ERO Report 2023

An assessment of Elevated Riparian Optimization (ERO) structures on the South Fork of the Kinni, Hay Creek, and Cady Creek,  5-years post installation 

By Loren Haas

Hungry water is copious amounts of water not heavily laden with silt which provides extra energy and carrying capacity for sand and silt. Typically occurring in the spring, frozen soil helps minimize runoff erosion. Heavy snow accumulation and a late thaw made for one of the best spring scouring events in recent years. 

Flooding on the South Fork of the Kinni this spring has flushed out the sand below each of the EROs. Last year’s partial deposition is gone and the deep holes are looking much deeper and longer than ever. All of the EROs except one produced fish. One ERO that has a flat rock wedged in between the anchor rocks provides narrowing high velocity and redirected water and has accidentally produced my favorite spot on the creek to catch fish. 

Additionally, 3 more lunker structures have been partially exposed for the first time in many years. One is below an ERO, the others are upstream of the other 9 EROs. I expect this condition to be temporary as summer rains bring more sediment from upstream and rebury them. We will see. Pocket water sixteen inches deep or more has reappeared upstream of the EROs. It is still impossible to cast due to all the willows, but If you were to drop a fly into the pockets there are fish holding in the deeper areas.

There are large sections of prairie that are apparently free of any willows! Some areas contain willows on one side of the creek while the other sections are totally infested with willows. Unfortunately, the areas closest to the creek still have a major willow problem. 

Hay creek has 4 of the 5 Eros still producing deep enough water to hold trout. Only the #1 structure closest to the bridge is deep enough to hold nice sized fish. Two of the previous deep corners that held fish have filled in with sand and are devoid of fish. Pocket water does exist between the EROs but it lacks adequate depth or cover and seems to lack fish. Perhaps additional efforts such as adding a rocky substrate and additional structures could lead to more bank stabilization and subsequent undercuts that may attract trout. 

Cady creek, what a gem. While some areas still remain dominated by sand, many areas have flushed clean and provide pocket water up to 45 inches deep. From the snowmobile bridge upstream, the #1 ERO is still plagued by rock washed into the downstream side of the ERO. It won’t provide deep water until the rock is removed. We did remove the rock upstream last fall which allowed scouring to occur and the ERO went from 85% full to 50% full under normal water levels. With that said, there is deep water and trout in the bend due to natural snags and rock causing the water to rise over and cut deep water below the snags. The #2 ERO provided stable 4 feet deep water 55 feet downstream. That number has increased by 5 to 10 feet, but this might be temporary. The #3 ERO deep hole is HUGE! Over my waders and maybe over my head with an additional 10 feet of length of 3-foot-deep water added. In a previous report I stated, this is the strongest and best ERO ever built, but wow I was shocked. Too many spooked trout to count. 

I visited Halverson horse ranch to check on the scouring. It’s amazing and far better than after it was just finished. Enough said.

From my perspective the ERO’s constructed over the last 5 years have done a good job of creating deep runs.  These deep runs provide habitat and cover for mature fish and are an important component of a healthy fishery.

ERO Structures Number and Location:

Hay Creek, 5

Plum Creek, 2, uninspected this year

South Fork Kinni, 9  

Cady Creek, 3

Trimbelle Halverson easement, 2, uninspected this year

Trimbelle Thom easement, 1 or maybe 2, uninspected this year

Gilbert Creek in Dunn County, 10 or more and still being built

Loren Notes that the construction of ERO structures by the Wisconsin DNR is a “very good sign of things to come.”

Loren Haas 

May 8, 2023

Foam Wing No Hackle Mayfly

This is a specialty fly.  I wish I could tell you it works all the time. It simply doesn’t, however………

In the months from March to May, when the mornings are overcast, the blue wing olive mayflies are hatching, the fish are tail slapping the surface and you know they are taking emergers, then this is the fly you want. Don’t give up on your dry fly fishing just yet. This pattern will entice many of them to take an emerger and then grab your fly in the surface film. Tied in many colors and sizes I have chosen an early season dark BWO pattern in size 16 on a sprout hook.  Matching the size of the fly is more important than dialing in the perfect color.


I use heavy or standard hooks size 16 to 20 with olive thread. The under body on larger flies can be thin sticky back foam for more buoyancy covered with dubbing, smaller flies use only olive dubbing. The tail is horse hair or natural turkey biot short fibers. The magic wing material comes from the foam sheets that line the inside of mail envelopes and are found in colors grey, white, and clear. A thicker foam works better in the riffles.

  • Tie a dubbing bump at the bend of the hook. 
  • Splay the tail fibers over the bump, tie in and dub over the top. Add more dubbing to finish the body.
  • Cut a wing foam strip 1/8th inch by 2 inches and secure with a few figure 8’s, then cover with light dubbing.
  • Use one or more post turns to secure the open wing shape.  
  • Dub a small black head and superglue the thread one inch to whip finish.
  • Cut the wings to shape.

This is my go-to fly pattern for BWO hatches. It outperforms all others.