Waterway Restoration: A Holistic Approach to Improving Fish Passages
Every year, millions of fish migrate between the ocean and their native habitat, navigating waterways across natural landscapes, farmland, and ever-expanding developed regions of highways, towns, and cities. Removal of barriers such as dams, culverts, and levees, has long been recognized as a necessary and viable means to improving fish passage, and good progress has been made in this regard. More importantly, though, waterway restoration as a whole has evolved over the past 20-30 years to encompass a broader approach.
Fish passage restoration is no longer confined to removing or replacing existing impediments. It is also about understanding watersheds and river basins as a whole and implementing solutions that improve the health of a complex ecosystem, improve the ability of fish to migrate and thrive, and ultimately improve multi-species preservation efforts.
Here in the Pacific Northwest, a real sense of urgency has also emerged as 27 West Coast Salmon runs are threatened, including Chinook Salmon whose survival is linked to the recovery of southern resident orca. In response, local agencies and tribes in Puget Sound have launched comprehensive fish restoration programs. Otak has been involved in a number of projects in Washington and the Columbia Basin and has been at the forefront of this shift to a more holistic approach to improving fish passages.
Barriers, Encroachment, and Water Quality
Today, rather than looking at only physical barriers like culverts and dams within a waterway, multidisciplinary firms like Otak take into consideration all of the other factors that impact healthy fish passages. “Twenty years ago, we had this concept of the four Hs: habitat, hydropower, hatcheries and harvest,” Jamie Bails, Otak Senior Environmental Scientist, states, “and while each of these things is important, we have come to understand it is barriers that are preventing fish from getting where they need to go.” But there is more to it, as Jamie further explains, “all of those things can’t be improved if we don’t fix the habitat. Correcting infrastructure like culverts and bridges will help, but ultimately it is the streams that will do the work when we get out of the way.”
What Jamie and the rest of the Water & Natural Resources team at Otak understand is that improving fish passage is not just about the physical barriers, it is also about encroachment on waterways and adjacent habitat. Water quality, sedimentation, and pollution are equally important and present real barriers to fish. Russ Gaston, Senior Vice President, Water & Natural Resources, has 33 years of experience studying and improving fish passages, working in both the public and private sector. He explains “for years, restoration projects focused mainly on removing physical barriers or helping fish pass through or around barriers. What we have seen though, is streams that had polluted water flowing into them did not achieve positive results after physical barriers were removed. Rather, they saw little to no improvement at all.”
For example, Russ and his team worked with Snohomish County for over 20 years to improve fish habitat and remove fish barriers in the French Creek watershed, but restoration of spawning salmon to the upper watershed remained impeded because the water-quality-barrier in the watershed had not been improved. They have since worked with the County and the farmers in the watershed, to restore stream buffers in the agricultural lands, and have developed options to improve water quality in the highly degraded lower reach of the watershed, which the County is evaluating and deciding on which option to move forward on.
Today, Russ says “we commonly focus on stormwater runoff and work to create a stable channel to keep bank erosion to natural rates, which are primary sources of pollutants in a stream. We also use the Benthic Index of Biotic Integrity (B-IBII) to project the health of the stream before and after the restoration is completed.” The work Otak did on the Miller Creek Daylighting project for the City of Burien, Port of Seattle, and the City of Sea-tac is an example of where the team has applied this process.
Multidisciplinary Project Teams
To fully understand what is happening within a waterway and what barriers—physical or otherwise—are having the greatest impact on fish passage, the entire watershed needs to be considered. And this requires expertise and perspective only possible through a multi-disciplinary approach. Optimally, project teams should include structural and civil engineers, geomorphologists, biologists, wetland ecologists, and landscape architects. Russ, who has been involved in a number of fish basin planning projects in Washington, points out that it is not just multiple disciplines weighing in on a project, it is integrated teams working together. “What I thought was an integrated team years ago, is nothing compared to what we do today. Engineers are no longer working in isolation, but are now working together with stream biologists, geomorphologists, landscape architects—all within one firm. This is a key advantage and influences the way we think about restoration,” Russ asserts.
Working closely together, integrated teams have a greater understanding of all the impediments to fish passage and where to focus restoration efforts. This level of data essentially provides a blueprint for identifying failing infrastructure and prioritizing projects. This in turn has the added benefit of not only improving fish passage and multi-species preservation across a region but can also save the various jurisdictions—cities, counties, the state—considerable expense.
Fish passage restoration is only a small piece of what teams like Otak’s Water & Natural Resources team can provide. For example, Otak has a surveying group that is experienced in collecting water resource information. “We are able to do everything in-house, which allows us to go beyond improving fish passages in isolation to really addressing stream restoration as a whole and improving an entire watershed,” Russ states.
Fish Passages and Stream Restoration
There are two typical approaches to designing and improving fish passage. One is an engineered hydraulic calculation with a specific focus on providing the right depth and velocity conditions in a system that targets specific fish species.
The other approach involves stream simulation, which takes into consideration the natural geomorphic processes and seeks to replicate how a stream might have evolved naturally, what is currently impacting channel evolution and how it might be impacted in the future. “Obviously, there are constraints to what we can do—existing roads, cities, and other development—but when we look at streams in this manner, it allows us to come up with solutions that will have a greater impact than improving specific sites in isolation,” Russ states.
With this approach, Otak has been working with cities, counties, and agencies to help them assess where they should be focusing their restoration efforts. “We bring a multi-disciplinary team to assess water quality, water flow, channel degradation, floodplain, and habitat values,” Russ explains. “We’re assessing fish habitats and the connectivity of wetlands, as well as existing infrastructure, regional stormwater management, and integrating our findings into cohesive designs and fish passage restoration planning,” he adds. Ultimately, with such comprehensive data, Otak’s teams are able to give recommendations based on real cost-benefit analyses and offer solutions that benefit the fish and other species on a broad scale. “This is an area where we have been extremely successful,” Russ asserts, “and the advances we are continuing to make in the industry are exciting.”
It is not just firms like Otak that are embracing a comprehensive watershed approach to fish passage restoration. As the industry has evolved and best practices continue to improve with the integration of multi-disciplinary teams, government agencies are also looking at the bigger picture of coastal adaptation and seeking solutions that will not only improve fish passage and aid in multi-species preservation but will also benefit the region economically. Commercial and recreational fishing and tourism are all linked to fish preservation. Economics aside, the real benefit, as Russ points out, “is that we’re restoring natural processes, which holistically lifts the entire system, improves the resilience of the watershed, and benefits all aquatic and riparian life.”