How to Calculate the Depth of a Lake

Determine Lake Depth with a Sonar

• 1

  Mount a fish finder sonar on a boat.

• 2

  Launch the boat.

• 3

  Turn on the sonar.

• 4

  Move the boat across the lake while watching the depth number. Note where the deepest points are along the way.

• 5

  Spiral in around the deepest points to find which is the deepest.

Determine Lake Depth with a Rope and Weight

• 6

  Tie the rope to the weight.

• 7

  Bring the boat to the middle of the lake.

• 8

  Lower the weight into the water slowly. When it touches the bottom, mark the rope and pull the weight back.

• 9

  Lower the weight in several nearby locations. If the deepest mark is under water, mark the new deepest point. Continue until satisfied with the accuracy of the depth point.

• 10

  Move to land and measure the rope with a tape measure.

Find Lake Depth Information on the World Lake Database

• 11

  Launch a web browser.

• 12

  Search the World Lake Database for the lake whose depth you are measuring.

• 13

  Write down the deepest point and the mean lake depth.