Complex sentence: The Homeowners Association--later, Thunderbird Property Owners Association--had been formed in 1969 and incorporated in 1971, and it began to investigate the possibility of taking over the water system itself.
Split into simpler sentences: The Homeowners Association (later, Thunderbird Property Owners Association) was formed in 1969 and incorporated in 1971. It began to investigate the possibility of taking over the water system itself.