The Search for a “Fish-Friendly” Tide Gate

I never thought that I’d learn so much about tide gates. I’m a biologist, so I know about fish identification, important measures of fish habitat, and how to catch fish in a scientific context. But why would I need to know anything about tide gates? Well, tide gates can have a big impact on the quality of habitat and the ability of fish to enter and exit these habitats. Tide gates along with levees (or “dikes”) are used in tidal areas of the Columbia River and other coastal rivers to help keep water out of the natural floodplain of the river. Tide gates let water out when the tide is receding and block water from entering as the tide comes back in. The floodplain can then be used for cropland, grazing or other development without the threat of seasonal or daily flooding.

Old-style, top-hinge, steel tide gates are difficult for fish to get past and don’t allow any exchange of water.

The Columbia River has experienced over 100 years of flood control. Through changes in river flow from dam regulation and the installation of levees and tide gates, the amount of shallow water habitat in the Columbia River has been greatly reduced. It’s estimated that over 60% of historical tidal freshwater areas of the lower Columbia River has been lost. Much of this lost habitat is behind levees and tide gates. These areas were where young salmon grew and hid from predators before heading to the ocean. Now, these young salmon have difficulty accessing feeding areas behind the tide gates and much of the habitat behind the gates is of poor quality. The low quality of the habitat is mostly due to the lack of water exchange between the river and the slough habitat behind the gates. This can cause higher water temperatures than salmon can tolerate. These higher temperatures can also be good for non-native fish species, like largemouth bass, that will prey on young salmon.

Chinook Salmon

Fortunately, restoration is taking place in parts of the Columbia River Estuary to recover some of this lost habitat. These restoration projects can take many forms. Sometimes it is possible to remove a levee or tide gate and allow the river to spill into its historic floodplain. Other times, flood protection must be maintained, so the options available for land managers are more limited. In these situations, new tide gate designs are being tested to determine if they allow better fish passage and water flow between the river and flood plain.

Julia Butler Hansen National Wildlife Refuge was created in 1972 for the protection and management of the endangered Columbian White-Tailed Deer. Land managed by the refuge includes uplands, riparian area (land along the water), wetlands and sloughs. Restoration to improve aquatic habitats, including the replacement of older tide gates with newly designed tide gates, has been occurring since 2007. Because the primary purpose of the Refuge is to protect White-Tailed Deer, removing levees to allow natural flooding of the refuge is not an option. Instead tide gates designed to allow improved fish passage and tidal water exchange have been installed with the hope that the aquatic habitat behind the levees improve and that fish have an easier time passing the gates.

My job is to determine if these new tide gates have improved fish passage (movement through the gate) and the aquatic habitat behind the gate. One way that we do this is to capture fish that enter through the new tide gates and compare the numbers and types to those that we caught when the old tide gates were in place. We also compare the numbers and species of fish captured to sloughs without tide gates to see how closely the sloughs with the new tide gates resemble sloughs without any tide gate at all. We also look at how temperature and other things to determine if the quality of the habitat has been improved by the new tide gates. In addition to all this, we also attempt to determine how long fish stay in these areas and how fast they grow.

Trapping fish entering through new tide gate.

Biologists collecting fish with a beach seine.

We will be collecting information on fish and these habitats through the spring of 2012. At that point we expect to have a pretty good idea of whether there is an improvement in fish access and habitat quality and, if so, how much of an improvement. If results are good, these types of tide gates will likely be used in other restoration projects where some level of flood control is needed but improvement for fish is desired.

Newer-style tide gates are designed to improve fish access and exchange of water.

Submitted by Jeff Johnson

Tryon Creek Restoration Efforts

Yesterday, I went for a walk in the park. That’s right, Tryon Creek State Park. Jen and I were conducting the biweekly spawning ground survey in Tryon Creek. For those of you who are unfamiliar with the creek, it is a relatively undisturbed urban watershed. Most of it lies within the boundaries of the state park in southwest Portland. Historically, the creek probably supported abundant populations of anadromous fish. Now it seems that most of those fish populations may be depressed. One of the reasons for this may be a culvert running under Highway 43 which was constructed in the late 1920s. The design most likely blocked lamprey migration and was not ideal for salmonid passage, either. The baffles within the 400 foot long culvert were not fish friendly and the drop at the outlet of the culvert was too high for fish to negotiate at times.

Back in 2003, the City of Lake Oswego secured a Metro Greenspaces grant to analyze the best alternative for replacement or removal of the culvert under Highway 43. Soon the Oregon Department of Transportation came up with some more money. Lots of other partners became involved as well.

