How deep is Rainbow Reservoir?

Rainbow Reservoir reaches a maximum depth of 35 feet in the CT DEEP Lake Bathymetry survey. Most of it is far shallower: the survey charts 8 closed depth contours over about 242 acres, and half of that water sits inside the 10 ft line.

Where is the deepest part of Rainbow Reservoir?

The deepest charted water on Rainbow Reservoir lies inside the 35 ft contour, toward the northeastern 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 Rainbow Reservoir is shallower than 10 feet?

About half. The 10 ft contour encloses 90 acres of the roughly 242 acres inside the outer 0 ft line, so the other half of the water is shallower than 10 feet. The sharpest drop is between 0 and 5 feet, where the mapped water sheds 87 acres.

How accurate is this Rainbow Reservoir depth map?

The contours come from the CT DEEP Lake Bathymetry 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.

Connecticut lake depth maps

Rainbow Reservoir depth map

Rainbow Reservoir in Thompson, Connecticut reaches a depth of 35 feet. Rainbow Reservoir is charted here across 8 closed depth contours, from the 0 ft line down to 35 ft, enclosing about 242 acres of water. Half of that water lies inside the 10 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: CT DEEP Lake Bathymetry (CC0). Contours closed, checked and area-computed by Jordan Carter, founder of GilledIt · page updated August 19, 2026

Rainbow Reservoir depth chart: 8 depth contours from 0 to 35 ft

Data: CT DEEP Lake Bathymetry (CC0), retrieved August 2026 · depths change over time · not for navigation

Rainbow Reservoir depth chart data: water enclosed by each contour
Depth contour	Water inside it	Share of mapped water
0 ft	242 acres	100%
5 ft	155 acres	64%
10 ft	90 acres	37%
15 ft	60 acres	25%
20 ft	42 acres	17%
25 ft	24 acres	9.9%
30 ft	6.2 acres	2.6%
35 ft	under 1 acre	under 1%

Acreages are computed from the closed CT DEEP Lake Bathymetry contour rings, with islands subtracted. Shares are of the 242 acres inside the outermost charted contour (the 0 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.

Fishing Rainbow Reservoir: a broad shallow flat

About 242 acres of Rainbow Reservoir sit inside the survey's 0 ft contour, and half of that water is already gone by the 10 ft line: the bulk of this Thompson water sits on a shallow flat, with the real depth packed into one part of the basin. The steepest break on the chart runs from 0 down to 5 ft: 87 acres of bottom fall away across 5 ft there, which makes that band the first contour to work. Inside the 35 ft contour there is under an acre of water, toward the northeastern corner of the lake: a single pocket rather than a basin, and worth a drift over in high summer. Nothing here reaches a true cold-water layer at 35 ft, so structure does the thermocline's work: the points and inside turns where the 0 and 5 ft lines pinch together fish hardest in early season, and again as fish follow bait back down in autumn.

Ice fishing on Rainbow Reservoir

At 35 ft, Rainbow Reservoir is a workable ice depth: deep enough to hold fish all winter without the slow freeze-up of a big basin. Start on the 35 ft hole, 0.1 acres of it, at first light, then move up onto the 0–5 ft break as the sun gets up, and fish the flats inside the 10 ft line through the middle of the day. Check ice thickness locally before you walk out.

Rainbow Reservoir depth map FAQs

How deep is Rainbow Reservoir?: Rainbow Reservoir reaches a maximum depth of 35 feet in the CT DEEP Lake Bathymetry survey. Most of it is far shallower: the survey charts 8 closed depth contours over about 242 acres, and half of that water sits inside the 10 ft line.
Where is the deepest part of Rainbow Reservoir?: The deepest charted water on Rainbow Reservoir lies inside the 35 ft contour, toward the northeastern 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 Rainbow Reservoir is shallower than 10 feet?: About half. The 10 ft contour encloses 90 acres of the roughly 242 acres inside the outer 0 ft line, so the other half of the water is shallower than 10 feet. The sharpest drop is between 0 and 5 feet, where the mapped water sheds 87 acres.
How accurate is this Rainbow Reservoir depth map?: The contours come from the CT DEEP Lake Bathymetry 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 Rainbow Reservoir

Twin Lakes South depth map · 18 ft max · 8 mi away
Congamond Lakes depth map · 40 ft max · 9 mi away
McDonough Lake depth map · 50 ft max · 13 mi away
Wethersfield Cove depth map · 15 ft max · 13 mi away
Keeney Cove depth map · 24 ft max · 13 mi away

Mapped fishing venues near Rainbow Reservoir

Rainbow Reservoir in the venue directory covers access and fishing details for this water.

McLean Game Refuge · 7 mi away
Twin Lakes South · 8 mi away
Congamond Lakes · 9 mi away

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