Lake Arthur is a town in Chaves County, New Mexico, United States. The population was 436 at the 2010 census.
Lake Arthur is located near the southern border of Chaves County at 32°59′58″N 104°21′55″W (32.999556, -104.365158), about 1 mile (1.6 km) west of the Pecos River. New Mexico State Road 2 passes through the town, leading north 9 miles (14 km) to Hagerman and south 11 miles (18 km) to Artesia.
According to the United States Census Bureau, the town has a total area of 0.54 square miles (1.4 km2), all of it land.
As of the census of 2000, there were 432 people, 134 households, and 107 families residing in the town. The population density was 789.2 people per square mile (303.3/km2). There were 149 housing units at an average density of 272.2 per square mile (104.6/km2). The racial makeup of the town was 62.96% White, 0.46% Native American, 0.69% Asian, 34.49% from other races, and 1.39% from two or more races. Hispanic or Latino of any race were 70.14% of the population.
There were 134 households, out of which 47.0% had children under the age of 18 living with them, 56.7% were married couples living together, 17.2% had a female householder with no husband present, and 20.1% were non-families. 17.9% of all households were made up of individuals, and 8.2% had someone living alone who was 65 years of age or older.