Southeast Piscataquis, also known as Orneville, is an unorganized territory (township) in Piscataquis County, Maine, United States. The population was 254 at the 2000 census.
According to the United States Census Bureau, the unorganized territory has a total area of 38.1 square miles (98.7 km²), of which, 36.3 square miles (93.9 km²) of it is land and 1.8 square miles (4.8 km²) of it (4.83%) is water.
As of the census of 2000, there were 254 people, 101 households, and 73 families residing in the unorganized territory. The population density was 7.0 people per square mile (2.7/km²). There were 317 housing units at an average density of 8.7/sq mi (3.4/km²). The racial makeup of the unorganized territory was 98.82% White, 0.79% Native American and 0.39% Pacific Islander. Hispanic or Latino of any race were 0.39% of the population.
There were 101 households out of which 31.7% had children under the age of 18 living with them, 58.4% were married couples living together, 1.0% had a female householder with no husband present, and 27.7% were non-families. 19.8% of all households were made up of individuals and 9.9% had someone living alone who was 65 years of age or older. The average household size was 2.51 and the average family size was 2.78.
In the unorganized territory the population was spread out with 22.8% under the age of 18, 7.1% from 18 to 24, 26.0% from 25 to 44, 33.1% from 45 to 64, and 11.0% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 106.5 males. For every 100 females age 18 and over, there were 113.0 males.
The median income for a household in the unorganized territory was $28,036, and the median income for a family was $33,958. Males had a median income of $26,250 versus $23,750 for females. The per capita income for the unorganized territory was $11,940. About 15.9% of families and 27.4% of the population were below the poverty line, including 41.1% of those under the age of 18 and 13.3% of those 65 or over.