Volume and Weight

One inch of rain falling on 1 acre of ground is equal to about 27,154 gallons and weighs about 113 tons.

An inch of snow falling evenly on 1 acre of ground is equivalent to about 2,715 gallons of water. This figure, however, based upon the "rule-of-thumb" that 10
inches of snow is equal to 1 inch of water, can vary considerable, depending on whether the snow is heavy and wet, or powdery and dry. Heavy, wet snow has
a very high water content--4 or 5 inches of this kind of snow contains about 1 inch of water. Thus, an inch of very wet snow over an acre might amount to
more than 5,400 gallons of water, while an inch of powdery snow might yield only about 1,300 gallons.

One acre-foot of water (the amount of water covering 1 acre to a depth of 1 foot) equals 326,000 gallons or 43,560 cubic feet of water, and weighs 2.7 million
pounds.

One cubic mile of water equals 1.1 trillion gallons, 147.2 billion cubic feet, or 3.38 million acre-feet, and weighs 9.2 trillion pounds (4.6 billion tons).

Rate of flow (in a stream)

·        Water flowing at the steady rate of 1 gallon per minute is equivalent to: 1,440 gallons per day; 0.00223 cubic foot per second; 192.7 cubic feet per day;
or 0.00442 acre-foot of water per day.

·        Water flowing at the steady rate of 1 cubic foot per second is equivalent to: 449 gallons per minute; 646,000 gallons per day; 86,400 cubic feet per day;
or 1.98 acre-feet of water per day.

·        Water flowing at the steady rate of 1 acre-foot per day is equivalent to: 226 gallons per minute; 326,000 gallons per day; 0.504 cubic foot per second;
or 43, 560 cubic feet of water per day.

·        Water flowing at the steady rate of 1 cubic mile per day is equivalent to: 764.6 million gallons per minute; 1.1 trillion gallons per day; 1.7 million cubic
feet per day; or 3.38 million acre-feet of water per day.

Water Equivalents

1 cubic foot  =  7.48 gallons  =  62.4 pounds  
100 cubic feet  =  1 ccf (std. bill unit)  =  748 gallons  
1 acre-foot*  =  43,560 cubic feet  =  325,900 gallons  
1 cubic foot per second (cfs)  =  450 gallons per minute    
1 cfs  =  646,320 gallons per day    
1 cfs for 24 hours  =  1.983 acre-feet    
1 cfs for 30 days  =  59.5 acre-feet    
1 cfs for one year  =  724 acre-feet    
1 million gallons  =  3.07 acre feet    
1 million gallons per day (mgd)  =  1,120 acre feet per year    
1000 gallons per minute  =  2.23 cfs    
1000 gallons per minute  =  4.42 acre-feet per day    

Metric Equivalents      

15 million gallons per day (mgd)  =  56.775 megaliters pr day (ML/day)    
1 acre  =  .004 square kilometers (km)    
78,000 acres  =  312 square kilometers (km)    
120 square miles  =  193.08 square kilometers    
1 acre foot  =  1.233 million liters  =  1.233 megaliters   
1 ccf (one hundred cubic feet) or 748 gallons  =  2832 liters  =  2.832 cubic meters  
250 miles  =  402.25 kilometers    
450 miles  =  724.05 kilometers    
1 gallon per minute (gmp)  =  3.78 liters per minute    
1 pound per square inch (psi)  =  0.07031 kg/sq. cm    

*An acre-foot of water is enough to cover one acre of land one foot deep.