Working to
Restore Rivers
Since 1984

Featured Projects

2022-04-21T22:08:37+00:00

Dam Removal & Fish Passage

Fish passage barriers across the United States are being removed or modified to help fish and wildlife, improve safety and boost recreation. We’ve worked on 130+ dam removals, removed hundreds of culverts, and developed best practices resources for bridge crossings.

2022-09-15T16:55:48+00:00

Estuary Restoration

Estuaries are dynamic ecosystems where oceans, rivers and human economies converge; they’re also critical to rearing grounds for fish and wildlife and at particular risk to a changing climate. Across the country, we’re reconnecting and restoring these habitats.

2022-05-25T15:25:01+00:00

Urban

Beginning with the daylighting of Tanner Creek in Portland (1992), we’ve been collaborating with urban planners and landscape architects to restore urban streams from coast to coast in the US and abroad.

Thanks to Sonoma Water for sharing this video highlighting more than a decade of working with private landowners and resource agencies in the Dry Creek valley to restore habitat for endangered Coho and Steelhead. To date three miles of Dry Creek have been restored by Sonoma Water with another 3 miles to be constructed in close collaboration with The Army Corps of Engineers.

Inter-Fluve has completed over 2,400 projects. Here’s where we’ve been working.

Here’s a question that we get asked pretty frequently: “Why don’t you just let nature take its course?”

While nature can overcome just about any obstacle placed in front of it, that takes time. So, we use the best science available to move systems towards more sustainable and robust conditions to save species that need those conditions as soon as possible. This can be tricky, because when it comes to aquatic ecosystems, the line between “natural” and “artificial” is blurry. Any surface water that you see is almost always much less “natural” than it seems. Even a scene like this is heavily managed. Following urban growth, developers drained wetlands, built dams, and paved over the ground. These actions increased and exacerbated flooding. In response, a watershed management organization was formed, and a dam was built upstream to control the flow. This story applies to countless streams and rivers across the world, and it has for a very long time.

Historically, in the USA, “managing water resources” has meant ditching, damming, and draining surface water. Over time, a lot of these ditches, dams, and impoundments started to take on the appearance of “natural” streams, waterfalls, and lakes. These systems typically fail to support the full range of ecosystem services that evolved in those locations.

Luckily, as we better understand these systems, there has been a paradigm shift. Instead of confining and diverting streams and rivers, we are seeing riverside communities undertake projects to expand and diversify habitat, improve surface water quality, and support more ecologically appropriate recreational opportunities in their waterways. These projects attempt to restore ecological conditions that, in some cases, have been absent for hundreds of years. This is the sort of work that we support every day.

Returning to the original question: why don’t we just let nature take its course? Emma Maris, in her book Rambunctious Garden, has a possible answer: “We’ve forever altered the Earth, and so now we cannot abandon it to a random fate. It is our duty to manage it." #science #ecology #engineering #civilengineering #environmental #fisheries #environmentalscience
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Camas is one of the most important traditional foods in the Pacific Northwest. Following Euro-American settlement in the area, industrial farming and ranching confined productive camas meadows to just 5% of their original range. Since 2002, we have worked with Tribal communities in the area to develop techniques to reconnect and restore meadow hydrology to improve conditions for camas and other First Foods. #environmental #environmentalimpact #environmentalengineering #waterresources #pacificnorthwest #foodsovereignty ...

Like any other structure, dams require regular maintenance. When a dam no longer serves its intended function, maintenance costs can be hard to justify—and dams that fall into disrepair can be extremely dangerous. Over the past century, more than 250,000 people around the world have died from dam failures.

So, in the interest of public safety, communities with dams often decide to remove them. Dam removal is a complicated process, and it can be a highly emotional one. Sometimes dams are important landmarks. Impoundments and spillways can mimic attractive natural features like ponds and waterfalls.

One of the biggest concerns that we hear about dam removal is that it will cause flooding. That’s a common misconception. Most dams are run-of-river dams, which means they do not have any flood reduction role. Consequently, in almost all cases a dam removal will not change flood elevations downstream of the dam while lowering flood elevations upstream. In addition, we carefully design the release of impounded water during a dam removal. This “drawdown” process can take months. After releasing the impounded water, the flow downstream is the same as it was before dam removal, and catastrophic dam failure is no longer a risk.

Although dam removal isn’t the right choice in every situation, it can result in beautifully restored streams and rivers that provide important habitat connectivity and new recreational opportunities.

Pictured: the Pucker Street Dam site in Niles, Michigan on the Dowagiac River before and after removal.

#water #riverrestoration #dam #environmentalengineering #waterresources #habitatrestoration #river #civilengineering
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Today is World Rivers Day! At Inter-Fluve, not only are we driven to heal aquatic ecosystems through applied science and engineering, but we are honored to have our headquarters on the beautiful Columbia River. #WorldRiversDay #riverrestoration #pnw #pnwlife #columbiariver #columbiagorge #environmental #environment #water #riverlife #hoodriver ...

Happy #estuaryweek! Estuaries are important for supporting local economies, protecting against sea level rise, sequestering carbon, preventing coastal erosion, and providing critical habitat. The construction of dams, canals, levees, and other structures, combined with other factors like increased stormwater runoff, is threatening estuaries around the world. There are steps we can take to address this, such as this project to improve fish passage around the Peconic Estuary on Long Island. #estuary #riverrestoration #longisland #habitatrestoration #sealevelrise #climatechange #climateresiliency #EnvironmentalEngineering #fishpassage #environmentalscience #fisheriesscience ...

What happens when a tree falls in a river? In a functioning ecosystem, they provide all sorts of benefits. The branches and roots become ideal hiding spots for young fish and invertebrates, the trunks protect the bank and create pools of cooler and slower moving water, and the decaying leaves and wood become food for a variety of life. In areas where trees were removed, sometimes we need to step in to restart these processes. For over 30 years, we have designed and placed large wood structures in rivers and streams to meet a variety of restoration goals, such as mitigating the effects of erosion and providing habitat for spawning fish. This structure on the Methow River in Washington provides fish habitat while protecting a bridge abutment by pushing flow away from the bank. It also has a “bumper” that protects people floating and swimming in the river. #riverrestoration #erosion #fishing #pnw #pnwlife ...