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Michigan lake depth maps

Long Lake depth map

Long Lake in Iron County, Michigan reaches a depth of 105 feet. Long Lake is charted here across 14 closed depth contours, from the 5 ft line down to 100 ft, enclosing about 61 acres of water. Half of that water lies inside the 35 ft line, and only 2 acres 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

Long Lake depth chart: 14 depth contours from 5 to 100 ft

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

Long Lake depth chart data: water enclosed by each contour
Depth contourWater inside itShare of mapped water
5 ft61 acres100%
10 ft53 acres87%
15 ft47 acres76%
20 ft43 acres70%
25 ft39 acres64%
30 ft34 acres56%
35 ft29 acres47%
40 ft24 acres39%
50 ft20 acres33%
60 ft16 acres26%
70 ft12 acres19%
80 ft7.1 acres12%
90 ft4.7 acres7.6%
100 ft2 acres3.2%

Acreages are computed from the closed Michigan DNR Inland Lake Contours contour rings, with islands subtracted. Shares are of the 61 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 105 ft sounding, marked as a point rather than a closed contour, so it is not charted as a band.

Fishing Long Lake: a stepped drop into deep water

Inside its outermost 5 ft contour the survey charts about 61 acres of Long Lake, with the 35 ft line enclosing half of it, so the bottom steps down contour by contour into the deep basin rather than shelving flat or plunging all at once. The sharpest change on the chart is between 5 and 10 ft, where the mapped water loses 8 acres in 5 ft of depth, that band is the contour to work first, because it is where the bottom stops being flat. 2 acres, 3.2% of the mapped water, lie inside the deepest 100 ft contour, toward the middle of the lake. At 105 ft this is two-story water: the basin can stay cold below the summer thermocline while warm-water fish stay up on the 5-to-35 ft ground, and the fish that move between the two do it along the 5–10 ft break at first and last light.

Ice fishing on Long Lake

Deep water like Long Lake freezes later and less evenly than the shallow lakes around it, and the winter bite sets up on the first real break, not out over the 100 ft hole. That edge is the 5–10 ft band on the chart above, where 8 acres of bottom tilt away, and panfish and walleye work up and down it through the day. By late ice the fish push back onto the 5-to-35 ft flat. Check ice thickness locally before you walk out.

Long Lake depth map FAQs

How deep is Long Lake?
Long Lake reaches a maximum depth of 105 feet in the Michigan DNR Inland Lake Contours survey. Most of it is far shallower: the survey charts 14 closed depth contours over about 61 acres, and half of that water sits inside the 35 ft line. The 105 ft figure is a single recorded sounding rather than a closed contour, so the deepest line you can actually trace on the map is 100 ft.
Where is the deepest part of Long Lake?
The deepest charted water on Long Lake lies inside the 100 ft contour, toward the middle of the lake. That contour encloses 2 acres, 3.2% 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 Long Lake is shallower than 35 feet?
About half. The 35 ft contour encloses 29 acres of the roughly 61 acres inside the outer 5 ft line, so the other half of the water is shallower than 35 feet. The sharpest drop is between 5 and 10 feet, where the mapped water sheds 8 acres.
How accurate is this Long 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 Long Lake

Mapped fishing venues near Long Lake

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

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