- [Narrator] For over 50 years, Lake Erie has experienced an increase in severe algae blooms due to agricultural runoff and other factors.

An algae bloom is an increase in cyanobacteria concentrations, otherwise known as blue-green algae, which can product toxic microcystin.

- Symptoms of the toxin from microcystin are vomiting, diarrhea, eye irritation, and rashes.

Those are the short-term symptoms, but the long-term symptoms can be cancers, liver and kidney issues, death.

Algal toxins have been around for literally billions of years, longer than there have been human beings.

- [Narrator] On February 26, 2019, voters in Toledo voted to amend the Toledo city charter and acknowledged that the Lake Erie ecosystem has legal rights to exist, flourish, and naturally evolve.

The vote was a reaction to a water crisis in August 2014 when toxic algal blooms caused a do-not-drink alert for 400,000 residents.

Before people settled in Northwest Ohio, it was a vast swampland known as the Great Black Swamp.

- It was about a 1,500 square mile area from Lake Erie all the way over to Fort Wayne, Indiana, so a really large wetland complex.

Around the 1800s, we cleared and drained the swamp to produce some of the best agricultural soils found anywhere in the world.

But in doing so, we kinda went a little outta balance and we went a little far.

- [Narrator] Traditionally, farmers used nitrogen and phosphorous to fertilize crops in an effort to replenish nutrients absorbed by the previous crops.

High phosphorous levels caused by runoff into ditches, rivers, and eventually into Lake Erie, have contributed to the thriving toxic algae blooms.

- In our shallow part of Lake Erie, it is only 20, 30 feet deep.

So it's warm, full of organic matter, but when we add phosphorous to it and nitrogen from excess either manure or fertilizer or other processes, it will create a bumper crop of cyanobacteria.

- [Narrator] Cyanobacteria, a blue-green algae that can produce toxic microcystin, can be found all over the United States.

According to the US Geological Survey, blooms have been implicated in both human and animal illness and death in at least 43 states.

In August of 2016 alone, at least 19 states had public health advisories because of cyanobacteria.

- This isn't an old problem that farmers have been burying their heads in the sand about.

This is a new revelation to folks and a new problem that we need to deal with in terms of what are the repercussions and potentially even what are the good conservation practices of the past maybe having negative repercussions here?

The farming community, we drink that water also.

Most of these farmers are passing these acres down generation to generation, so if we're watching major significant nutrients flow off our fields, it's not good for us either.

- [Narrator] To prevent further damage to the lake, many solutions have been proposed.

Our understanding of algae blooms and what causes them has changed.

- [Yvonne] Originally, the biggest concern was the phosphorous that was attached to the sediment, so we were really trying to keep the soil from coming off of the fields.

We were very concerned with what was on top.

Now the phosphorous that we're looking at is dissolved reactive phosphorous.

So now we're concerned more about what's happening down deeper and what's happening in the subsurface.

- [Narrator] Farmers and conservationists together are looking to the past for answers and possible solutions for the excess phosphorous runoff into Lake Erie.

One such solution is currently being tested on a farm in Ohio by reinstating a wetland to act as a natural filtration system between a farm and a runoff ditch.

- There's 32 species of trees and shrubs in this wetland planting, but we based it off of some sites that are known to be good quality remnants of the historic Great Black Swamp.

So the water that's coming off of the farm is actually running into the wetland, where the nutrients are being uptaken by all the trees and shrubs that we planted rather than flowing into the ditch and eventually Lake Erie.

So anything we can do to intercept those nutrients before they get into the lake is gonna help improve water quality.

- [Narrator] Although wetland restoration is one attempt to prevent algae blooms, the Lake Erie Bill of Rights could potentially hold people and organizations accountable for their actions.

It has been challenged every step of the way.

Proponents of the Lake Erie Bill of Rights say that citizens are taking stewardship into their own hands.

(gentle music)