If you’ve had the privilege of experiencing Geist Reservoir for yourself, you know how amazing it is to live the lake life so close to Indianapolis. What’s more, is this fine reservoir stretches across 1900 acres and holds over 6 billion gallons of water.

Though many people know the reservoir as a place for summer relaxation and fun, this massive body of water has endured a lot over the years—and we wanted to share some of the reservoir’s fascinating history. Here’s a look at Geist Reservoirs’ past, present, and future.


Indiana residents have enjoyed Geist Reservoir ever since it was constructed by damming Fall Creek in 1943 to provide water for Indianapolis. Upon completion, Geist Reservoir became the second-largest human-made lake in Indiana, providing 7 billion gallons of water. Residents of Geist are most likely familiar with the shallow waters (10 feet or less) and the rapid development the area has seen over the years.

With that being said, several factors have aged Geist to appear much closer to 120 years old than its actual age. While Geist has always been a place for families to make memories, the 78-year-old reservoir needs swift ecological attention and homeowner support to survive into the next decade.


Today, Geist Reservoir covers 1,900 acres and spans three Indiana counties (Marion, Hamilton, and Hancock). While the reservoir has become well-known for luxurious living and family fun, in recent years, it has begun experiencing problems with algal blooms and invasive aquatic species.

With issues concerning blue-green algae, invasive Eurasian milfoil, and excessive silt, the reservoir is in dire need of our help. Without proper attention and maintenance, this body of water will inevitably become unsuitable for fishing, swimming, and boating—its three main attractions.  

Not to mention, improper care of this great reservoir will lead to the degradation of the entire ecosystem. When it looks like you could walk across the water on weeds and algae—it’s a sign that something needs to be done. This thick vegetation blocks the sunlight from reaching the bottom of the lake, killing the native aquatic plants that provide food and shelter for fish and other underwater species.

As such a tremendous asset to the area, the slow demise of Geist Reservoir is also projected to significantly impact home values, both on-water and off-water. Realtors in the area can attest to the draw of the lake to nearby areas:

“As realtors in this community, we see on a daily basis how the lake supports the community. We see how it draws people to this area. We see the joy it provides residents, the pride that people have to live in this community. While summer-long algae and weed treatment programs administered by the Geist Lake Coalition have made an immediate impact on the “curb appeal” of Geist Reservoir, there are deeper problems on the horizon that require long-term, sustainable funding solutions that can only be achieved through the establishment of a reservoir conservancy district. 

The reservoir conservancy district provides the best solution for protecting Geist Reservoir,” continue the local realtors. “Protecting Geist serves to protect this community and the property values of everyone who lives near the lake and enjoys all the lake has to offer. As realtors, we support the creation of the Geist Reservoir Conservancy District.”


While most reservoirs have a useful life of 50 to 100 years, most reservoirs also receive systemic maintenance throughout their lifetime. Not Geist. Unfortunately, Geist Reservoir was built in 1943—and since then, no one has taken on the responsibility of sustaining this great body of water. While Geist Lake Coalition has treated the lake using donations from those in the area, we can only do so much with the donated funds. 

Just like anything human-made, if you create a lake and then don’t take the proper steps to preserve it, eventually nature will take it back over. And that’s exactly what is happening at Geist Reservoir in the present and will continue happening into the future unless appropriate steps are taken to help Geist thrive.

One possible scenario we would like to avoid is a situation similar to Grand Lake in nearby St. Marys, Ohio. Grand Lake, a reservoir of similar age, experienced some of the very same warning signs Geist is experiencing today. With a history of untreated sedimentation and runoff issues, as well as several outbreaks of blue-green algae blooms, Grand Lake was officially declared toxic in 2010. 

But hope isn’t completely lost. Today—after over a decade and millions of dollars in conservation efforts later—Grand Lake’s conditions have finally started to improve. Conservation pays off, and Grand Lake is a great example of how Geist can be proactive rather than reactive in the quest to preserve our great reservoir.  

A Brighter Tomorrow

We’re here to fight for a brighter tomorrow. However, the fight can only continue if the Geist Reservoir community continues to follow a pattern of conscious efforts to improve the waters’ quality. The formation of a Reservoir Conservancy District would allow the community to do this with ease.

Want to help us secure a bright future for Geist? Learn more about how to help here.