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Canyon Lake Statistics (return)

Earth Dam
Completed in 1964
Surface area = 8240 acres
Normal Storage = 386,200 acre feet
Maximum Storage = 1,129,300 acre feet
Maximum Discharge = 502,800 cfs
Drainage area = 1425 square miles
Dam Length = 4410 ft
Dam Height = 224 ft

What Do the Flow Numbers Mean

Maximum Storage
Maximum storage, in acre-feet, which is defined as the total storage space in a reservoir below the maximum attainable water surface elevation, including any surcharge storage.

Normal Storage
Normal storage, in acre-feet, which is defined as the total storage space in a reservoir below the normal retention level, including dead and inactive storage and excluding any flood control or surcharge storage.

Source - Army Corps of Engineers Website

What do the numbers mean? 

River flow is given in cfs (cubic feet per second),
Pumping rates in gpm (gallons per minute)
Water allotments to water companies in acre feet per year. 

News paper articles usually note that one acre foot is equal to 325,851 gallons or the normal amount of water used by two families of 4 in a year.   That is a little less than 450 gallons a day or 13,500 gallons a month per family.

But what does it mean when Canyon Lake water supply is allotted 4000 acre feet per year of water from Canyon Lake or GBRA is granted another 40,000 acre feet per year of Canyon Lake water?  What flow rate is needed from the Guadalupe River to replace that water?

What does it mean when Southeast Trinity Underground Water District is given permitting authority on wells that pump over 17 gpm?

These tables will help answer these questions for you.