Reed had followed fellow Yamaha rider Grant Langston and Suzuki's Mike Alessi through turn one, but others - including reigning champion James Stewart - weren't so fortunate, being caught up in a first corner pile-up.
Chad soon moved into the lead - only to slip back to fourth after stalling on lap two. But the Australian recovered quickly and was back up front by lap 5 of 20.
"I have been thinking about this race since last May," said Reed. "I knew I needed a good start tonight and had to fight. I have been working really hard, and this win shows that hard work pays off."
Stewart charged hard to reach the runner-up position by the halfway point, but could do nothing about Reed, who won by over 20secs.
"Someone clipped my wheel in the first turn, and I went down," said Stewart. "It was very slick out there. I give it up to Chad for this win. It's going to be a great season."
Ferry, Stewart's Kawasaki team-mate, completed the podium with Langston fourth and Honda's Kevin Windham - who also fell at turn one - fifth. Alessi finished sixth on his Suzuki AMA debut while Andrew Short (Honda), Nick Wey (KTM) and David Vuillemin (Suzuki) completed the top ten.
In the West Coast AMA Supercross Lites Championship, Suzuki's Ryan Dungey made an aggressive pass on Yamaha's Jason Lawrence to take the lead over the triple jump on lap seven of the main event. Lawrence then trailed Dungey closely until he crashed on lap nine. JL re-entered the race and was able to salvage second place.
"This is awesome," said Dungey on the win. "Coming from Minnesota, this is a huge win for me. I could not do this without my entire family. It was a great race, and we will see who comes out on top at the end of the season."
KTM's Justin Brayton was third.