Trained Lead Observers certified to assess tidal stream crossings use a uniform protocol throughout the thirteen state, North Atlantic region. 

This protocol includes observations of the crossing (for example road type, flow condition, crossing alignment) and of the structure itself (for example material, shape, dimensions).

The Tidal Stream Crossing Instruction Manual for Aquatic Passability Assessments explains this survey protocol for use with either paper field data forms or an electronic version of the forms - the offline data manager (ODM) - that can be used with smart phones, tablets and laptop computers. The field data form and instruction manual for this protocol are available under NAACC Documents.

The NAACC has finalized two scoring systems to help interpret data collected from stream crossing assessments:

• A classification scoring approach, where each crossing is assigned to a category based on the degree of aquatic organism passage (AOP) through the structure. These fairly broad categories include: Good AOP, Moderate AOP, Poor AOP, and No AOP.
• A numerical scoring approach, where mathematical formulas using the data from the assessment are used to compute a numeric score for each crossing. Scores range from 0 (no aquatic organism passage) to 1 (full aquatic organism passage).

Upon entry into the database, all crossings are automatically scored using both scoring systems. In the mapping interface we currently show only the numeric passability score and associated descriptors. We are planning to implement changes in the map viewer that will allow users to choose whether to display the numeric score descriptors or the AOP classification

A description of both scoring approaches can be found under NAACC Documents.

The NAACC has completed a HUC12 subwatershed prioritization to help identify subwatersheds that may be higher priority for field survey.

The prioritization included criteria such as diadromous fish, brook trout, likelihood of crossing failure, greater uncertainty of crossing passability, and impact of crossing failure.

The results of the prioritization, which may be viewed for the entire NAACC region or stratified by state, are displayed on a web map (click here) and can be explored through use of a customizable tool (download here) for use with ArcGIS Desktop.

You can learn how to use the web map and custom tool in our Prioritization for Field Inventory webinar:

• Presentation Documents
• Webinar Recording

Please contact Erik Martin with any questions about this prioritization.