Indiana-based Beacon Health System has reached a definitive agreement to acquire the Ascension health care system in Southwest Michigan. The agreement, expected to close this summer, includes the acquisition of four hospitals, 35 outpatient clinics and an ambulatory surgery center. The hospitals being acquired are: Ascension Borgess Hospital in Kalamazoo; Ascension Borgess Allegan Hospital; Ascension Borgess-Lee Hospital in Dowagiac; and Ascension Borgess-Pipp Hospital in Plainwell.