Lewisville Lake, the Elm Fork and the 2015 High Water

What is Lewisville Lake and how did it come to be?

Lewisville Lake is a U.S. Army Corps of Engineers reservoir on the Elm Fork of the Trinity River in Denton County, covering 29,592 acres. The Corps built the Garza-Little Elm Dam between 1948 and 1954 for $23.4 million, and the 32,888-foot Lewisville Dam was completed in 1955.

The lake lies in southern Denton County, the Lewisville Lake area. It was first called the Garza-Little Elm Reservoir. The old Garza Dam was breached in 1957 to let the lake fill, and Congress named the structure Lewisville Dam in 1955 in a bill from Rep. Frank Ikard.

The year the lake itself was renamed is disputed between sources, so we do not print one. What is not disputed is the name's reach. The city of Lake Dallas takes its name from the lake's original name, and four small towns, Lake Dallas, Hickory Creek, Shady Shores and Corinth, are known together as the Lake Cities.

Reservoirs like this one typically hold water for use and hold back storm water. The second job is the one that was tested in May 2015. We do not say which cities draw drinking water from the lake, because we could not confirm it.

What happened on May 31, 2015?

Early on Sunday, May 31, 2015, Lewisville Lake rose to a pool of record at 537.02 feet. That is about 15 feet above the 522-foot normal pool and just over 5 feet above the 532-foot spillway top. Water flowed over the spillway and flooded streets below the dam, but did not enter structures.

May is typically the wettest stretch of the year in North Texas. When the pool climbed past the spillway top, water went over the spillway, and streets in areas below the dam flooded. Reports at the time said the water did not enter structures.

We lean on that last point. The sources we found give no town-by-town list of who flooded and who did not. We therefore say nothing about homes in any named town taking lake water in 2015, and you should be wary of anyone who does.

The timing is worth noting. May 31 was a Sunday, and the record came in the early hours. Nothing we found says what people knew when, but a rise that peaks overnight is a good argument for checking your coverage before a wet spring, not during one.

What did the roughly $150 million of dam upgrades involve?

The 2015 episode helped win about $150 million of upgrades by the Corps of Engineers at the dam, with roughly half of it for the spillway. Describe it as dam safety work. It does not mean the dam was unsafe, and our sources do not itemize the work beyond the spillway share.

The 2015 high water helped win the money, and the Corps went on to fund work at the dam, about half of it for the spillway. That is the whole of what we can say with sources, and we cannot itemize the rest.

The wording matters. The main dam work was finished in the 1950s, and upgrades are a normal part of managing an older structure. Spending roughly $150 million does not tell you the dam was unsafe, and we do not claim it was.

For a homeowner, the practical point is simple. A record year led to money being spent on the spillway, and your own share of the job is your drainage, your coverage and your plan. The Corps' Fort Worth District is, as best we can tell, the office that handles the lake. Check the Corps' own site for current lake levels and project news.

Who lives around the lake, and what lies downstream?

The shoreline touches Lewisville, Highland Village, The Colony, Little Elm, Lake Dallas, Hickory Creek, Lakewood Village and Oak Point. Below the dam, the Elm Fork runs toward Carrollton, Farmers Branch and Dallas, and it has limited capacity in big rains. Street flooding in 2015 was reported in areas below the dam.

Each lakeside town has its own story. The Colony has about 23 miles of shoreline, including two peninsulas, and calls itself the City by the Lake. Lakewood Village covers 1.44 square miles, of which 0.95 is water. Shady Shores began as a 1920s fishing camp of about ten cabins, and Lake Dallas and Hickory Creek share the lake's early development.

Lake-adjacent homes face a particular question: the lake itself. Older, smaller lots sit beside newer houses in some shoreline towns, and shoreline exposure varies a lot by lot. We could not verify exposure by town, so read your own survey and your insurer's flood map, and do not generalize from a neighbor.

