Measuring and Mapping Water Health and Pollution in the Patapsco and its Tributaries

A project of Blue Water Baltimore

Water Watch

Measuring and mapping the health of Baltimore’s waterways


Our Impact

Blue Water Baltimore, home of the Baltimore Harbor Waterkeeper, routinely monitors water quality at 49 stations in the rivers, streams and harbor of the Patapsco River watershed. Using our data we calculate scores for the health of Baltimore’s waters according to Mid-Atlantic Tributary Assessment Coalition (MTAC) protocol.



Monitoring Sites


Readings Collected


Years of Watershed Health

Parameters Monitored



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Water Clarity

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Dissolved Oxygen

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Fecal Bacteria

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Our Monitoring Program

Each year, Blue Water Baltimore collects and synthesizes tens of thousands of individual data points in order to score the health of 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.  

Rapid Bacteria Testing

In April 2019, Blue Water Baltimore began using new rapid bacteria testing methods on water samples from several sites in the Baltimore Harbor that are commonly used for boating, fishing, and other recreational activities. We analyze these samples in-house at our own water quality lab, which allows us to return results to the public faster than ever before. See our Current Conditions map for the most recent readings.

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Why This Matters

Blue Water Baltimore is home to the Baltimore Harbor Waterkeeper and a proud member of the international Waterkeeper Alliance. 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. Our Waterkeeper and staff scientists who lead our ambient water quality monitoring that generates the data for this report are supported by private and governmental grants as well as donations from supporting members.

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