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Category: Senior Biologists

Avery Scherer, Ph.D.

Senior Ecologist

B.S. Aquatic Biology; Ph.D. Marine Ecology

Phone: (888) 224-1221

 

West Sacramento, California

Avery is an aquatic ecologist with 10 years of experience working in diverse ecosystems, from streams in eastern Kentucky and Hawaii to oyster and coral reefs in south Texas and the Caribbean. Her research interests include predator prey relationships, trophic cascades, and the influence of species interactions on ecosystem structure and function. She is also interested in science communication and outreach; she has experience in informal science education programs as well as with science writing and social media. As an ecologist at CFS, Avery helps to design and conduct research on the role of stream ecology in the efficacy of river restoration for salmon and steelhead.

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Johnny Caspers, P.E., M.S.

Restoration Engineer

M.S. Environmental Engineering

Phone: (888) 224-1221

 

West Sacramento, California

Johnny is a restoration engineer with a background in environmental remediation, water resources, and habitat restoration. His experience includes aquatic habitat restoration design, hydrologic and hydraulic modeling, groundwater recharge design, topographic data collection, and construction monitoring. Through this work he has developed a fundamental understanding of surface water and groundwater interaction, restoration design, and project implementation across a variety of scales. Additionally, Johnny is proficient in a wide variety of computer-based tools including AutoCAD Civil 3D, ArcGIS, HEC-RAS, HEC-HMS, XPStorm, and MODFLOW. These skills along with his experience conducting topographic surveys and measuring discharge with Acoustic Doppler Velocimeters and Acoustic Doppler Current Profilers underscore Johnny’s ability to serve in a variety of technical roles. This technical basis and a diverse background allows Johnny to perform a wide variety of tasks at a high level, while bringing a holistic approach to restoration design.

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Ryan Flaherty, M.S.

Senior Biologist
B.A. Ecology; M.S. Marine Resource Management

Phone: (503) 850-9610

 

Portland, Oregon 

Ryan is an exceptional fisheries biologist with over a decade of experience conducting and leading a variety of sampling and monitoring projects. Ryan has extensive field experience that includes deployment and operation of biotelemetry equipment, collection of juvenile outmigrant data (rotary screw and incline plane traps, PIT tagging, snorkeling), water quality sampling, boat operations, and assessment of aquatic and riparian habitats. Prior to joining Cramer Fish Sciences, Ryan worked on studies evaluating survival rates of juvenile salmonid passage through hydroelectric projects and estimating the exposure of ESA-listed salmonids to harmful levels of total dissolved gas. As a graduate student, Ryan researched how genetics-based tools can be used to identify catch distributions for Chinook salmon at refined space-time scales that are beyond the capacity of traditionally reported coded-wire tag data. Ryan is well versed in managing and analyzing complex data sets in R and GIS, developing web-based applications to host and visualize data, and preparing and editing technical reports and publications.  

Selected Publications

 

Arntzen, E. V., R. J. Flaherty, A. H. Colotelo, R. D. Harnish, J. Vavrinec, S. A. Zimmerman, J. D. Tagestad, and K. Stertz. 2018. Assessment of the effects of total dissolved gas exposure of upper Willamette River Chinook salmon and steelhead below Foster Dam. PNNL-27325. Final report prepared for the U.S. Army Corps of Engineers, Portland District, Portland, Oregon, by the Pacific Northwest National Laboratory, Richland, Washington.

 

Liss, S. A., J. S. Hughes, E. F. Fischer, R. J. Flaherty, and J. P. Duncan. 2017. Willamette Valley high head bypass downstream passage prototype evaluation: radio telemetry evaluation of the connecting and bypass pipes at Green Peter Dam, 2016. PNNL-26198. Final report prepared for the U.S. Army Corps of Engineers, Portland District, Portland, Oregon, by the Pacific Northwest National Laboratory, Richland, Washington.

 

Hughes, J. S., S. A. Liss, R. J. Flaherty, E. S. Fischer, B. J. Bellgraph, C. V. Vernon, and G. E. Johnson. 2017. Evaluation of juvenile salmonid passage and behavior at Foster Dam using radio telemetry, 2016. PNNL-26416. Final report prepared for the U.S. Army Corps of Engineers, Portland, Oregon, Portland, Oregon, by the Pacific Northwest National Laboratory, Richland, Washington.