In 2006, our office began a project to monitor the effectiveness of restoration actions. We began by determining the existing habitat conditions and the presence, absence, and distribution of lampreys and salmonids, both above and below the culvert. Larval lamprey of two species were captured below the culvert, but none above. Cutthroat trout, steelhead/rainbow trout, coho, and Chinook salmon were found both above and below the culvert.

Culvert Baffles - Before and After

In 2008, the baffles in the culvert were replaced and the drop at the outlet of the culvert was reduced with a series of natural step pools. Restoration efforts are ongoing in the portion of creek below the culvert to improve fish passage. We continue to monitor the presence of fish in Tryon Creek to determine the success of the restoration effort to improve fish passage through the culvert.

Fish Passage into Culvert - Before and After

In 2009, no lampreys were found in any section of Tryon Creek. The same species of salmonids were found both above and below the culvert. Cutthroat trout spawning activity was observed above the Highway 43 culvert as well. Still, it is too early to determine the effectiveness of the restoration work.

We will continue to sample Tryon Creek to further our understanding of all fish species within the system. Monitoring will provide further evidence for the level of success of the improvements made to the culvert and to the creek below the culvert as well as the efficiency of passage through the culvert by lampreys and salmonid species.

For more information, read the latest report.

The Oregon Chub - A Little Fish on the Road to Recovery

The Oregon chub is a small minnow found only in the Willamette River basin in western Oregon. Adults are typically less than 3.5 inches in length. They live in habitats such as beaver ponds, side channels, and flooded marshes, with little or no water flow, silty bottoms, and aquatic vegetation for cover for hiding and spawning. Historically the Willamette River had many side channels, oxbows, and overflow ponds that provided ample habitat for the chub. Periodic flooding of the Willamette also created new habitat and transported the chub into these areas to create new, or help sustain existing populations.

There are many reasons for the severe decline of Oregon chub populations. Construction of dams and flood control projects changed the Willamette River significantly, preventing the formation of new habitats and the natural dispersal of the species. Other factors responsible for the chub’s decline include: habitat alteration such as channelization and bank hardening, the introduction of non-native fish and amphibians, herbicide and pesticide runoff from farms and roadways, and diversions.



The Oregon chub was first listed as endangered in 1993. In 1998, the U.S. Fish and Wildlife Service published a recovery plan for the chub. The goal of the plan was to reverse the decline of the Oregon chub by protecting existing wild populations, re-introducing chub into suitable habitat throughout its historical range, and increasing public awareness and involvement. The criteria set forth in the plan for downlisting the species to “threatened” was to establish and manage 10 population of at least 500 adult fish. All of these populations had to exhibit a stable or increasing trend for 5 years as well.

Along with the efforts of other agencies, active programs have been put in place to protect Oregon chub habitat. Critical habitat was designated in March of this year. The species’ status has improved recently. On April 23, 2010, the U.S. Fish and Wildlife Service changed the Endangered Species Act classification of the Oregon chub from endangered to threatened.

To learn more about critical habitat, visit http://www.fws.gov/endangered/what-we-do/critical-habitats.html

To learn more about the Endangered Species Act, visit http://www.fws.gov/laws/lawsdigest/esact.html

Submitted by Donna Allard.

Habitat improvements in the wake of a dam removal

Last month I got outside and saw first-hand how stream habitat can begin to change following the removal of a dam. Hemlock dam, built in 1937 on Trout Creek in the Wind River watershed, was initially constructed to provide power and water to the Civilian Conservation Corps and Forest Service. Trout Creek provides critical habitat for Lower Columbia River steelhead, listed as threatened under the Endangered Species Act, but the dam (even with a fish ladder) effectively blocked fish passage to spawning grounds and degraded habitat for fish downstream by increasing water temperatures in the creek.

Hemlock Dam, 2006 (photo by USFS)

In the 1990's, several federal and partner agencies decided that the creek should be restored and the dam removed to benefit the steelhead and other native fish in the community. The Fish Passage Program under the Fish and Wildlife Service contributed approximately $250,000 along with funds from partners totaling $2.1 million, and in the summer of 2009, action finally took place: the pump house was removed, the creek was diverted, Hemlock dam was dismantled, the creek channel was reconstructed, invasive weeds were removed, and riparian habitat was enhanced with native shrubs and trees.

Today, one year later, you can see the benefits of the dam removal project. Most notably, Hemlock Lake is no longer there! In its place is a meandering creek channel, with small trees planted on the banks that were previously under water. It will take time for the trees and brush to fill in, but in the meantime, the restored section of Trout Creek has likely been recolonized with lotic aquatic insects for fish to eat, sediment that had built up behind the dam over the years has been removed, and temperatures are no longer near the lethal limit for fish. Additionally, removing this barrier has opened upstream habitat for spawning and migrating steelhead.

