Crews in the City of Shasta Lake will be cleaning and inspecting the cities sewer system over the next month. Starting Thursday crews will begin the process of removing sediment, grease, and other debris from the sewer mains. After the cleaning is done the city will begin a video inspection of the pipes. In low lying areas and in some older homes residents may see what is called “toilet bubbling”. The phenomenon occurs when small amounts of water and air are forced back into toilet bowls. Residents are asked to leave the toilet lid down during the cleaning process. Notorists may experience brief delays as crews work through the city and are asked to slow down.