As I see the flooding of downtown Laguna again I recall the countless times retired (now deceased) Civil Engineer Gary Alstot showed the City Council what the problem is and how to fix it only to be put off for a variety of reasons. The problem is that the main large channel that runs from the canyon down to Beach Street is suddenly forced to run through a much smaller channel under town for a long block to empty in the ocean.
Of course when heavy rains occur all of that water in the main channel that ends at Beach Street cannot pass through that narrow channel under town and floods up over Beach Street and down Broadway and all over downtown. Alstot proposed to make a full-sized channel under Broadway down to the ocean that would connect to the existing large channel at Beach Street. This would have cured most of the dramatic flooding that occurs every few years.