Tens of thousands of culverts are past their retirement age and were typically hydraulically designed for the hydrology of the mid-twentieth century. Detailed study of each and every culvert will be time consuming, however at the same time, many states have embarked on asset management strategies that take rudimentary field information at each culvert in order to define these assets. These field data provided the input to a code to perform hydrologic, hydraulic, and aquatic organism passage (AOP) characteristics. The code was written into an EXCEL spreadsheet that accommodates either user input or input from a GIS database. The code can also provide assessments in a batch mode (multiple culverts at once).

Code input includes the culvert geometric data and latitude/longitude coordinates. The coordinates locate the watershed and thereby all watershed characteristics may be found in GIS databases (land use, hydrologic soil group, runoff travel paths, watershed slope, etc.). Runoff computations are performed either by the NRCS method for watershed areas less than 2 mi2 or USGS regression equations for larger watersheds.

As a test of the code, a current project funded by NOAA and NHDES studied 105 culverts selected by ten seacoast New Hampshire towns. These culverts were identified by the towns as "problem" culverts: often meaning undercapacity. Watershed areas to each culvert were generally less than 3 sq. mi. These culverts were modeled with the FHWA HY8 code as well as the EXCEL code. The comparisons were extremely similar, as both codes are based on the same fundamental equations. Hydraulic analyses built into the code include 10-, 25-, 50-, and 100-year floods. AOP assessment employs the Vermont protocols.

Some of the more interesting results include: the majority of culverts are under outlet control, only 9% provide full AOP, yet 2/3 provide reduced AOP.

Thomas P. Ballestero, University of New Hampshire. Tom is a hydrologist and water resources engineer with four decades of national and international experience in stream systems, stormwater management, and groundwater hydrology. He is a licensed Professional Engineer, Professional Hydrologist, and Professional Geologist. Areas of expertise include: stream restoration, stormwater management, stream crossings, fish passage, geomorphic assessments, dam removal, hydrology, hydraulics, sediment transport, and coastal engineering. Aside from teaching undergraduate and graduate courses he performs all aspects of projects including field data collection, project management, design, alternatives analysis, data analysis, public outreach, construction supervision, permitting, and monitoring. Tom was a lead author for the technical aspects of the Stream Crossing Guidelines for the State of New Hampshire. Tom is a member of the Scientific Resolution Panel to arbitrate technical disagreements between communities and FEMA regarding riverine, lacustrine, or coastal flood insurance studies.