Northern Research Station News Releases

Research Delivers Tool for Anticipating Effects, Benefits of River Restoration

Los Angeles River by the Bowtie Parcel Park. Photo by Yassy Wilkins, USDA Forest Service - State & Private Forestry, Los Angeles Urban Center for Urban Natural Resources Sustainability Madison, WI, April 14, 2020 - Research by a USDA Forest Service scientist and his partners delivers data urban engineers and planners can use to more holistically address an invisible but pervasive form of river pollution. Thermal pollution occurs as rivers move through channels without riparian vegetation and its protective shade, channels disconnected from cool groundwater inflows due to concrete lining, and channels receiving warm stormwater runoff from the urban heat island infrastructure such as parking lots and roads.

New research combined two approaches to river modeling, the U.S. Army Corp of Engineers’ Hydrologic Engineering Center River Analysis Software, the gold standard for hydrological modeling, and the i-Tree Cool River model to simulate the shading effects riparian trees and cool groundwater inflows from terrestrial and aquatic green infrastructure. The i-Tree Cool River model was developed by USDA research partners Reza Abdi and Theodore Endreny at SUNY College of Environmental Science and Forestry (ESF), and is part of i-Tree, a state-of-the-art, peer-reviewed software suite from the USDA Forest Service that delivers online urban and rural forestry analysis and benefits assessment tools. These tools simulate how trees reduce pollution, including air pollutants, stormwater pollution, air thermal pollution, and now river thermal pollution.

Senior Scientist Dave Nowak of the Forest Service’s Northern Research Station joined Abdi and Endreny in applying the i-Tree Cool River model to two watersheds, one a small forested mountainous watershed in New York and the other a large highly urbanized Los Angeles River watershed characterized by concrete, straight lines and lack of vegetation. Their objective was to demonstrate how riparian forests, green infrastructure, and removal of concrete can help promote river thermal restoration, suitable habitat for native fish species, and does not disturb flood management.

The Los Angeles River has been targeted by the U.S. Army Corps of Engineers for ecological restoration, and the i-Tree Cool River model can assist with the restoration of cooler river temperatures.

“River restoration requires a significant investment, and this research allows land managers and planners to quantify the outcomes of proposed restoration actions and it establishes that i-Tree Cool River can augment the existing Hydrologic Engineering Center River Analysis Software modelling,” Nowak said.

Abdi and Endreny say the inspiration for i-Tree Cool River model was their childhood joy of cool swimming and fishing holes in rivers with healthy forest canopy cover, and the desire to restore river water temperature and quality so that joy is available for future generations.

The study, “A model to integrate urban river thermal cooling in river restoration,” was recently published in the Journal of Environmental Management and is available through the Northern Research Station at:


The mission of the Northern Research Station is to improve people's lives and help sustain the natural resources in the Northeast and Midwest through leading-edge science and effective information delivery.


The mission of the U.S. Forest Service, an agency of the U.S. Department of Agriculture, is to sustain the health, diversity and productivity of the nation's forests and grasslands to meet the needs of present and future generations. The agency manages 193 million acres of public land, provides assistance to state and private landowners, and maintains world-renowned forestry research and wildland fire management organizations. National forests and grasslands contribute more than $30 billion to the American economy annually and support nearly 360,000 jobs. These lands also provide 30 percent of the nation's surface drinking water to cities and rural communities; approximately 60 million Americans rely on drinking water that originated from the National Forest System.


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Last modified: April 14, 2020