The board's response was due to Secretary of Education-designate Hanna Skandera on Tuesday and delineated the multiple reasons the district would be better off to stay unified.
"The bigger the district, the more resources you have," said district Superintendent Don Levinski, backing the board's decision.
By a 3-1 vote, the board approved the 23-page letter. Boardmember Randy Manning voted against it and member Hoskie Benally was not present.
The letter argues against the proposal of Children First, a Kirtland-based group which in January gathered more than 3,000 petition signatures to move forward the possibility of a separate school district.
The proposed district would break the Central Consolidated School District at the reservation line, though it would possibly include the Ojo Amarillo area, which is past the line.
Children First gathered support from more than 60 percent of the registered voters in the proposed district area.
In response, the board drafted its own letter, approved it on Tuesday and expects it to be on Skandera's desk today.
The letter outlines a handful of arguments that center on the board's belief that a split district would not be a costly undertaking, but also would add stress to community efforts to nurture culture in the Kirtland and Shiprock area.
"I see some biased inaccuracies," said Manning, who requested that the board discuss the letter in an open session before approval. Initially, it was to be discussed in a closed session.
The letter will be reviewed before the May 16 public hearing, during which the Public Education Department will assess the public's views on the matter. The hearing will be from 1:30 to 4:30 p.m.
Children First also will be allowed to submit a rebuttal if it chooses.
"The Kirtland group has not offered any substantial reason to divide the Central Consolidated School district that meets the requirements of state law," said the district's board president, Matthew Tso, in the letter.