A River’s Watershed

Mark Hanna is a civil engineer with a specialization in water resources management and river restoration and revitalization. His passion for rivers has led him to work extensively on a variety of projects up and down the LA River. 

“I prefer projects that are right here in Los Angeles. I live here, my family lives here. So I’d rather put my efforts, my sweat, blood, and tears into something that’s going to make where I live a better place.”

His recent work on the LA River Master Plan has been a highlight of his career. The 2022 Master Plan addresses a wide range of social and environmental issues facing the LA River through a data-driven approach and proposes the river as a connector, as close to one million people live within a one-mile distance of the river. Throughout its 51-mile route, the river passes through 17 municipalities and numerous communities, and through 2,300 acres of public land. In a city and county where space is at a premium, this public land presents a tremendous opportunity to reactivate the river while addressing key issues the county is facing: flood risk reduction, lack of affordable housing and green spaces, issues of water quality and control, and much more. 

Working on the Master Plan was a critical moment for Mark, it cemented an understanding that he developed over the course of his career: the river is the result of its watershed and carries with it not just water but all the societal issues that surround it. 

“The LA River carries rainfall runoff during the wet season and brings it down to the Pacific Ocean. Every single day, when it’s not raining, it’s still carrying water out to the ocean. A significant portion of that dry-weather flow is made up of discharges from the three water reclamation plants.

We as a region have trouble supplying our demands locally, so we have aqueducts that bring water from the Colorado River and from the Eastern Sierras. It comes right to our tap, and all of that goes out to the drain to one of these water reclamation plants. 

That water is released again, flows down the [LA] river 365 days a year, and empties into the ocean. That [water] grows a lot of vegetation. We, as people, like to have a lot of vegetation, but it is actually growing a lot of non-native vegetation as well.” 

In the Glendale Narrows, it is this vegetation that attracts both animals and humans to the river. This vegetation and constant stream of water beautifies the river, but inadvertently increases flood risks, as this vegetation slows down the waterflow during storm events and can lead to water levels rising over the river channel. 

“Being in nature, that’s my church. You could put [the river] in concrete and you could say it’s a channel, but it is the natural world. People are going to have that draw to it that is going to keep coming; that force is very strong.

Here in Los Angeles, people want so much out of the river channel, people want so much for their communities, rightfully so, and my contribution to that effort is a small piece.”

Mark Hanna is a Senior Principal Water Resources Engineer based in Southern California with more than 25 years of experience focused on water and natural resources. He specializes in river basin management and planning, local water supply reliability, large system hydrology and hydraulics, surface water and groundwater management, and waterfront resilience.