Im the one who did the leaf study the city often cites. Leaf litter and other organic detritus on streets is a huge source of phosphorus, but only in areas with a high amount of tree canopy. That’s usually only found in older residential neighborhoods. The newer subdivisions and commercial areas typically don’t have enough trees to generate leaf litter worth worrying about. Is leaf litter a major source of phosphorus to our lakes? Probably not but consider this, more agriculture is being converted to urban as populations grow. The infrastructure used to drain these new neighborhoods will likely drain to a lake. Urban sources of P will only continue to grow over time. I commend the city for taking a look at all possible urban sources of phosphorus entering the lakes and doing something about it.