Downstream is a different picture. Denton Creek and the Elm Fork are part of Carrollton's geography, and the Elm Fork, unlike the main Trinity, has limited capacity in big rains. Flash flooding at low spots and creeks is a spring pattern, and May is typically its peak. See our pages for The Colony and Lake Dallas for the local picture on each side of the lake.

Does homeowners insurance cover lake or creek flooding?

Usually not. A standard homeowners policy often excludes flood, meaning surface water from lakes, creeks and overloaded drains. Flood coverage is a separate policy through FEMA's National Flood Insurance Program or a private insurer, and new policies generally take about 30 days to start. Ask your agent, and remember your insurer decides.

The line insurers draw is between water from a failed pipe and water from outside. A burst supply line is usually a homeowners claim, if the policy covers it. Rising lake water, creek overflow and storm water entering at the doors are flood, and they are treated differently.

Waiting periods are the catch. NFIP policies generally take about 30 days to take effect, so a policy bought on the day the lake rises will not help. That figure is standard FEMA wording, and your agent can confirm the current rule. FEMA's FloodSmart site explains the program.

We promise no insurance outcome. What the crew provides is documentation: moisture readings, photographs and a list of removed materials, handed to you for whoever is handling the claim. The insurer decides what the policy covers. Our homeowners insurance and water damage in Texas guide goes through the sudden, long-term, flood and sewer distinctions.

What should lake-side and creek-side homeowners do before and after high water?

Before: confirm your flood coverage and its waiting period, keep gutters and drains clear, know your main shutoff and photograph your belongings. After: stay out of floodwater, treat it as contaminated, photograph everything before it is moved and call a restoration crew to extract and dry. Floodwater is Category 3 water.

Preparation is mostly paperwork and habits. Check what your policy says, and ask about flood separately. Walk your lot and see where water would go: low yards, garage doors, patios and stairs into walk-out homes are the usual first places. Few North Texas homes have basements, so window-well flooding is rare.

During an event, safety comes first. Stay out of moving or standing floodwater, keep away from outlets and appliances in wet rooms and do not drive through water on a road. If it is safe to reach the panel, turn off power to the wet area.

After high water, assume the water is contaminated. Rising floodwater from lakes, rivers and creeks is Category 3 water, the same class as sewage, and it carries dirt and bacteria. Porous materials such as carpet, pad and insulation that were soaked are usually removed and not dried. Put on boots and gloves, and keep kids and pets away.

Photograph first, then clear. Take dated pictures of the water line, the floors and your belongings. Call your insurer early. Our flood damage cleanup page describes the extraction and drying that follows.

• Ask your agent about flood coverage and its waiting period before spring.
• Clear gutters and keep downspouts discharging away from the foundation.
• Know where your main water shutoff is and how to close it.
• Photograph rooms and valuables, and keep the photos off site.
• After water arrives, photograph the water line before moving anything.
• Treat floodwater as contaminated and avoid contact.

What happens after floodwater leaves the house?

The crew extracts standing water, removes soaked porous materials, cleans and treats surfaces, then dries the structure with air movers and dehumidifiers until readings are dry. Mold is a risk if drying lags. In Texas a separate licensed assessor writes any mold plan, and a separate licensed remediator carries it out.

The order is extraction first, then removal of what cannot be saved, then cleaning, then drying. Flood cleanup is heavier than a clean-water leak because of the water category, and the crew sets up with protective gear.

Mold is a follow-on risk. EPA guidance says to dry water-damaged areas and items quickly to prevent it, and we cannot verify the exact hour count, so do not wait. Some people with allergies or asthma react to mold, which is one more reason to dry fast. If it appears and covers 25 contiguous square feet or more, Texas requires a licensed remediator working to a protocol from a separate licensed assessor.

Repairs come last and are quoted after drying. Permits matter too: plumbing and electrical repairs generally need a city permit and inspection, so ask your city's building department. After the February 2021 freeze, Lewisville waived permit fees for storm repairs but still required permits and inspections, a reminder that storm status does not skip the rules.