Protecting the Water Way

 is a Fallout 3 quest that is added to the game in the Broken Steel downloadable content pack.

Walkthrough
Basic quest summary:

Scribe Bigsley will ask the Lone Wanderer to investigate the organised bandit attacks on the Aqua Pura caravans. The Lone Wanderer will be asked to speak to a Rivet City officer to learn more details of the quest. Speaking to the officer on the ramp leading to Rivet City, the player is asked to catch up with a water caravan heading towards Canterbury Commons that has just left the Jefferson Memorial. Following the river around will lead the player to the caravan as it is in ambush by some bandits (this player has done this twice and was unable to save the anyone other than one of the guards both times). Upon searching any of the bandits the player will find an audio log from the bandit leader, instructing the bandits to group at Wilhelm's Wharf. When reaching Wilhelm's Warf, the Lone Wanderer can either speak to the bandit leader (the password is 'Mirelurk Cakes', however on mine it was "Mirlurk Stew" ) and pass a difficult speech challenge to persuade him to give up or else kill all the bandits. Sparkle can be found dead in the hut. The rivet city officer thanks the player for their assistance, but is unable to reward them. The wanderer is advised to speak to Scribe Bigsley in order to receive the reward - some enclave captured gear.