Question: Plymouth Regional High School includes students from a town in Grafton County, New Hampshire that had a population of 247 in what census year?

Context paragraphs:
Huntington Union Free School District: The Huntington Union - Free School District is a school district in Huntington, New York.  There are eight schools in the district.  Students in kindergarten through grade 4 are situated at Flower Hill Primary, Jefferson Primary, Southdown Primary and Washington Primary Schools.  The Jack Abrams STEM Magnet School includes students in grades 3-6 from throughout the district.  Woodhull Intermediate School houses students in grades 5 and 6.  J. Taylor Finley Middle School serves students in grades 7 and 8.  Huntington High School serves students in grades 9 through 12.

Peters Township High School: Peters Township High School is a public high school in McMurray, Pennsylvania, United States.  It was built in 1968 and renovated in 1981.  In January 2001, a 16-month, $24 million renovation was completed.  The high school includes students from grades 9 through 12.  It is located about 15 miles south of Pittsburgh.

O'Bannon High School: Norma C. O'Bannon High School (known as O'Bannon High School) is a public junior and senior high school located in unincorporated Washington County, Mississippi, USA, adjacent to Greenville.  The school is part of the Western Line School District.  The school includes students in grades 7 through 12.

Northern Valley Regional High School at Demarest: Northern Valley Regional High School at Demarest is a comprehensive four-year public high school serving students from several municipalities in Bergen County, New Jersey, United States.  The high school serves students from the suburban communities of Closter, Demarest and Haworth.  The school is one of two high schools that are part of the Northern Valley Regional High School District, the other being Northern Valley Regional High School at Old Tappan, which serves students Harrington Park, Northvale, Norwood and Old Tappan, along with students from Rockleigh, who attend as part of a sending/receiving relationship.

Plymouth, New Hampshire: Plymouth is a town in Grafton County, New Hampshire, United States, in the White Mountains Region.  Plymouth is located at the convergence of the Pemigewasset and Baker rivers.  The population was 6,990 at the 2010 census.  The town is home to Plymouth State University, Speare Memorial Hospital, and Plymouth Regional High School.

Timberlane Regional High School: Timberlane Regional High School is located in Plaistow, New Hampshire, and serves as a regional high school for the towns of Atkinson, Danville, Plaistow, and Sandown, New Hampshire.  The school was built in 1966 and is a part of the Timberlane Regional School District.  Timberlane Regional High School is a co-educational school for grades 9-12.  The school has won the 1996, 1997 and 2014 Excellence In Education Award.  As of 2005, the school has approximately 1,400 students on roll.  The school mascot is the owl.  The school is regionally accredited for its award-winning wrestling team, which holds 23 NH State Wrestling Champions titles, as of 2015.

Australian International School Singapore: The Australian International School (AIS), in Singapore is a co-educational international school in Singapore.  The school is owned by Cognita.  AIS is made up of three sub-schools; Early Years, an Elementary School and a Secondary School.  Early Years is for children aged 18 months to 5 years.  The Elementary School includes students in Prep to Year 5.  The Secondary School includes Year 6 to Year 12.

Waterville Valley, New Hampshire: Waterville Valley is a town in Grafton County, New Hampshire, United States.  The population was 247 at the 2010 census.

Plymouth Regional High School (New Hampshire): Plymouth Regional High School (PRHS) is a public secondary school in Plymouth, New Hampshire, United States.  Surrounding towns that attend PRHS are Ashland, Holderness, Campton, Rumney, Wentworth, Warren, Ellsworth, Waterville Valley and Thornton.  Bruce Parsons is the current principal.  The facility, opened in 1970, is located on Old Ward Bridge Road in Plymouth.  It also housed Plymouth Elementary School until 1990.  Plymouth Regional was known as Plymouth Area High School until 1991.  The school colors are navy blue and white.

Warren Hills Regional High School: Warren Hills Regional High School is a four-year public high school located on Jackson Valley Road in Washington Township in Warren County, New Jersey, United States, operating as part of the Warren Hills Regional School District.  The school offers a comprehensive education for students in ninth through twelfth grades.  The student population includes students from Franklin Township, Mansfield Township, Oxford Township, Washington Borough and Washington Township.

Supporting paragraphs: Plymouth Regional High School (New Hampshire) Waterville Valley, New Hampshire
Answer: 2010