 

Flaherty, R. J. 2015. Tags versus genetics: identifying which tool provides the best information about Chinook salmon (Oncorhynchus tshawytscha) distributions in the California Current. M.S. Thesis, Oregon State University, Corvallis.

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Tyler Rockhill, P.E., M.S.

Restoration Engineer II

B.S. Civil/Environmental Engineering, M.S. Hydrology

Phone: (888) 224-1221


Boise, Idaho

Tyler is a Restoration Engineer with extensive experience in water resources and hydraulic engineering in the Pacific Northwest. His experience includes aquatic habitat restoration design, hydraulic and hydrologic modeling, sediment modeling, large wood design, floodplain mapping, geomorphic and habitat assessment, and hydrometric surveying. Tyler’s diverse background includes experience at every step of a project from prioritization and planning to site assessment, literature review, data collection and surveying, modeling and design, permitting, and construction. This experience allows for an interdisciplinary, process-based understanding of project delivery. He has experience developing hydrologic and hydraulic models such as HEC-RAS, SRH-2D, River2D, HEC-HMS, HPSF, MGSFlood, HY-8, SWAT, WMS, SWMM, and StormShed.  He is an experienced jet boat and raft operator in lakes, rivers, and deltas, including for the purposes of topobathymetric and hydrometric surveys. Tyler has experience working on a broad range of river engineering projects such as culvert replacements, hydraulic and hydrologic modeling, floodplain mapping, and bank erosion/scour protection.

Selected Publications

 

Collins, V. and T. Rockhill. 2021. Oso Landslide Memorial Site Hydraulic Analysis, Northwest Hydraulic Consultants Inc, prepared for Snohomish County Parks and Recreation.

 

Collins, V., Payne, J., Rockhill, T., Nelson, A., Dufficy, A., and M. Ohrt. 2021. Abbott Levee Habitat Improvement Project: 100% Basis of Design Report, Northwest Hydraulic Consultants Inc, prepared for Whatcom County Flood Control Zone District.

 

Collins, T., Brown, J. and T. Rockhill. 2021. Ferndale Levee Improvement Project Hydrology, Hydraulics, and Geomorphology Existing Conditions Report, Northwest Hydraulic Consultants Inc, prepared for Whatcom County Flood Control Zone District.

 

Dillon, P., Brooks, P. and T. Rockhill. 2020. Avondale Road Erosion Existing Hydrologic and Hydraulic Conditions, Northwest Hydraulic Consultants Inc, prepared for City of Redmond.

 

Collins, V., Leytham, M. and T. Rockhill. 2020. Coweeman River Levee Raise Hydrograph Development Memorandum, Northwest Hydraulic Consultants Inc, prepared for Shannon & Wilson.

 

Bennett, T., Rockhill, T., and D. Jones. 2020. Maddox Creek/Big Ditch Alternatives Evaluation, Northwest Hydraulic Consultants Inc, prepared for Skagit County Drainage and Irrigation District #17

 

Washington State Department of Transportation. 2018. SR 529 Steamboat Slough Mitigation Site.

 

U.S. Army Corps of Engineers. 2017. Wyoming Stream Quantification Tool (WSQT) User Manual and Spreadsheet. Beta Version.

 

Meixner, T., Papuga S.A., Luketich, A.M., Rockhill, T., Gallo, E.L., Anderson, J., Salgado, L. Pope, K. Gupta, N., Korgaonkar, Y., Guertin, D.P. 2017. Green Infrastructure Increases Biogeochemical Responsiveness, Vegetation Growth and Decreases Runoff in a Semi-Arid City, Tucson, AZ, USA.  American Geophysical Union, Fall Meeting 2017, abstract #H34H-06.

 

Tyler Rockhill.  2017. Influence of Soil Physical and Chemical Properties on Soil CO2 Efflux in Semi-Arid Green Stormwater Infrastructure.  Department of Hydrology and Atmospheric Sciences. University of Arizona. Master’s Thesis.

 

Chatel, J., and Vouno, S., 2012 Sawtooth Bull Trout Management Indicator Species Monitoring Report, United States Forest Service

 

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