Chesapeake Bay Coastal Bays Rivers and Streams Watersheds
Maryland Department of Natural Resources
Fixed Station Monthly Monitoring
More Info:
Monthly Monitoring Data
Eyes on the Bay
Continuous Monitoring
Water Quality Mapping

Chesapeake Bay Mainstem - Bay Bridge (CB3.3C)

Map Showing the Location of CB3.3C

North of the Chesapeake Bay Bridge

Coordinates (NAD83):
Latitude: 38.9951
Longitude: -76.3597

This station is a mid-channel site located in the upper Chesapeake Bay, just north of the Bay Bridge. This station is located in the turbidity maximum, where salt water from the ocean and freshwater from the upper Bay mix. The station is in the mesohaline zone (salinity 5 to 18 ppt); however, the station has quite a range in salinity. The approximate depth is 21 meters.

Current Parameter: pH

Choose Other Parameters:
Salinity pH Water

The yellow shaded area represents the range of monthly mean values that have occurred from 1985 to 2014. The blue line shows the monthly mean values for each month over that same time period. The red line shows what the current years conditions are and how they compare to the range and the average values we've seen.

*Note that the Mean pH is now correctly calculated by converting pH values to the representative H+ ion concentrations, averaging those concentrations, and converting back to pH scale. Prior to 2012, we were displaying averages of pH readings, which was statistically incorrect since pH readings are on a logarithmic scale.

2015 Surface Water pH
Chesapeake Bay Mainstem / Bay Bridge (CB3.3C)


Range 1985 to 2014 2015 Mean

Surface Water pH
Chesapeake Bay Mainstem / Bay Bridge (CB3.3C)
Month Minimum Mean Maximum 2014 2015
January 7.40 7.87 8.60 Not Sampled 7.80
February 7.60 7.97 8.50 8.20 8.00
March 7.35 7.93 8.60 8.40 8.40
April 7.44 7.87 8.60 7.80 8.40
May 7.47 8.08 8.90 9.10 8.20
June 7.50 8.01 9.00 8.25 8.00
July 7.90 8.23 8.80 8.10 8.65
August 7.86 8.25 8.79 8.45  
September 7.59 7.97 8.80 8.10  
October 7.58 7.88 8.30 8.10  
November 6.81 7.78 8.30 8.00  
December 7.50 7.91 8.40 8.20  

NOTE: Results displayed are provisional and have not undergone full Quality Assurance procedures. Although Maryland DNR believes the data presented here are correct, we cannot guarantee their accuracy at this time.

Choose Other Parameters:
Salinity pH Water

Return to the MapReturn to the Station Map

Additional water quality data, including nutrient data, is currently available through the Chesapeake Bay Program Data Hub.

Contact MD DNR's Resource Assessment Service at (410) 260-8630
or by email at

Chesapeake Bay | Coastal Bays | Rivers & Streams | Watersheds

Return to the Maryland DNR Home Page.

Your opinion counts! Take a survey!