[2] Its watershed encompasses about 7,000 square miles (18,000 km2), and it supplies drinking water to about one-sixth of the population of the state.

The primary importance of the locks today is to maintain a pool that allows the city of Lexington to draw its drinking water from the river.

The main stem of the Kentucky River is formed near Beattyville in Lee County by the confluence of the North, Middle, and South Forks.

Approximately 15 miles (24 km) southeast of Boonesborough, the Kentucky is joined by the Red River.

At Frankfort, it is joined by Benson Creek; this confluence was the junction of Kentucky's three original counties.

At Monterey, approximately 10 miles (16 km) north of Frankfort, it is joined by Elkhorn Creek, which drains much of the Inner Bluegrass region.

[2] At Airdale, the North Fork has a mean average discharge of approximately 863 cubic feet per second, per data collected during the period 1930–1942.

[9] The river's narrow valley and surrounding rocky terrain cause rainwater to run off into many ephemeral creeks rather than being absorbed into the soil.

Swiss immigrant and lock-keeper Frank Wurtz recorded floods from 1867 on and spoke with local farmers to learn of earlier ones in 1817, 1832, 1847, and 1854.

[12][page needed] On January 1, 1919, the waters rose ten feet in as many hours at Frankfort, causing damage to many smaller towns along the river.

[12][page needed] Flooding in 1927 caused widespread damage to the Kentucky River basin in communities such as Neon, Whitesburg, and Hazard.

[15] While the public was still dealing with the effects of the flooding, Kentucky Utilities opened the Dix Dam spillways, which added 3 feet (0.91 m) to the floodwaters.

[12][page needed] Residents of the Kentucky River watershed demanded the federal government do more to control floods.

Kentucky Hydro-Electric had begun pushing as early as 1925 for a 162-foot (49 m) dam 1 mile (1.6 km) above Booneville on the South Fork, but this proposal was unpopular as the dam would create a reservoir backing up the South Fork for over 28 miles (45 km).

[citation needed] In 1939, President Franklin D. Roosevelt signed the Flood Control Act of 1938, which authorized the construction or study of many dams and reservoirs by the Army Corps of Engineers.

Only two small lakes, Carr Fork and Buckhorn, were created in the Kentucky River watershed.

[17] Several rural school buildings were entirely destroyed, and many others were closed either because of damage or because transportation disruption meant that people simply could not get to them.