These lakes and others, along with an extensive floodway system of levees, are operated in a coordinated manner to minimize flooding along the Trinity River floodplain corridor in the Dallas/Fort Worth Metroplex.

A second major influence for development was the desire of commercial interests for a shipping channel along the length of the Trinity River.

This project, in its most grandiose design, was envisioned as a 9-foot-deep (2.7 m) by 150-foot-wide (46 m) canal (2.74 × 45.72 m) running upstream from Trinity Bay on the Gulf Coast to Dallas, and west all the way to Fort Worth.

Construction of Benbrook dam began in May 1947, and was practically completed when floodgates were closed and deliberate impoundment was begun in September 1952.

One design option considered during the planning stages for the lake included an alternate damsite near the current I-20 bridge over the Trinity River, 3.7 feet (1.1 m) downstream from the final, chosen location.

Flooding in May 1949 claimed eleven lives in Fort Worth and cost $11 million to local businesses, as construction for the dam was beginning.

During this flood, the lake filled to its 694-foot (212 m) conservation level for the first time on May 12, 1957; the spillway elevation of 710 was reached on May 26 that year, with a record pool of 713.35 on June 6, 1957.

In other words, flooding is not eliminated, but its location is predetermined—it will be along the undeveloped lakeshore area upstream of the dam, rather than along the industrialized or populated downstream river valley.

When waters rise too quickly to be released by this method, then the lake may flow over the uncontrolled spillway at the northwest end of the dam.

Spring rains in 1957 first filled the lake to its normal conservation pool elevation of 694 NGVD (National Geodetic Vertical Datum or feet above sea level) for the first time.

The drought ended with heavy rainfall in the spring of 1989, and over the next 11 months the lake reached record high levels on two occasions.

These floods closed all the parks and recreation areas on Benbrook Lake for almost all of those two years, heavily damaging the facilities and shoreline, but saving hundreds of millions of dollars in Fort Worth downstream of the dam.