Hemlock Lake, 2006 (photo by USFS)

The same view as above in June 2010, only it's now Trout Creek instead of Hemlock Lake! (photo by Donna Allard, USFWS)

With this improvement to Trout Creek, I'm looking forward to seeing how the habitat changes in the project area in the years to come. Be sure to take a look at the Forest Service's website about the project - it even has a video of an adult steelhead that moved up through the project area just hours after flow was restored through the creek bed! The video also shows a tractor moving large woody debris into the floodplain of the stream to enhance fish habitat...word gets out fast among the fish, it appears!

Common Carp - The Biomass Black Hole

Nonnative species can have extremely harmful impacts on ecosystems. Take the case of the common carp in North America – some people call it “the perfect invader”. It possesses many traits that make it great at exploiting new habitats: high growth rates, high fecundity (a 5-pound female may produce half a million eggs a year), tolerance to range of temperatures and oxygen concentrations that other animals don’t have. This fish was intentionally introduced widely in the 1800s thinking they would be a great food fish like it was in Europe. Alas, the idea never caught on. Carp, at least in high densities, can degrade water quality and denude aquatic vegetation. Thus, they can be detrimental to sport fish populations as well as waterfowl and shorebirds.


I had an opportunity to participate in the renovation of a small lake in north-central Nebraska during my graduate work. The 158-acre, shallow, prairie lake had an abundant common carp population. This lake certainly had been affected by the carp, as it contained almost no submergent aquatic plants and algal blooms were abundant. The water often looked like chocolate milk. As part of an ongoing research project, we decided to remove the entire fish community. Three airboats were used to apply the liquid rotenone (a plant-derived fish poison) and one prop boat was used to distribute some powdered rotenone as well. In addition, an amphibious vehicle equipped with a plant sprayer was used to get into the hard to reach backwater areas and cattails beds of the lake to ensure the chemical was distributed throughout. We didn’t want to leave any hiding spots for the fish we were trying to eliminate. Two small carp of opposite genders left alive could ruin an expensive operation!

The first small fish started surfacing within an hour of first adding the chemical. Toward the end of the day numerous adult carp were observed struggling at the surface. The biggest part of our job came after the rotenone application. We needed to estimate the number and total weight of all fish species in the lake. We walked certain areas of the lake shoreline and counted every dead fish. These counts were then used to estimate how many fish were in the entire lake. We know that lakes have many fish living in them but it sure is impressive to see all of those fish at one time! By the third day we wondered if we should be on the “Dirty Jobs” television program as the fish definitely were getting ripe! All in all, we believe that the lake contained about 5,412 adult common carp and 2,658,249 fathead minnows. Plus, these are probably underestimates because many fish sink to the bottom and may not float in time to get counted!


It will be interesting to watch potential changes in the lake after the treatment. Will the water clear up and new aquatic vegetation sprout up next year? Only time will tell. However, we certainly hope so! Both the sport fishes and the waterfowl should benefit from increased amounts of submergent aquatic vegetation. Without the use of rotenone to remove the undesirable fish, we could never have attempted this project. Breaking news on this ongoing project – after several years (post- carp removal) without noticing any increase in vegetation – all sampling sites now have an abundance of aquatic vegetation. It looks like the lake might be “recovering”!


Malheur Lake and Malheur National Wildlife Refuge has a carp problem. A big one. Malheur Lake alone (not counting its tributaries) roughly averages 37,500 acres. If the carp density was the same as the lake in Nebraska (34 carp/acre), extrapolating for lake size, Malheur Lake could contain almost 1.3 million carp! In terms of biomass, at a rate of 234 pounds/acre, this translates into almost 8.8 million pounds of carp swimming in the lake. Just think if you could convert this biomass of carp into plants and invertebrates! The lake is denuded of vegetation and only produces a quarter of the ducks that it did in the ‘40s. Although there are likely several potential reasons for this, the lack of vegetative habitat and associated invertebrate prey items is surely related. Earlier this year a coworker and I attended a workshop at Malheur National Wildlife Refuge where refuge staff and some of the best “carp minds” in the country gathered to discuss Malheur’s problems and brainstorm an attack plan. A thorough assessment of the problem is ongoing. A recent article in The Oregonian also highlighted the problem: http://www.oregonlive.com/news/index.ssf/2010/05/fish_invaders_are_eating_birds.html. Finally you can visit Malheur NWR’s Aquatic Health page to learn more about this issue: http://www.fws.gov/malheur/wildlife/aquatichealth.htm.

Submitted by Jeff Jolley.

