Conversion Factors and Datums

Conversion Factors

Inch/Pound to SI

Multiply	By	To obtain
Length
inch (in.)	25.40	millimeter (mm)
foot (ft)	0.3048	meter (m)
mile (mi)	1.609	kilometer (km)
Area
square mile (mi2)	2.59	square kilometer (km2)
Volume
gallon (gal)	3.785	liter (L)
cubic foot (ft3)	0.02832	cubic meter (m3)
Flow rate
cubic foot per second (ft3/s)	0.02832	cubic meter per second (m3/s)

Chemical concentrations, volumes of water, and mass of rocks collected for analyses are reported in SI units:

SI to Inch/Pound

Multiply	By	To obtain
Excess air concentration
cubic centimeter per liter (cm3/L)	0.2310	cubic inch per U.S. gallon (in3/gal)
Chemical concentration
milligram per kilogram (mg/kg)	0.0070	grain per pound (gr/lb)
milligram per liter (mg/L)	0.05841	grain, avoirdupois per gallon (gr/gal)
picogram per kilogram (pg/kg)	7.0×10-12	grain per pound (gr/lb)
Volume
cubic centimeter (cm3)	0.0610	cubic inch (in3)
liter (L)	0.2642	U.S. gallon (gal)
milliliter (mL)	0. 001057	quart (qt)
Mass
picogram (pg)	1.543×10-11	grain, avoirdupois (gr)
milligram (mg)	0.01543	grain, avoirdupois (gr)
gram (g)	0.03527	ounce, avoirdupois (oz)
kilogram (kg)	2.205	pound, avoirdupois (lb)
Flow rate
liter per minute (L/min)	0.2642	gallon per minute (gal/min)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F= (1.8×°C) +32.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25°C).

Concentration units for chemical constituents in water are milligrams of solute per liter of solution (mg/L).

Concentration units for dissolution of a mineral in water are millimoles of dissolved mineral per kilogram of water (mmol/kg).

Concentration units for chemical constituents in rock are milligrams of constituent per kilogram of rock (mg/kg).

Concentration units for excess air dissolved in water are cubic centimeters per liter (cm³/L).

Concentration units for chlorofluorocarbon concentrations dissolved in water are picograms of chlorofluorocarbon per kilogram of water (pg/kg).

Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1929 (NAVD 29).

Horizontal coordinate information is referenced to North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.