On August 2, 2014, the City of Toledo issued a do-not-drink advisory for its entire water system. Microcystin — a liver toxin produced by harmful algal blooms in Lake Erie — had been detected in finished drinking water at levels exceeding the safe threshold. For three days, roughly 500,000 people in the Toledo metro area couldn’t drink, cook with, or bathe in their tap water.
It was a watershed moment, no pun intended, for Great Lakes water quality. And while Toledo has invested heavily in treatment upgrades since then, the conditions that caused the crisis — agricultural runoff, warming lake temperatures, and aging infrastructure — are still very much present.
What Happened in 2014
Toledo draws its drinking water from Lake Erie through an intake pipe in Maumee Bay. In the summer of 2014, a particularly severe harmful algal bloom (HAB) developed in the western basin of Lake Erie, driven by warm temperatures and heavy phosphorus loading from agricultural runoff.
The Collins Park Water Treatment Plant, which serves the Toledo area, detected microcystin in treated water at 1.12 micrograms per liter — above the World Health Organization’s guideline of 1 microgram per liter for safe drinking water. The plant’s treatment process, which had handled moderate algal blooms in previous years, couldn’t reduce microcystin levels enough to meet safety standards.
The do-not-drink order lasted until August 4, when treatment adjustments brought levels back down. But the damage to public trust was significant, and it triggered a fundamental rethinking of how Toledo manages its water supply.
The Phosphorus Problem
Lake Erie’s harmful algal blooms aren’t random events. They’re fueled primarily by dissolved reactive phosphorus from agricultural operations in the Maumee River watershed. The Maumee is the largest tributary feeding Lake Erie’s western basin, and it drains some of the most intensively farmed land in Ohio.
Key contributors include:
- Fertilizer application on cropland — particularly fall-applied manure and commercial fertilizer
- Tile drainage systems that fast-track dissolved phosphorus from fields into streams
- Concentrated animal feeding operations (CAFOs) in the watershed
- Urban stormwater runoff from Toledo and surrounding communities
Ohio, Michigan, and Ontario committed in 2015 to reducing phosphorus loading to Lake Erie by 40% by 2025. As of 2024, that target had not been met. The Maumee River continues to deliver massive phosphorus loads to the lake, particularly after heavy spring rains.
Post-Crisis Investments
Toledo has spent over $500 million upgrading its water treatment capacity since 2014. The Collins Park plant now uses:
- Granular activated carbon filters to remove microcystin and other organic compounds
- Advanced oxidation processes including ozone and UV treatment
- Real-time monitoring of source water and treated water for cyanotoxins
- Powdered activated carbon that can be added upstream in the treatment process when algal blooms intensify
These upgrades have been effective. Toledo has not issued another do-not-drink advisory since 2014, even during severe bloom years like 2015 and 2017. But the system is being tested every summer, and treatment costs continue to rise as blooms persist.
Lead Service Lines
Like many older Midwestern cities, Toledo has a significant number of lead service lines connecting water mains to homes. The city estimates there are approximately 26,000 lead service lines still in use across the system.
Toledo began an accelerated replacement program following the EPA’s revised Lead and Copper Rule. The city prioritizes replacements in neighborhoods where children’s blood lead levels are elevated and in schools and daycares.
Key lead-related data points:
- Toledo’s 90th percentile lead level has generally been below the EPA action level of 15 parts per billion
- However, individual homes with lead service lines can see much higher levels, particularly after periods of stagnant water
- The city uses corrosion control treatment (phosphate-based) to reduce lead leaching from pipes
Ongoing Water Quality Concerns
Beyond algal blooms and lead, Toledo’s water system faces several other challenges:
Disinfection byproducts (DBPs): The organic material in Lake Erie’s water reacts with chlorine during treatment to produce trihalomethanes (THMs) and haloacetic acids (HAAs). Toledo has periodically exceeded EPA limits for THMs, particularly during warm months when organic loading is highest.
Emerging contaminants: PFAS have been detected in Lake Erie and in Toledo’s treated water, though at levels below current EPA advisory limits. A 2023 USGS study found PFAS in all Great Lakes, with Erie’s western basin showing detectable levels of PFOA and PFOS.
Infrastructure age: Much of Toledo’s distribution system dates to the early-to-mid 20th century. The city faces hundreds of water main breaks annually, which can temporarily affect water quality in affected neighborhoods.
Lake Erie’s Broader Water Quality Picture
Toledo isn’t the only city affected by Lake Erie’s water quality issues. Communities across the western basin — including Oregon, Perrysburg, and parts of Michigan’s Monroe County — all draw from waters susceptible to HABs.
The state of Ohio has implemented several programs to address the phosphorus problem:
- H2Ohio initiative funds wetland construction, cover crop adoption, and nutrient management plans for farmers in the Maumee watershed
- Ohio EPA’s Harmful Algal Bloom Response Strategy coordinates monitoring and public notification during bloom season (typically June–October)
- The Great Lakes Restoration Initiative (federal) has funded research and remediation projects targeting Lake Erie specifically
Progress is real but slow. Some years show improvement in bloom severity; others, like 2015, produced blooms worse than 2014. Climate change is expected to increase the frequency and intensity of HABs by delivering more intense rainfall events that flush phosphorus into waterways.
What Toledo Residents Should Know
If you’re on Toledo’s municipal water system, the upgraded treatment plant provides strong protection against microcystin and other contaminants. The city publishes annual water quality reports and provides real-time algal bloom monitoring data during summer months.
That said, there are steps worth taking:
- Check your service line. Contact the Toledo Division of Water Distribution to find out if your home has a lead service line. If it does, consider a point-of-use filter certified for lead removal (NSF/ANSI 53).
- Flush before drinking after periods of non-use. Run cold water for 30 seconds to 2 minutes if the tap hasn’t been used for several hours. This clears water that’s been sitting in contact with pipes.
- Monitor bloom season. Ohio EPA posts weekly HAB advisories during summer. While the treatment plant handles microcystin effectively now, awareness helps if you’re drawing water from the lake for recreation or have a private intake.
- Consider whole-house or point-of-use filtration. Activated carbon filters address THMs, PFAS, and lead. Reverse osmosis systems provide the most comprehensive protection.
If you’re concerned about your water quality, a certified water treatment professional can test your water and recommend the right system for your situation. Given Toledo’s complex mix of source water challenges and aging infrastructure, knowing what’s in your water is the first step.
Related Reading
- Cleveland Water Quality: Lead Pipes and Lake Erie
- Akron OH Water Quality: Rubber Industry Legacy
- Columbus Ohio Water Quality: Lead and Algae
- Detroit Water Infrastructure and Lead Shutoffs
Sources
- City of Toledo 2014 Do-Not-Drink Advisory and response documentation
- Ohio EPA Harmful Algal Bloom monitoring data (2014–2025)
- USGS Great Lakes PFAS Study (2023)
- Toledo Division of Water Distribution lead service line inventory
- Ohio H2Ohio Initiative progress reports
- EPA Lead and Copper Rule compliance data for Toledo