Rosilyn Lake Then & Now

What ever became of the muddy old pan known as Rosilyn Lake? Rosylin Lake sat in the foothills between Sandy Oregon and the Dodge Park area of the Sandy River basin. The lake was drained when Marmot Dam came down in 2007/2008.



Now Removed Marmot Dam



Used mostly as a put and take trout fishing lake for local Sandy and East Portland residents. The only native fish the lake contained had been mud sucker and possibly native smolts that most likely entered the lake via the water diversion channel from Marmot. The lake was part of the Bull Run Hydro Electric Project. Water diverted from the Sandy River via Marmot Dam flowed into the lake through a series of man made water channels and tunnels that carved through the mountains in between, one of wich is now said to contain a sensitive Northwest Bat species.

I had fished in the lake for many years and photographed the area many times during my visits. Here is a small collection of photos that show the lake, the drying event and now the dry basin left behind. Although it may seem sad in some ways to loose this close in put & take fishery, we gained better passage for native [and hatchery ....] fish to reach the upper Sandy basin where the best spawning gravel in the system lies.

Back Then

Scenery Photos Shot with Infared Filter





Draining the Lake









Most of the fish we see in these photos are mudsuckor. They most likely migrated into the lake through the Marmot diversion channel. I suspect by this point most trout had been fished out by predator birds and raccoons.

And Now

The red dirt you see was brought in from some other location to be used as land fill.









The trashrack hole is filled in now for safty and the structure that use to return the lakes water back down to the Bull Run power house has been removed. Water from the lake no longer adds to the flow of the lower Bull Run River. This also created a higher water flow in the main Sandy River in the section between the Bull Run mouth and the old Marmot Damn site.



I can say I have some fond memorys of this lake through the 90's and 2000's. There was a hex hatch here that no one ever fished. The large yellow may flies simply loved the mud silt bottom this lake had. I tied many imitations to fish this hatch and at times it fooled the larger hold overs that had of course acclimated to the natural food sources.

Other days spent drifting across the lake in a drift boat dragging an "off the bottom" power bait rig accounted for easy limits of hatchery trout. Bank fishing with bait here always seemed a little fusy but by July I could look to the hex hatch for better catches.

I hate to see any good local fishing spot go away but in this case the given return should in the long run be worth so much more. Doing each little step we can to restore the balance that these senitive salmon & steelhead runs keep insisting we acknowledge they so desperately need.