Spores or no spores, you'd better find a way to clean out those basins. Not only do the basins not work well when full of silt, if they drain urban streets especially in industrial or heavy-traffic areas the sediment tends to accumulate metals and other contaminants. If they're not cleaned out every 2-5 years, the contaminants can build up to where you can't easily dispose of the material (i.e. might have to send it to Kettleman instead of whatever other use you were thinking of).

Are you're expecting the spore people to come after railroad upgrades in Niles Canyon? Don't they have plenty of better things to attack it with (several of which you've already described)?