More like a build-up of dirt/dust, possibly with a little water. Very common on 113s and some M-250R2s and OVZs here. I'm surprised this has a plastic lens. Virtually everything up there is glass!

I hear nests are common in these things, especially the path lights.

Yes but unless there's a hole in the refractor there's no way for the nest to be built. There are no holes large enough to let anything in aside from dust or water, which would carry dirt from inside the light with it and into the refractor, since the refractor is the lowest point of the fixture. Looks like it could possibly be a pile of dead flies/moths too lol. I've seen that here. There's a Model 113 here that is filled to the brim with water and after a big storm it was windy and the arm was shaking a little and water was dropping out of it. And the thing still works too! I had reported it for being full of water and all they did was change the refractor and stick a new lamp and PC in it (the fixture worked fine before too, no need for a new lamp and PC but they did it anyway). And the next time it rained heavily the refractor filled up again. Those 113s are prone to collecting water it seems.

Here's a 113 filled with brownish water with some crap that settled down at the bottom. And no, the refractor is not browned out since they used acrylic ones here, which do not discolor.

Kinda interesting looking fixture, its like a shoebox but with a normal drop lens stuck on it

I've seen little piles of 'stuff' like this in lights, to me it looked like a collection of dead bugs. Seems bugs can make their way into the tinyest of spaces, probably allot of lights don't seal well enough to keep them out...

I wonder why this one has a plastic lens. Mine has a glass lens. I believe they're pretty well sealed up too. There's a bird guard at them opening for the arm and the optics have a felt like gasket.

I think Brampton uses a small time electrical contractor for park lighting that spends more time restoring lights, and they save and use all kinds of refractors in this fixture and the powerlight equivalent. I saw a knock down pole replaced with a powerlight equivalent fixture+dirty old plastic refractor the other day. Either fixture is discontinued, so I guess that's why these are sometimes replaced with FCO shoeboxes now also.

I only see the glass lens on a few of them. The only FCO ones I know of are on the Etobicoke Creek Trail between Sandalwood and Conservation Dr.

There was a knockdown by the Howden rec centre, they replaced it with a powerlite looking fixture. (it looks brand new) and they have a round concrete pole on the ground beside it and a "new old square pole" was put up. I am not 100% sure if its the same old pole or not though. I do remember the old pole leaning towards the path now its leaning backwards

Interesting, the knockdown replacement I saw the other week got a new round pole with the same powelite looking fixture you saw at Howden rec centre, and I also thought it was new because it looked like there is no rusting. I looked closer and noticed the corners are a little beat though. I wonder where this fixture came from because it is in better condition than any other powerlights in the city, yet I don't think they repainted it because a corner is a bit rough.

Yep, the Etobicoke Creek trail has had a lot of spot replacements the past few years. I've seen new FCO shoeboxes spot replacements on richevale trail at Sandalwood, and a parkette off Braidwood lake rd. Those places are close to the etobicoke creek trail interestingly.

The creek trail seems to be made up of these Cooper shoeboxs now. The roundabout at loafers lake I think was all the powerlite types still. That trail is pretty much Cooper shoeboxs from loafers down to Williams then Cooper shoeboxs again from Queen st to the end by Steeles.