocket rather than a basin, and worth a drift over in high summer. 81 ft of water makes this a two-story fishery: warm-water fish hold the 5-to-40 ft ground while the basin can stay cold below the summer thermocline, and the traffic between the two runs along the 20–30 ft break at first and last light.

Ice fishing on Big Lake

Big Lake freezes later and less evenly than the shallow waters around it, and the winter bite sets up on the first real break rather than out over the 80 ft hole. The 20–30 ft band on the chart above is that edge: 41 acres of bottom tilt away there, and panfish and walleye slide up and down it through the day. Late ice pushes fish back onto the 5-to-40 ft flat. Check ice thickness locally before you walk out.

Big Lake depth map FAQs

How deep is Big Lake?: Big Lake reaches a maximum depth of 81 feet in the Michigan DNR Inland Lake Contours survey. Most of it is far shallower: the survey charts 9 closed depth contours over about 125 acres, and half of that water sits inside the 40 ft line. The 81 ft figure is a single recorded sounding rather than a closed contour, so the deepest line you can actually trace on the map is 80 ft.
Where is the deepest part of Big Lake?: The deepest charted water on Big Lake lies inside the 80 ft contour, toward the northwestern corner of the lake. That contour encloses under an acre, under 1% of the mapped water, so it is a small target on a small water, the depth chart above gives the contour to line up on.
How much of Big Lake is shallower than 40 feet?: About half. The 40 ft contour encloses 34 acres of the roughly 125 acres inside the outer 5 ft line, so the other half of the water is shallower than 40 feet. The sharpest drop is between 20 and 30 feet, where the mapped water sheds 41 acres.
How accurate is this Big Lake depth map?: The contours come from the Michigan DNR Inland Lake Contours survey, retrieved August 2026 and last rebuilt on August 19, 2026. Depths change over time with water levels and sediment, so treat this map as a planning guide for fishing, and never use it for navigation. Acreages are computed from the published contour geometry, not from a separate area survey, so read them as close approximations.

Depth maps for lakes near Big Lake

Big Chub Lake depth map · 74+ ft max · 8 mi away
Bridge Lake depth map · 87 ft max · 8 mi away
Heart Lake depth map · 123 ft max · 10 mi away
Big Bradford Lake depth map · 102 ft max · 12 mi away
Seventh Spectacle Lake depth map · 32 ft max · 12 mi away

Mapped fishing venues near Big Lake

Big Lake in the venue directory covers access and fishing details for this water.

Big Chub Lake · 8 mi away
Bridge Lake · 8 mi away
Heart Lake · 10 mi away

Fishing in Michigan needs a state license: Michigan fishing license guide · all Michigan venues