January 26, 2023 at 12:45 p.m.
Oneida County completes Great Lakes Stream Crossing Inventory
Oneida County completes Great Lakes Stream Crossing Inventory
With the special project concluded, the department now has a better picture of the condition of culverts in all 20 towns within the county. According to county conservationist Michele Sadauskas, the county was able to secure a grant allowing JoAnne Lund to complete the field work necessary to gather all of the data.
In 2020, 105 culverts were analyzed in the towns of Hazelhurst, Lake Tomahawk, Little Rice, Lynne, Minocqua and Woodruff. In 2021, in the towns of Crescent, Enterprise, Monico, Pelican, Piehl and Schoepke, 90 culverts were inspected, and this past field season, Lund was able to inspect 113 culverts in Cassian, Newbold, Nokomis, Pine Lake, Stella, Sugar Camp, Three Lakes and Woodboro.
Lund recently shared her findings via Zoom presentation. She spoke about the survey components, or things she looked at for each site. She first took photographs of each site, both upstream and downstream, then performed a variety of measurements. Those measurements included stream flow velocity, water depth, bank and roadway slope, structural measurements and condition assessments, depth of each structure and visible erosion at each site. Culverts should also be wide enough to cover at least half the bank full width of the stream.
Passability
One of the conditions on which stream crossings at culverts were rated was on passability. Passability refers to whether or not fish and other aquatic species can move through the culvert in both directions during different stages of their life cycle. In order to be deemed passable, a culvert needed to be more than six inches in depth and have a water velocity of under three feet per second. There should also be natural substrate or sediment present in the culvert, she said. Structures should be placed below the stream.
Structural Condition
Lund also looked at the structural condition of the culvert itself. She looked to see whether the structure looked new or had no deficiencies. A structure considered to be in the "good condition" category had only superficial corrosion. Those in the moderate category showed moderate deterioration from corrosion or abrasion. Major deterioration from corrosion or abrasion between 5-10%, landed culverts in the next category of impairment.
Those with deterioration from 10-50% were given the "major deterioration" designation. Those with more than 50% corrosion or abrasion were listed as being seriously deteriorated.
When looking at structural condition, only 9 sites were found to have no deficiencies. However, 22 were listed as either in new condition or good condition. Thirty-seven landed in the moderate deterioration category. Nine were categorized to have major deterioration, and 11 were severely deteriorated. The rest fell into the moderate to major category.
Erosion
Erosion at culvert sites can be an issue in many respects. It can impact fish feeding, fill in spawning areas, smother aquatic plants, decrease oxygen levels and increase water temperature.
Lund was also charged with determining and quantifying the amount of erosion at each culvert site. She did this by using the U.S. Department of Agriculture Natural Resources Conservation Service's (NRCS) Universal Soil Loss Equation (USLE).
Results
When looking at the 113 sites from this year's field work altogether, almost one-quarter (24.8%) of culverts studied in 2022 were a 100% barrier for passability. This meant that most fish and aquatic life could no longer utilize that crossing to move from one place to another. That amounted to 28 culverts. Only 15% of those surveyed were not a barrier at all. The same number, 15%, were found to be a barrier at most flow levels and 33.6% to be a barrier at high flow levels only.
Lund also spoke about issues on a town-by-town basis.
In the Town of Cassian, she said, she inspected 12 crossings. Of those, 33% were a barrier to passability 100% of the time. Twenty-five percent were not a barrier at all.
Fourteen sites in the Town of Newbold were inspected this year. Lund found 14% of those to not be a barrier at all, but 35.7% to be a 100% barrier. Of those culverts, she said, three should be assessed in the near future.
In the Town of Nokomis, Lund said, 12 sites were inspected. One-quarter of those sites were found to be a barrier to fish passage at all times. Sixteen percent posed no barrier at this time. Four of those sites she listed as being in need of assessment soon.
In the Town of Pine Lake, Lund monitored 11 sites. Of those 18% were found to not be a barrier, while 27.3% were found to be a barrier 100% of the time. While there were four sites listed in the moderate to major category as far as structural condition, she said, none were in a state of needing immediate action.
The Town of Stella has 15 sites inspected by Lund. Twenty percent of those provided no barrier to aquatic life movement at all, while the same percentage served as a barrier 100% of the time. Only two sites, she said, were in need of immediate attention. In one instance, the roadway had to be closed due to a failed culvert. Her recommendation was to repair or replace the other soon.
Of the 21 sites in Sugar Camp, only 4.76% (one) was found to not be a barrier to fish passage at any time. Just over 19% were a barrier 100% of the time. Lund also found two major deficiencies and three major deterioration sites in the town.
In the Town of Three Lakes, Lund found 15.8% of the 19 sites to be a barrier to passage for aquatic life 100% of the time. Twenty-one percent were not a barrier at all. Overall, she said, the town's culverts were in good condition, but there were two sites with major deterioration.
Nine sites in the Town of Woodboro were evaluated as well. Of those, only one was found to not be a barrier at all while 33% were found to be a barrier 100% of the time. Two sites, Lund said, showed major deterioration and should be repaired or replaced.
Lund provided a listing of sites that were deemed to be priority sites based on passability, structural condition or erosion. Twenty-eight sites were deemed priority based on passability. Forty-three were deemed priority based on structural condition and 13 based on erosion issues associated with the culvert. Lund provided a list of those stream crossings.
The final report will be available on the Land and Water Conservation Department website, oclw.org, as well as each individual town's report, Lund noted. Sadauskas said the county would look to share those reports with the towns and to provide any assistance towns may need to look for grant funding or other available means to rectify some of the issues with some of the culverts in the county.
Beckie Gaskill may be reached via email at [email protected].
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