Chesapeake Bay Coastal Bays Rivers and Streams Watersheds
Maryland Department of Natural Resources
Fixed Station Monthly Monitoring
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Middle Potomac River - Little Falls (POT1184)CORE/Potomac - (POT1184)

Map Showing the Location of POT1184

Little Falls on the Potomac River, Just North of Washington, D.C.

Coordinates (NAD83):
Latitude: 38.9482
Longitude: -77.1272
Latitude: 38.9482
Longitude: -77.1273

This station is a shallow, non-tidal, fresh water site where water clarity and salinity are not measured.PO09;Potomac River Gage station above Little Falls Dam; Characterizes free-flowing freshwater

Current Parameter: pH

Choose Other Parameters:
Salinity pH Water

The yellow shaded area represents the range of monthly mean values that have occurred from 1986 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
Middle Potomac River / Little Falls (POT1184) CORE/Potomac / (POT1184)


Range 1986 to 2014 2015 Mean

Surface Water pH
Middle Potomac River / Little Falls (POT1184)CORE/Potomac / (POT1184)
Month Minimum Mean Maximum 2014 2015
January 6.80 7.78 8.70 7.90 7.10
February 6.60 7.60 9.30 7.90 8.10
March 6.90 7.74 9.30 7.80 Not Sampled
April 6.30 7.53 8.90 7.90 7.60
May 7.50 7.94 8.90 7.90 8.10
June 7.30 7.93 9.00 8.10 8.40
July 7.20 7.98 8.80 8.20 7.80
August 7.00 7.83 8.90 7.60  
September 7.10 7.99 8.70 8.10  
October 7.20 7.90 8.60 8.20  
November 7.20 8.03 9.00 8.40  
December 6.70 7.69 8.60 8.00  

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

Chesapeake Bay | Coastal Bays | Rivers & Streams | Watersheds

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