After six years serving the towns of Groveland, Merrimac, and West Newbury, Pentucket Regional School District Superintendent Jeffrey Mulqueen, 60, is retiring at the end of the school year. The district has four elementary, one middle, and one high school with a student population of 2,498 in 2017. There will be interesting challenges facing his replacement, as black mold was discovered at Page Elementary School in West Newbury this month, forcing the temporary relocation of students to other district schools in Groveland and Merrimac. The district also is currently working with the Mass. School Building Authority on plans to build a new high school.Linda Greenstein can be reached at firstname.lastname@example.org.