The 'Noah' actor and his sons Charles, nine, and Tennyson, six, watched the vehicle career out of control on their farm, crashing through a fence before coming to a watery standstill.
Revealing the incident on his Twitter account, Russell said: "What a morning #1... Farm staffer jumps out of truck, top of the hill, handbrake fails, trucks careens through a fence, 300m into a dam.
"Steep on that hill, truck took out two panels of post and rail, immediate momentum, missed everything, hole in 1 to the dam
"What a morning #2 boys and I follow it's path of destruction, as it is sinking, windscreen wipers keep going, good advert for Toyota (sic)"
Despite the potentially-serious incident, the truck was retrieved without damage and little Tennyson hailed the drama as the "best day ever".
In other tweets, Russell added: "Wam #3... brother arrives with the John Deere, gets in freezing dam to hook up the truck, beautiful job retrieving the submarine.
"Wam #4 Youngest announces "best day on the farm ever"... no one hurt, only pride. Told old mate,"days like this'll get you a new nic name
"Wam #5 In a dry, Australian acceptance of the inevitable, old mate squints to the middle distance and softly states, "yes, they do" (sic)"