It is declared to be the policy of the legislature of the state of Idaho to authorize and mandate the department of health and welfare to develop and coordinate services for developmentally disabled persons through adult and child development programs and through contracts with rehabilitation facilities. The complexities of developmental disabilities require the services of many state departments as well as those of the community. It is the intent of this chapter that the department of health and welfare will cooperate with recognized agencies, organizations and departments in implementing this chapter. Services should be planned and provided as a part of a continuum. A pattern of facilities, services and eligibility should be established which is sufficiently complete to meet the needs of each developmentally disabled person regardless of age or degree of disability, with consideration of the family.