Field Notes

May 13, 2020

Ponds vs. lakes… what’s the difference?

Read Time: 3 minutes

Ponds and lakes are both inland bodies of freshwater that contain living creatures. At first glance, they seem very similar!

To help determine the difference, both the depth and surface area must be considered. Lakes are normally much deeper than ponds and have a larger surface area. All the water in a pond is in the photic zone, meaning ponds are shallow enough to allow sunlight to reach the bottom. This causes plants (sometimes too many) to grow at the bottom of ponds as well as on their surface. However, sunlight can’t reach the bottom of all areas of lakes. Lakes have aphotic zones, which are deep areas of water that receive no sunlight, preventing plants from growing.

In general, ponds have smaller waves than lakes. Waves smaller than 12 inches in height would generally be considered small. Water throughout ponds also tends to be more uniform in temperature, unlike water in lakes which can have a variety of water temperature depending on the depth.

How to take care of a pond

If you have a pond on your property, you might be wondering how to care for it in a way that makes it useable: how to remove or limit aquatic vegetation, stock fish, or test the health of the water. Let’s look at each of these important topics.

Don’t have a pond, but want to install one? Start here.

Remove or limit aquatic vegetation

Perhaps the most frustrating part of owning or living close to a pond is the amount of weeds and algae it seems to produce. One reason ponds are prime plant producers is how shallow they are. Sunlight can reach all the way to the bottom, giving plants the energy they need to grow.

In the right amounts, weeds and algae are healthy for ponds. They provide habitats and food for critters that live on the land and in the water. When they’re out of control, though, weeds and algae limit your ability to enjoy all the pond can offer. Here are a few steps you can take to reach a healthy balance:

  • Before you start pulling up plants, talk to the experts! Aquatic weed specialists will be able to tell you what you should and shouldn’t get rid of. Reach out to Aquatic Weed Control or Aquatic Control.
  • Identify what’s growing. Even before you call in a specialist to get rid of the weeds, identify what’s growing. This PDF from Purdue can help you get started.
  • Lawn fertilizer run-off is another reason weeds and algae might be growing in your pond. Fertilizer helps your garden grow; it also helps unwanted weeds and algae grow. Try switching to an organic fertilizer or starting a compost pile.

Stock fish in a pond

If you’re considering stocking a pond, make sure it can support a healthy fish habitat. Fish need dissolved oxygen (DO) to survive; aquatic plants are a key source of fresh DO. Fish also need a structure to live in.

Structure provides surface area for organisms like macroinvertebrates and algae to grow on, in addition to providing cover for fish. Structure also provides places for fish to hide, eat, or spawn.


There are several Indiana-native fish species that you can add to your pond: bluegill, bass, catfish and sunfish. You should add the right number of fish based on the size of the pond, and only purchase the fish from reliable suppliers. This document from Purdue will help you get started!

Test the health of the water

A water test can help you understand the water quality of your pond, and if it has an imbalance of certain substances, like phosphorus, which can lead to excess weeds and algae. You could also learn about dissolved oxygen content, nitrate, nitrite, pH, and the total depth of the pond.

The Lilly Center would be happy to be a resource for you as you get to know and care for your pond! Water testing isn’t always necessary to determine next-steps for your pond’s health. Contact us with a description of your pond and the problem you’re noticing, and we’ll follow up with questions and best-practice suggestions.

Some ponds and lakes are easy to identify while others are harder to determine. In fact, there is no precise, scientific difference between the two. What may be considered a lake in one area may be considered a pond in another.

What we know for sure is that both lakes and ponds are home to many living creatures, and enjoyed recreationally by families and individuals. Living creatures in both ponds and lakes rely on healthy water in order to survive and thrive. You can help protect all the waterways of Kosciusko County from your own property! Aside from the best-practices mentioned above, here are few ways to get started.

How to identify Blue-green algae

What to read next: How to identify blue-green algae

Blue-green algae can bloom in any body of water, but especially ones that are shallow, warm and get too many nutrients. Why does that matter? Because blue-green algae can produce a toxin that’s harmful to both people and pets.

When in doubt, stay out