I just found this Orange County Register article from 2003 about what they find when they drained the ROA for the first time in 10 years, and thought it might be interesting enough to share:
Orange County Register Michelle Gabriel 1/22/2003
Many guests are disappointed to find access to Tom Sawyer Island temporarily cut off.
Hard to say what the toaster was doing at the bottom of Disneyland's Rivers of America.
Sure, the cameras, beepers and video recorders make sense. But not the toaster. Or the full bottle of rum. The Rivers of America, which wrap around Tom Sawyer Island and hide underwater tracks for the Sailing Ship Columbia and Mark Twain Riverboat, is currently nothing more than a muddy, pipe-littered trough that won't be a river again until it is refilled in March.
The river was last drained in 1993 to repair the boats' underwater tracks and special-effects mechanisms that bring to life the Fantasmic show, which draws walls of water and leaping flames from the river, said Jack McClintock, a Disneyland spokesman.
Park officials drained it again Jan. 6, putting a stop to the boat cruises and cutting off access to Tom Sawyer Island. The island, a park staple since it opened to the public in June 1956, usually is swarming with children exploring caves and peeking around trees.
"The caves are closed!" 10-year-old Justin Sawhill said, crossing his arms and pouting. "That's the best part!"
Although Disney officials hid the bare riverbed with a 2,000-foot long, 8-foot tall blue fence, park guests still peeked through cracks. People stopped on an overpass above the Pirates of the Caribbean ride for a better look and peered from atop Tarzan's Treehouse, which soars 70 feet in the air, looking at grimy puddles and the ships, suspended on their tracks, masts peeping over the fence.
Some were surprised to see what was behind - or underneath - the rides.
"It's interesting to see the magic," said Brian Lopez.
McClintock said it took almost four days to drain the 6 million-gallon river. The water, which is dyed dark green - obscuring any toasters or toddies - is tested periodically for toxins, according to both park officials and the Santa Ana Regional Water Quality Control Board. The water is then emptied through the park's storm- drain system to the ocean.
To entertain guests until the Rivers of America are refilled, Disney employees dressed as Tom Sawyer and Becky Thatcher re-enact the fence-painting scene from "The Adventures of Tom Sawyer," inviting children to help them "whitewash" the fence with water-soaked brushes.
The riverboats and Tom Sawyer Island were among a handful of rides closed Tuesday.
The Haunted Mansion and the "It's a Small World" rides were closed, which limited what guest Jennifer Bronson could do with her 8-month- old daughter. The closed rides were slower paced than some of the rides left open - the jostling Indiana Jones adventure ride and Splash Mountain, which features a drenching five-story drop.
Jack Spiewak said he wished he could see more of the construction. As he squinted through cracks in the wall - his son, perched on his dad's stomach, got a peek as well - he said he wished there were a window in the fence.
His friend, Teri Vore, explained the voyeurism.
"We like the behind-the- scenes action," she said.