1980 North San Gabriel Dam and Lake Georgetown upstream of Georgetown, TX

(Satellite)

usace, p2

"The North San Gabriel Dam is approximately 6,650 feet (2,027 m) long, 162 feet (49 m) high....The reservoir has a normal storage capacity of 37,100 acre-ft (45,762 Ml) and maximum capacity of 236,500 acre-ft (291,718 Ml). The surface area of the reservoir is 1,310 acres (530 ha) and the total catchment area is 246 square miles (637 square kilometres). The dam has a 1000 feet (305 m) wide uncontrolled spillway with a maximum discharge capacity of 342000 cubic feet per second (9684 cubic metres per second)." [DamsOfTheWorld]

Conservation pool is 791', and flood pool (spillway elevation) is 834'. Maximum design water surface is 856.2', and the top is 861'. [twdb]

USACE, Fort Worth District posted four photos with the comment: "Deliberate impoundment began at Georgetown Lake #OTD in 1980. Originally called the North Sam Gabriel Dam when construction began in 1972, the lake sits in the Brazos River Basin. The dam is 6,700 feet [2km] in length with a maximum height of 164 feet [50m]."

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July 4, 2025, Flood

A bunch of thunderstorms trained over Central Texas on the morning of July 4, 2025, causing flash floods that killed at over 100 people. The San Gabriel River also got lots of water.

I've learned that "full" is considered conservation pool. So, the dam can hold 236,500/37,100 = 637%. And the lake fills slower as the elevation goes up because there is more land to spread out on.

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