Chesapeake Bay Coastal Bays Rivers and Streams Watersheds
Maryland Department of Natural Resources
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Lower Potomac River - Indian Head (TF2.3)

Map Showing the Location of TF2.3

Indian Head Point on the Potomac River, Near Marbury and Potomac Heights

Coordinates (NAD83):
Latitude: 38.6082
Longitude: -77.1739

This station is a tidally influenced fresh water site in the mid-channel of the Potomac River, with an approximate depth of 45 feet.

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 2012. 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.

2013 Surface Water pH
Lower Potomac River / Indian Head (TF2.3)


Range 1985 to 2012 2013 Mean

Surface Water pH
Lower Potomac River / Indian Head (TF2.3)
Month Minimum Mean Maximum 2012 2013
January 7.60 7.85 8.20 8.10 7.90
February 7.50 7.86 8.40 7.80 8.00
March 7.50 7.84 8.30 8.30 7.90
April 7.52 7.78 8.40 8.40 8.00
May 7.05 7.72 8.39 7.80 7.70
June 6.75 7.59 8.65 7.50 7.50
July 7.30 7.78 8.99 7.30 7.80
August 7.10 7.71 8.70 7.70 8.00
September 7.16 7.64 8.80 7.80 7.70
October 7.19 7.70 8.25 7.70 7.70
November 6.10 7.37 8.30 7.80 7.90
December 7.00 7.74 8.10 8.00 7.90

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

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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

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