Hollis Mulwray learned about the illegal dumpings and was investigating them himself. Jake witnessed water being dumped for the first time when he was following Hollis; the duct behind him starts to spill water into the ocean. When Jake later goes to investigate the deaths of Mulwray and the allegedly drunk homeless man, he gets confirmation from a young local boy that the LA river has recently been used to divert water, as well as some other places. When he investigates Oak Pass Reservoir, where Hollis' body was found, he nearly drowns when a large amount of water is drained through the spillway he was hiding in. He confronts Mulwray's successor, Mr Yelburton, with this information, but Yelburton replies that they are courteously diverting some water in order to help orange farmers in the San Fernando Valley, and that some of the water is spilled in the process. However, when Jake goes to the farmers to confirm this story, they tell him that not only is LA's Water & Power Company cutting them off from natural water, they are even sabotaging their few remaining water storage tanks and wells in order to drive them away from the land.
Jake later finds out that all the farming land in the Valley that has become worthless due to the drought is bought up cheaply by the people around Noah Cross. Their intention is to re-irrigate the area as soon as they own it all, making the land fertile and valuable again. However, for that, they need the new dam and water reservoir to be built, which requires the approval of the city and a positive vote from the Citizens' Committee. That would only work if there was a genuine water shortage in LA. Apparently, the water company is doing too good a job in stealing water away from the surrounding valleys; so much that they have to illegally dump some of it from time to time to maintain their claim that there is indeed a water shortage. Mulwray was opposed to the new dam and reservoir because he knew that due to the widespread corruption, the new dam would be unsafe and another accident waiting to happen; but another reason for him was that he suspected that the water company was artificially creating a demand for it, and only Noah and his people would profit highly from it. And that's why he was killed for it.