Intersects of Transportation and Aquatic Systems: the Economic and Ecological Cost in Idaho

Focus Area

Wildlife & Ecosystems


Natural Resources







Research Idea Scope

Idaho’s topography requires that its roads and highways system cross a large number of waters.  Each of these crossings represents not only a design challenge in terms of road and highway construction and maintenance but each has the potential to either limit or provide for fish passage up and down the water being crossed.    Highway design and construction in the past was focused on the minimum requirements necessary to maintain the integrity of the road in relation to water crossing hydrology.  However, in most cases these designs focused on passing high water volumes during spring runoff.  As a result, many culverts and fills limit or block fish passage during all but high water periods and may block fish passage even during high water due to water velocities.   Identifying and removing such barriers could greatly increase fish populations and habitat, benefitting anglers and priority conservation species such as salmon and steelhead and bull trout.   This project will inventory and prioritize fish barriers related to state and county roads in Idaho and quantify the work in terms of highway construction impact and restoration cost and benefit in terms of fish habitats and populations.  The project will be completed using the following steps: 1) Develop a map of all state and county roads that intercept perennial streams and classify each in terms of type of water crossing.  2) Prioritize road/stream intercepts based on water crossing type and number and type of fish species, and stream order.  3) Ground truth, classify, and photograph each stream crossing, in order of priority and according to standardized and accepted protocols.  4) Describe each fish barrier and its potential design fix according to standardized and accepted protocols.  5) Describe potential fish benefits to barrier removal in habitat and population terms through use of existing instream survey and habitat databases upstream of barrier.   6) Populate a MS Access database with all ground truth, classification, and Idaho Transportation Department and county road district information, and habitat and fish population information related to each identified barrier.  7)  Develop, implement, and display a web-based tool using Google Earth to provide completed fish barrier inventory including all data and metadata associated with each barrier.  8) Assess and report on highway impacts and cost and benefits of restoration in economic, biological, and ecological terms.  The project will be completed in cooperation with interested transportation, Tribal, local government, and public land partners and the data and reports will be made available on the Department web page.  Potential cost share and match funding will be explored.

Urgency and Payoff

Objective evaluation of aquatic and fisheries barriers related to transportation systems in Idaho. Identified action list for restoration of aquatic ecosystem linkage in relation to conservation priority. Measures of aquatic ecosystem restoration actions in habitat and fish population parameters. Cooperative project involving transportation system and wildlife managers. Standardized and objective measure of transportation modifications in relation to conservation parameters and priority at a statewide level.

Suggested By

Gregg Servheen, Idaho Dept of Fish and Game