Karst, floods and freezes: a Lexington homeowner's field guide
Three things explain most of the water damage in Lexington houses. The limestone under the lawns, the way the city's creeks were paved over and piped, and a winter that can swing fifty degrees in half a day. This guide covers each, with the public sources linked.
Referral service, not a contractor. Your request goes to an independent Lexington-area restoration company. We do not do the drying or repairs.
The ground: limestone with holes in it
The Kentucky Geological Survey's groundwater atlas for Fayette County, written by KGS geologist James C. Currens, opens with a sentence that explains a great deal: "Much of the state's beautiful scenery, particularly the horse farms of the Inner Bluegrass, results from the development of karst landscape." Karst is ground formed by the slow dissolving of limestone. Its features are sinkholes, sinking streams, caves and springs.
The same atlas lists Lexington, Georgetown, Winchester, Versailles and Nicholasville among the Kentucky cities that are "partly or entirely underlain by karst." It describes the Inner Bluegrass, "surrounding Lexington," as the second largest karst area in the state. Statewide, 92 of Kentucky's 120 counties have at least some karst, and about 40 percent of the state sits on rock that can develop it. Not every town nearby shares that ground: the KGS places most of Madison County in the Outer Bluegrass, with shales and siltstones mixed in among its limestones. The Berea page covers that edge of the area.
A KGS research summary reports that 1,821 sinkholes were identified in Fayette County from lidar data. Many are shallow enough that nobody notices them until it rains hard.
How a sinkhole floods a house
According to the KGS atlas, a sinkhole is "any depression in the surface of the ground into which rainfall is drained." Water leaves it through a throat into the rock. The throat is often roofed over with soil and broken rock, and can be partly or completely filled with rubble. When it is plugged, a temporary pond forms.
The atlas names two risks for buildings. "Structures built in sinkholes are often vulnerable to flood damage." And homes built over filled sinkholes "may be damaged as the fill is transported out of the sinkhole and the soil cover collapses." It also warns that waste dumped into sinkholes can easily reach underground streams, which matters if anyone is tempted to drain a flooded basement into one.
The water: seven watersheds and a buried creek
Lexington's Division of Water Quality says the city has seven urban and two rural watersheds. Its watershed pages list Cane Run, East Hickman, North Elkhorn, South Elkhorn, Town Branch, West Hickman and Wolf Run. Three of them say a lot about where water goes.
260 square miles, in karst
Covers central and northwest Fayette County and flows to South Elkhorn Creek. The city counts three known karst basins in it: the Silver, Lindsay and Mystery. The creek itself, Lexington's first water source, runs in a culvert under Vine Street.
10 square miles, half paved
Southwest Lexington just inside New Circle Road. The city says almost half of the watershed is impervious surface, so rain runs off rather than soaking in.
45.4 square miles of sinkholes and springs
Spans Fayette and Scott counties, with many karst features. Its Royal Spring karst basin is the water supply for Georgetown.
The sewer side
The sanitary sewer has 81 pump stations, more than 1,400 miles of pipe, and two treatment plants, Town Branch, opened in 1919, and West Hickman, running since 1972. Overflows from that system were the subject of a 2008 federal settlement and a consent decree the city says was finalized in January 2011. Work under it is still under way; the sewer backup page has the details.
The storm side
Every Lexington property pays a monthly Water Quality Management Fee for stormwater work. A single-family home pays one ERU, an equivalent residential unit of 2,500 square feet of paved or roofed area, which is $6.18 a month from July 1, 2026. Part of the fee funds incentive grants, and one stated goal of the grants is reducing runoff and flooding.
Rivers at the county line
Jessamine County's southern edge is the Kentucky River, in a gorge a 1993 KGS report describes as up to 400 feet deep. In the April 2025 storms, the river at Camp Nelson rose to a record 47.04 feet on April 6, above the old record of 46.02 feet from May 2010. At High Bridge it reached 47.13 feet, its third biggest crest on record there; the record is 53.10 feet from December 1978. Nicholasville's water plant draws from that same river.
Flash floods in town
In town, the danger is speed rather than rivers. On June 22, 2026, the National Weather Service reported 2.5 to 3 inches of rain in under ninety minutes in Lexington-Fayette County. Five days later the governor declared a state of emergency over flooding across the state, according to the Kentucky Department of Insurance.
The cold: fast swings, split pipes
Lexington is not a deep-cold city most of the year, which is part of the problem. Houses are not always built for the few days when it gets very cold, and the swings are fast.
- December 22 to 23, 2022: temperatures fell 50 degrees in 12 hours; Lexington's low was 5 below zero on the 23rd; wind chills reached 30 below. NWS Louisville
- January 21, 2024: Lexington fell to 7 below zero, then reached 64 degrees four days later. NWS Louisville
- 2024 as a whole was the warmest year on record at Lexington. NWS 2024 summary
- Kentucky American Water's advice: know where the main shutoff is, trickle faucets on exposed pipes, and keep the heat at 55 degrees or higher when away. City of Lexington, January 2024
A warm average year does not protect pipes from a two-day Arctic outbreak. The pattern to watch for is the one in both of those events: a sharp drop to near or below zero, often with wind, followed by a quick thaw. The leak shows up during the thaw, often in a wall or ceiling nobody has looked at in years. The burst pipe page covers what to do in the first hour.
What this means for a water damage job
- Find the source before drying. In karst ground, water in a basement may be groundwater, runoff, a sinkhole backing up or a sewer. Each needs a different fix.
- Expect slabs to dry slowly when the ground outside is saturated, even after the standing water is pulled out.
- Treat flash flood water as contaminated, because it has crossed streets and yards and sometimes mixed with sewage.
- Do not drain into a sinkhole. The KGS notes that waste dumped there can reach underground streams.
Three lookups worth doing
- Your flood zone, through the FEMA Map Information Exchange or the LFUCG Flood Hazard Zone Viewer, from the city's floodplain page.
- Whether your sump pump discharges to the storm side or the sanitary side. The city pays up to $3,000 to disconnect one found tied to the sanitary sewer.
- Whether your house is in a sinkhole or on a filled one. Older plats, a survey, or simply watching where water stands after a storm will tell you.
Local questions
Who do I call about a sinkhole that floods my yard?
If it is affecting a street, a storm drain or public land, report it to LexCall 311. A sinkhole entirely on private property is usually the owner's to manage. If you see a new hole open up, the Kentucky Geological Survey collects reports of cover-collapse sinkholes on its karst pages. For water that got into the house, a restoration company handles the drying.