Assessing wildfire risk to municipal drinking water sources

Assessing wildfire risk to municipal drinking water sources

Status

Completed

Start Date

May, 2021

Remains of a drinking fountain after the 2020 Riverside Fire in the Mount Hood National Forest.

Wildfire management has important long- and short-term implications for landscape structure, in-stream habitat conditions, and water quality. The risks of habitat degradation for native fishes and water quality, particularly for municipal watersheds, vary across the watersheds of western Oregon and Washington. This project addresses questions of interest for management of municipal watersheds in light of modeled water quality impacts from predicted wildfire.

This study is part of the West-Side Fire and Climate Adaptation Research Initiative convened by the PNW Research Station in 2019.

Overview
Research
People
Resources

Project Description

Erosion model: Researchers are developing geospatial datasets (using NetMap and LIDAR) that characterize sediment delivery to streams through erosion, landslides, debris flows, and flash floods.

Much of the population in western Oregon and Washington relies on forested watersheds for drinking water and other municipal uses. Rivers and streams in the region are also home to several species of imperiled salmon. Although most source watersheds have not burned in well over 100 years, wildfire risk assessments and recent high-severity wildfires are a reminder to local water providers and forest managers that wildfire is an unavoidable threat to municipal water supplies that can create lasting negative impacts to water quality and quantity.

We will develop geospatial datasets that characterize sediment delivery to streams through erosion, landslides, debris flows, and flash floods. Action-ready science products will be developed with municipal water providers, collaborative groups, and local governments to help identify areas that are particularly vulnerable to wildfire impacts on water quality and to guide pre- and post-wildfire management strategies to protect drinking water and fish populations.

Purpose and Scope

Information developed by this project will help decisionmakers identify the type of pre- and post-wildfire management actions to take, where to take those actions, and the anticipated outcomes of the management.

Methods

We will develop erosion predictions from digital elevation models using LiDAR. The targeted model datasets we will be developing include:

Surface erosion/sediment delivery to stream
Gully erosion
Shallow landslide potential/delivery
Channelized debris flow potential/delivery
Flash flood potential
Wildfire predicted burn intensity

Modeled datasets will be mapped and ESRI storymaps created to contextualize data models and identify places to target for prefire planning, and in postfire stabilization work.