Ashland NFWCO has completed its largest fish passage project to date, restoration on 18 Mile Creek in the Town on Grandview, Bayfield County, WI.  18 Mile Creek is well known for its naturalized brown trout and brook trout fishery. The creek meanders through central Bayfield County before joining the Long Lake Branch of the White River in the Bibon Swamp, a designated state natural area. 

The crossing on North Sweden Road was perched at approximately 12” and was a velocity barrier for most life stages of fish in 18 Mile Creek.  Over 16 miles of additional spawning and rearing habitat was blocked by this perched culvert.  Additionally, the 12’ x 65’ culvert was failing structurally and was not long enough to allow adequate slope coverage on the ends of the culvert and was causing erosion to occur on the road edges.

Ashland NFWCO met with town officials, Bayfield County Land Conservation Department (BCLCD) and Wisconsin Department of Natural Resources (WDNR) Fishery Biologist Scott Toshner to discuss the replacement of the culvert.  After completing the pre-construction survey for the hydraulics of the system, the BCLCD, with assistance from the Natural Resources Conservation Service (NRCS) designed the engineering plan.  It was decided to replace the old pipe with a 12’ x 80’ culvert, thus allowing for a slope gradient of 2:1 for the road bed. 

The Town of Grandview contracted with K & D Excavating of Ashland, WI, for assistance with the replacement of the culvert.  Construction started on September 10 and was completed on September 12.  Approximately 6’ of road-fill needed to be removed to uncover the old culvert.  Along with the road bed covering the culvert K & D dug a by-pass channel to divert the creek through, as the flow is too large to be handled by diversion pumps.  It took two large excavators to remove the old culvert, along with a D-8 bulldozer. 

Once the old culvert was removed, ground elevations were taken to set the new culvert at the needed elevation.  This is where the crew ran into a problem, as the old culvert was set on a old cement bridge foundation that no one knew was there.  It took a afternoon to break this old abutment up and remove these concrete chunks.  After the proper elevation was obtained, it then took the three pieces of equipment to lower the two 12’ x 40’ sections into place.  These were then banded together and the process of filling and compacting around the culvert was begun. 

Once the culvert had approximately a foot of fill over it the diversion channel was slowly opened and allowed to flow into the new culvert.  The stream bed immediately began filling the bottom of the culvert and within 24 hours had head cut upstream approximately 75 meters and deposited 12 – 14” of fill in the culvert.  Both ends of the culvert were armored with large boulders and rock to prevent erosion and the area was seeded and mulched.

To assess whether this project would be successful the Ashland NFWCO conducted a pre- and post- construction fishery survey.  In discussions with the WDNR it was suggested to survey the area above the culvert and mark all fish caught upstream.  All trout caught above 150 mm (6”) were kept and moved down below the existing perched culvert.  It was felt that these fish wouldn’t be able to pass through the old structure and would only be able to migrate upstream once the culvert was replaced.  A crew went out on August  30 and caught a total of 172 trout by electrofishing.  Of these, 168 were brown trout and the other four were brookies; 57 were large enough to move below the culvert. 

On October 11, after a good rain event finally occurred in the area, Ashland NFWCO, along with assistance from the Fishery Management class from Northland College, Ashland, WI, did the recapture run, netting 113 trout, eight brookies and 105 brown trout.  No brookies were recaptured, but a total of 26 brown were recaptured, for a 35 percent recapture rate. 

Everyone involved with the project was happy with the results.  Ashland NFWCO is currently creating a video showing all aspects of the culvert replacement and fishery survey.  This video will be available to all interested parties by contacting Ashland NFWCO and requesting a copy.