Balancing the Ecological Scales

algae in Geist lake

Vegetation in Geist Reservoir is out of control. While Citizens Water will typically treat the lake with an algicide to avoid foul taste and smell in our water supply, they don’t treat the invasive Eurasian milfoil that has gained a foothold in the reservoir. Just like any other invasive species, the aquatic weed plagues the native plant and animal life and contributes to the degradation of an entire ecosystem.

Eurasian milfoil continues to grow and form thick mats over the surface of the water. This canopy of vegetation completely blocks out the sunlight and kills the native aquatic plants that fish and other underwater species rely on for food and shelter.

This aquatic weed threatens to overtake the lake and severely shift the ecological balance, making recreational activities like fishing and boating next to impossible.

Treatment Options

You’re probably wondering how we can control excessive and invasive weed growth. While many peoples’ minds will jump to using chemicals like aquatic herbicides or algicides to control the weeds, there are first some questions worth addressing:

  • Do you know whether the use of chemicals in this body of water will be safe for you and the environment?
  • Are you using approved chemicals?
  • Have you obtained a permit?

If you are unsure about the safety and impact of a particular product, you should visit to learn more.

Although the weeds may be invasive and annoying, there’s still a need to maintain these native plants. As the base of the aquatic food chain, they provide habitat, shelter, and oxygen for fish and other organisms. Native plants also stabilize the sediments that would otherwise be erodible and provide nutrient competition for the blue-green algae

If you insist on removing the milfoil manually, pull it up by the roots and keep the plant intact as you dispose of it. Just like weeding dandelions in your yard, the idea is to avoid breaking off pieces that can float off and reseed elsewhere.

Excessive weed control and improper use of herbicides can destroy valuable habitats by releasing nutrients into the water, which in turn can stimulate the growth of algal blooms (rapid accumulation of microscopic algae). These algal blooms will cause water to turn an unsightly green color. Once they die off or “crash,” they can deplete the water of oxygen and cause a subsequent fish kill. Worse yet is when algal blooms can become toxic, posing a threat to our health.

Annual Geist Aquatic Weed & Algae Control Program

The Geist Lake Coalition (GLC) helps control the invasive species with our annual aquatic weed and algae control program. We use top-quality, EPA-approved herbicides and algaecides to manage resident lake access areas.

Our focus is in lockstep with the Indiana Department of Natural Resources, Indiana Department of Environmental Management, and Citizens Water.

Maintain a balance between recreation, protection of property values and aesthetics, and protection of a healthy fish population for the sport/hobby of fishing.

While the GLC doesn’t have the means to manage the invasive species throughout the entire lake, we offer annual water management for a contribution from property owners, dock owners, and community associations.

Our sliding contribution scale was designed so that funds could be distributed as fairly as possible based on relative distance from the lake. For example:

  • Lakefront homeowners: $1,100 per property
  • Non-Lakefront homeowners with deeded docks: $500.00 per property
  • Non-Lakefront homeowners with no deeded docks: $100.00 per property

Contributions from homeowners that are not lakefront without a deeded dock will be used to treat common areas and hot spots as they occur throughout the season.