We have developed a protocol for the assessment of road-stream crossings for passability by terrestrial wildlife. The protocol includes data forms, instructions, and a document describing the scoring system for terrestrial passability, all available on our NAACC Documents page. An online database was created to serve as a convenient repository of the data collected during crossings surveys.
Anyone can survey crossings using NAACC protocols but they must belong to an organized regional group headed by a designated survey coordinator. Training and certification are also required, to ensure high quality data. We are currently developing an online training and certification module that should be available later this summer. Once the training and certification module has been implemented, lead observers will be able to take the training and, upon certification, be able to contribute data to the NAACC terrestrial passability database.
Assessment Protocol
Trained Lead Observers certified to assess stream crossings use uniform assessment protocols throughout the thirteen-state, North Atlantic region. The certification system for terrestrial passability assessments is coming soon.
Terrestrial passability assessments include observations and measurements of the entire crossing (for example road type, flow condition, crossing alignment) and of one or more structures (e.g. culverts) that make up the crossing (for example material, shape, dimensions). The NAACC Terrestrial Stream Crossing Survey Instruction Guide 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.
Scoring for Passability
The NAACC has finalized a scoring system to help interpret data collected from terrestrial stream crossing assessments. A numerical scoring approach uses mathematical formulas applied to data from assessments to compute a numeric score for each crossing. Scores range from 0 (the worst crossing from a connectivity perspective) to 1 (a perfect crossing from a connectivity perspective) for six groups of animals that might potentially use road-stream crossings.
Upon entry into the database, all crossings are automatically scored for each animal group, as well as an overall score for wildlife passability. In the mapping interface we currently show only the numeric passability score and associated descriptors for aquatic passability at non-tidal crossings. We are planning to implement changes in the map viewer that will allow users to choose to display scores for any of the NAACC crossing assessment protocols.
A description of the scoring approach can be found under NAACC Documents.