Understanding the Impacts of Culvert Performance on Stream Health Kristin Thomas Aquatic Ecologist Michigan Trout Unlimited Transportation and the Environment Conference 12/5/2018
Importance of adequately sized crossings Fish and organism passage Stream morphology Design considerations Funding and partnership opportunities
Why is connectivity important? Biologically Block passage of organisms Fish Invertebrates Amphibians Terrestrial Geomorphically Disrupts normal stream function Inhibits transport Sediment Wood Changes channel shape changes function
Culvert Problems Inlet or outlet drop (perch) Physical barriers Wood debris accumulation Excessive velocities Insufficient water depth Flow contraction (turbulence) Absence of bank edge areas Discontinuity of channel substrate Behavioral barriers Riparian fragmentations
How do culverts block AOP? Perched Velocity/turbulence Velocity
Swimming speed Burst Speed Highest speeds attainable Maintained only for short time <20 seconds Prolonged Speed Speeds fish can maintain for 20 seconds to 200 minutes Spans speeds between burst and sustained Often the speed used in culvert design Sustained Speeds fish can maintain for long periods of time >200 minutes
Why do aquatic organisms need to move? Spawning habitat Nursery habitat Foraging areas Deep water refuge Seasonal habitats Genetic variability Dennis Kirkland
Seasonal Movement Life stage movement needs Movement to meet a variety of needs Reproduction Colonization of available habitat Chemical or thermal refuge Food Can be daily, weekly, seasonally, yearly, or less Number Migrating 700 600 500 400 300 200 100 Migration Timing Design Window 300 250 200 150 100 50 Discharge (cfs) 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 0 Month Gullett, Kale. Aquatic Organism Passage. NRCS-ENTSC
Genetic Variability Genetic diversity correlated to population s ability to adapt Genetic diversity foundation of ecosystem diversity Sustainability of a population depends on the maintenance of genetic diversity Genetic drift and inbreeding depression Cannot maintain genetic diversity in small populations Must be able to move and interbreed with other populations
Not just fish!
Inter-specific Interactions Occurrence of some species depends on presence of others Freshwater Mussels Many species depend on fish hosts to complete lifecycle Larval mussels, glochidia, attach to fish gills to complete lifecycle Many will attach to any available fish Some are fish species specific
Snuffbox mussel Endangered mussel found in MI Need glochidia to attach to logperch, darters and sculpin Female attract logperch with soft mantle When the fish tries to eat the mussel grabs its head and shoots her glochidia into the fish s gills https://www.youtube.com/watch?v=- 1YcaIN8cRs
Riparian Wildlife Use river and streams as travel corridors Rivers and streams provide link connecting wetland, aquatic, and terrestrial ecosystems. Cross over road when no banks present in structure Dry passage opportunities reduce roadkill
Bankfull benches in large culverts
How do culverts disrupt stream function?
Geomorphic importance River can t flow efficiently through small culvert Disrupts sediment and organic material movement Upstream Slows velocity Build up of fine sediment Build up of wood and other debris Downstream Increase in velocity Scours deep pool Coarsening of substrate Increased erosive capacity
Geomorphic importance: Example Look at up and downstream characteristics to identify undersized crossings Stream width Substrate composition Bedform structure Compliment to visual data to indicate impact of culvert
Percent of Stream 100 90 80 70 60 50 40 30 20 10 0 Cedar River Example Bedform Composition Athey Rd. Upstream Just Above Just Below Downstream Pool Riffle Run Another undersized crossing Width (feet) Percent of Stream Bottom 35 30 25 20 15 10 5 0 100 90 80 70 60 50 40 30 20 10 0 Stream Width Around Athey Rd. Upstream Just Above Just Below Downstream Substrate Composition Athey Rd. Hard Fine Upstream Just Above Just Below Downstream
What are we after? Natural dynamic stream channel Passage of all aquatic organisms Low maintenance, flood-resilient road
Sizing and Placement of Stream Culverts Match culvert width to bankfull stream width Extend culvert length through side slope toe Set culvert slope same as stream slope Bury culvert 1/6 th bankfull stream width Offset multiple culverts Align culvert with stream Consider headcuts and cut-offs Dr. Sandy Verry, US Forest Service
MESBOAC Example
MESBOAC Example
MESBOAC Example
Stream Simulation Design Simulate the natural streambed Bed shape Particle diversity Roughness Mobility Forcing features Control permeability
Slide courtesy of Kozmo Bates, AquaKoz
Culvert Design Stream Simulation Slide courtesy of Kozmo Bates, AquaKoz
AOP and maintained stream function benefit aquatic organisms, streams, and humans 1. Less maintenance cost 2. Reduced overall long-term cost 3. Ecologically the right thing to do 4. Cooperative funding opportunities
Prioritization and Funding RSX inventory Identify crossing that are barriers Overlap of priority with partner groups Work together to fund optimal design
Funding Opportunities USFWS Fish Passage Program DNR Aquatic Habitat Grant Program Sustain our Great Lakes
Contact Information Kristin Thomas Michigan Trout Unlimited 616-460-0477 kthomas@michigantu.org