Projects on the water present unique challenges to professional engineers, scientists, planners, and contractors. Thew Associates has extensive experience working in marine environments providing seamless topographic and utility mapping from upland surveys through transition zones and into deeper water.

Thew Associates specializes in working in near-shore and inland water environments. Our shallow draft and unmanned surface vessels allow us to navigate in shallow waters, and our staff is experienced with wading in the near shore areas and marshes to collect the requisite bathymetric data.

Thew Associates is fully equipped to undertake a wide range of water projects utilizing various technologies including single and multi-beam bathymetric surveying and mapping, backscatter data, sub bottom profiling, marine magnetometer surveys, Acoustic Doppler Current Profiling (ADCP), and sediment sampling and analysis.

GPS Positioning

  • Centimeter horizontal and vertical accuracies
  • Sample layout and location
  • Sampling vessel navigation

Sediment Sampling and Analysis

  • Vibracore and gravity core sample collection
  • Sub-bottom profiling
  • Chemical and geotechnical analysis (subcontracted)

Backscatter Data

  • Side Scan Sonar and Snippets
  • Seafloor imagery and classification
  • Object detection
  • Full Water Column

Sub Bottom Profiling

  • Identify and characterize seafloor strata
  • Buried object detection
  • Benthic habitat characterization

Marine Magnetometer Surveys

  • Magnetic object detection
  • Identifies submerged cables and pipelines
  • Archeological features

Acoustic Doppler Current Profiling (ADCP)

  • Velocity and Current Studies
  • Construction and remediation design data
  • Flow rate and direction determination
  • Hydraulic modeling support
  • Wave Height Studies And Monitoring


  • Single- and multi-beam acoustic data collection
  • Slope monitoring
  • Dredge support services
    • Pre- and post-dredge surface topography
    • As-built surface topography
    • Dredge volume calculations
Hydrographic surveying

Subbottom Profiling

Hydrographic surveying

Acoustic Doppler Current Profiling

hydrographic surveying


hydrographic surveying

Sediment Sampling

Hydrographic surveying

Magnetometer Survey

Hydrographic surveying



Land Surveying

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Hydrographic Surveying

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Subsurface Utility Engineering

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Laser Scanning

3D Laser Scanning Services

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Drone Services

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6431 US Hwy 11
Canton, NY 13617

Phone: 315-386-2776 
Fax: 315-386-1012


9478 River Road
Marcy, NY 13403

Phone: 315-733-7278
Fax: 315-797-1957

Tupper Lake

29 Park Street Suite 3
Tupper Lake, NY 12986

Phone: 315-267-6007


5866 State Route 31 
Cicero, NY 13039

Phone: 315-244-2151

Thew Associates Land Surveyors
Site Design by Coughlin