Inspiring the Next Generation of Nature Lovers

Connecting people with nature is one of the top conservation priorities of the U.S. Fish and Wildlife Service. One of my most favorite and most rewarding duties as a biologist is working with and teaching young people about the natural environment. Recently I had the unexpected opportunity to share a meaningful outdoor learning experience with some children very dear to my heart – my six year old niece Amelia (Mia) and four year old nephew Max.
When my husband and I first agreed to watch the kids, we were a bit worried because we didn’t have television or any age appropriate toys or video games in the house to keep the kids entertained. Thankfully, the education and outreach coordinator at my office (Donna Allard) set us up with an assortment of fun ideas and activities for the kids.


When my niece and nephew arrived, we presented them with their very own magnifying glasses. The kids absolutely LOVED them! My niece didn’t set hers down the entire time she was at our home! Max and Mia had a great time looking for things to inspect under the glass. Some of their favorite “case studies” included: broccoli flowerets, garden spiders, a dead bee on the window sill and a scab on Mia’s leg – excellent gross-out factor!



After dinner the kids asked if they could watch some TV before bed. It was time to bust out the big guns – owl pellets. Another success! After some assurance that owl pellets were not poop, the kids literally dug right in. For over an hour we picked fragments of bone and separated bits of fur from tiny skulls and vertebrae. Max and Mia deemed this activity “very cool” and decided they loved to “explore” things. My niece even expressed her desire to become a scientist when she is older.

By the next morning, television was the furthest thing from their curious minds. After breakfast the kids sampled some of the first strawberries and tomatoes from the garden, helped us water the plants, created a number of stone pagodas or “castles” in the yard, looked for spiders and other creepy crawlies to inspect under the magnifying glass, collected pits from our cherry tree to plant at home and simply enjoyed playing outside. Who would have thought the kids would have so much fun simply observing and interacting with nature!


As an adult, connecting children with nature is an important, EASY and very rewarding experience. Whether it is sitting around a campfire, planting a garden, visiting a park, going fishing or taking a walk or bike ride together, sharing outdoor activities with children and encouraging them to explore and ask questions about the environment helps them develop an important appreciation for nature and nurtures a love for the outdoors that will last a lifetime. Who knows, you may even end up inspiring a budding scientist or future environmental steward in the process.

Although it’s going to be tough to top the owl pellets, my husband and I are looking forward to sharing many more outdoor adventures with Max and Mia!

For more information, Let's go outside!

Submitted by Jennifer Poirier.

Refuge Assistance

One of the really fun parts of my job is called “Refuge Assistance,” which means working with National Wildlife Refuges in our area on a variety of issues concerning fish and aquatic habitats. Our area covers the Washington and Oregon sides of the lower Columbia River and all of Oregon with the exception of the Klamath River basin, which is covered by Service offices managed out of California. There are over 20 individual Refuges located throughout our area. Most are located along major rivers or the coast, and their size ranges from a few hundred acres up to several thousand acres. However, there are three refuges that cover well over a hundred thousand acres. These are in eastern Oregon, and the majority of one extends into Nevada.

Electrofishing on the refuge.

Refuges were established for several different purposes. Many were formed to provide habitat for various species, whereas others were established to provide certain types of habitats or for specific species or populations, like the Columbian white-tailed deer or Aleutian cackling geese. In addition to a refuge’s purposes, management is also directed toward other priorities so long as the other priorities are compatible with the refuge’s purpose. These priorities broadly include Service trust resources—migratory birds, threatened and endangered species, interjurisdictional fish, and marine mammals; biological integrity, diversity, environmental health (also called BIDEH); and compatible public uses. Overall, BIDEH refers to the native plants, animals, and habitats of a refuge, and conditions that support them. Public uses include wildlife observation, wildlife photography, interpretation, environmental education, hunting, and fishing.

Assistance that our office provides ultimately is intended to help refuges achieve their purposes and address other priorities. Doing so can involve several types of activities. One example of an activity is inventory work, which involves determining the types of fishes and their habitats found at a refuge. Another type of activity is effectiveness monitoring, which assesses such actions as aquatic habitat restoration so that the success of a restoration project can be evaluated. Technical assistance is a broad type of activity that covers such things as conducting literature reviews, designing studies to inform management decisions, and participating on technical planning teams.

Checking a fish trap.

The wide variety of refuges, with their associated purposes and other priorities, makes working with them a great part of my job. We have an annual workshop to present findings and discuss aquatic issues. Summaries of the workshops are available at: http://www.fws.gov/columbiariver/programs/RAP/refuge.html if you are interested in learning more about Refuge Assistance.

Submitted by Sam Lohr.