How do I use this map?

Click on a location icon to see recent conditions. Blue Water Baltimore follows guidance from the Code of Maryland Regulations (COMAR) to determine if a site is meeting state-mandated water quality standards at any given time. For parameters without an established COMAR water quality standard, thresholds are derived from the Mid-Atlantic Tributary Assessment Coalition (MTAC) Eco-Check protocols for tidal and nontidal waterways at the point where “good” water health degrades into “fair” health.

• Pass: The selected parameter achieves the relevant COMAR/MTAC assessment threshold value (yay!).

• Fail:  The selected parameter does not achieve the relevant COMAR/MTAC assessment threshold value (boo).

• Grey:  The selected parameter does not have an associated COMAR water quality standard, or the parameter does not pertain to this site.

DISCLAIMER: Conditions can change at any time, including the time between water sample collection and when the data (such as bacteria levels) are analyzed and shared via this map. Current year data are provisional and have not yet been through our rigorous Quality Assurance (QA) procedures. Historic data can be downloaded and terms of service can be found here. Certified data from the year prior will be added to the downloadable dataset and made available every spring.

The map you see here reflects thousands of hours of hard work and dedication by staff and volunteers, and we couldn’t have done it without the generous support of our funders and donor members like you.  Please consider donating to help us keep a pulse on the Baltimore Harbor and its tributaries.