In the book, Flush, Chapter 15-16, what is Operation Royal Flush? How is it going to work?

Operation Flush is the plan that Noah and Abbey come up with for their plan to expose the Coral Queen's dumping in the marina. Noah and Abbey put their money together, which totals fifty-seven dollars and sixteen cents. They will use this money to buy fuchsia dye (food dye) that wouldn't be harmful to animals.

From here, Shelley becomes an important part of the operation. She hides the dye on the boat, and then she helped Noah hide on the boat, after which she provided him access to the restrooms. Noah and Shelley both added dye to the toilets, which they then flushed. When the Coral Queen dropped its waste..... the dye would then fill the marina.