water Connects Us All.

Blue Water Baltimore fights to make sure your waterways are clean and your neighborhoods are healthy.

Make Your Voice Heard

Baltimore’s Water Issues

Over one million people live in Baltimore’s watershed.

Baltimore’s waterways suffer from pollution caused by generations of industrial pollution, leaks from aging separate sewer and stormwater infrastructure, extensive hardscape, and widespread littering.

Our actions on land throughout the watershed directly impact water quality in the rivers that feed the Baltimore Harbor and the Chesapeake Bay. Blue Water Baltimore is actively working with residents and local authorities to prevent and remedy four major sources of water pollution:

Baltimore Water Quality FAQ

BWB doesn’t make specific recommendations about whether the Harbor is safe for swimming on any given day.

Our role is to help people understand both the risks inherent in recreating in urban waterways and the potential sources of pollution that are negatively impacting our streams and rivers. Our work centers on enforcing the Clean Water Act on behalf of our watershed communities, holding polluters accountable, and advocating for the upstream solutions that will result in fishable, swimmable waterways.

The decision whether or not to swim or recreate in our region’s waterways is a personal decision about what is an acceptable level of risk. We want to provide people with the information they need to make the best decisions that make sense for themselves and their families.

The Maryland Department of the Environment advises against swimming near a storm drain within 48 hours of a rain event. This is true anywhere in Maryland, but particularly in urban areas like Baltimore City, where everything is near a storm drain. While Baltimore’s sewers were designed to keep sewage and stormwater seperate, aging infrastructure and leaky pipes mean they often mix.

We regularly collect bacteria data throughout the Baltimore region’s streams, rivers and Harbor in both wet and dry weather to get a pulse on baseline water health, and what we’ve learned over 10+ years is that bacteria levels are often closely linked to rainfall, but not always.

Well, it’s not really that simple. There are illicit discharges and connections that cause sewage to flow into our Harbor, even in dry weather.  The last portion of Baltimore City’s quarterly Modified Consent Decree reports show a list of any illicit sewage discharges discovered over the previous 90 days. For example, in report #23 for the quarter ending June 2023, there were 70 reported overflows, totaling over 260,000 gallons spilled into our waterways.

Sewage contamination is so unpredictable that we can’t ever be 100% certain that the Harbor is safe to recreate in; and at the same time, we strongly support the right of everyone to clean water, and opportunities for safe recreation in our urban waterways.

Our ambient water quality monitoring is available online at BaltimoreWaterWatch.org. The data shows that the Baltimore Harbor often doesn’t meet bacterial water quality standards, particularly when it rains. Click on any of monitoring stations and select bacteria trends to see a graph showing over 10 years of measurements.

Additional information about swimming safety in our regions waterways is available from state and local health departments online:

It could be anything really, and you should report any concerns to our pollution hotline, but there are a couple of common algae blooms that recur year after year in the Patapsco: mahogany tides (red/brown) and pistachio tides (light green). The pistachio tides look particularly concerning, but they do occur naturally, in that it’s not someone dumping green waste into the harbor. These blooms aren’t good signs for the underlying water quality, and you can read more at this blog post.

Additionally, sometimes the Baltimore Department of Public Works does use green “tracking dye” to locate leaks in pipes, which can appear similar to a pistachio tide, but is harmless.

Fixing Baltimore’s water issues

Blue Water Baltimore is your clean water watchdog

Blue Water Baltimore collects and synthesizes tens of thousands of individual data points every year in order to assess our regional waterways.

Every indicator we track is equally important; from the Dissolved Oxygen content in the Inner Harbor to the Conductivity levels in the Towson Run, each measurement has a story to tell about the ecology of our streams, rivers, and harbor – and the pollutants degrading them.  

The long-term dataset that Blue Water Baltimore has been building since 2013 is used by academic institutions, state regulators, local law-makers, and members of the public to make informed decisions about our waterways.  It’s also the scientific backbone of the restoration, advocacy, outreach, and education work we conduct year-round.  


monitoring sites


readings collected


years of watershed health data

How to fix Baltimore city water issues?

Restore the quality of Baltimore’s water

This pollution not only harms our environment, but it also threatens the health of our citizens and the vitality of our local economy.

But Blue Water Baltimore is fighting back.

To address these issues, Blue Water Baltimore is collaborating with residents, businesses, and property owners to reduce pollution and implement tangible solutions in order to ensure clean waterways and healthy neighborhoods.

We also advocate at the local, state and federal level to ensure that water pollution laws are enforced, that emerging pollution issues are addressed with new enforceable laws, and that clean water regulatory programs are funded and implemented effectively.

Clean water is a human right.

Blue Water Baltimore is our waterway’s first line of defense against pollution.

Here’s how to help

Join the fight to fix Baltimore’s water issues

Our mission is to restore the quality of Baltimore’s rivers, streams, and harbor to foster a healthy environment, a strong economy, and thriving communities.

Here are the best ways to get involved

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Stay Informed

Join our mailing list to get updated information on water qualities, on opportunities for making impact, and for special invitations to local events.

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Volunteer with us

Meet new people, explore Baltimore, and lend a helping hand as a Blue Water Baltimore volunteer to protect and improve our city!

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Become a member

A donation of any size makes you a member of Blue Water Baltimore and part of our fight for clean water and strong communities.