The Beaversoils of Onion Flat and Tualatin

Reading early descriptions of the Tualatin Valley, they are all focused on the valley’s potential in agriculture. This theme is similar throughout the Willamette Valley; settlers and farmers did not think about the valley in any other way but for its readiness for agriculture. Considering this all-consuming focus, the traditional native nature of the land had very little chance. All descriptions of Nativeness were tinged with how useless they were or how wasted the land was if it was not prepared for agriculture.

Native people had been removed to reservations 50 to 80 years previously (1856), and they had no voice in how white settlers thought about and changed the land to fit the needs of American “civilized” society. Their needs for hunting, fishing, and gathering native foods were never considered when changes were planned in the valley; engineering projects were initiated to increase and maximize the ability of the land to grow crops. If a wetland were in the way, it would be drained and destroyed to make way for development. Native plants had no commercial use; they were labelled weeds, and no space was allowed for them. The situation today is dire, with an estimated 1% of the valley wet prairies remaining.

“Specific to the Willamette Valley, the report noted that an estimated 72 percent of the original
riparian and bottomland forest is gone, as well as an estimated 99 percent of the valley’s wet prairies,
88 percent of upland prairies, and 87 percent of the upland forests at the margins of the valley. The
report concludes that this transformation of the valley’s landscape “has fueled our economic growth
and settlement for over 150 years. Yet this transformation has left a mark on our environment and a
debt to pay” (OPB 2000) landscape.” (page A-4, US Fish and Wildlife, Willamette Valley Conservation Study, 2017. Accessed 3/26/2026 )

In the early 20^th century, there were few environmentalists, and developers of the land seemed to think there was no end to the resources it could produce. When lone naturalist William Finley complained about how damming the rivers would destroy bird habitat, his singular voice was ignored. It is because of these acts of destruction of native lands, lack of any care or responsibility to the earth, that have Tribal and native scholars ask today, who will speak for the animals, plants, and fish, who will speak for the rivers and forests? They had no voice to defend them when the water was being drained from the soils of the valley, destroying many ecosystems and causing the collapse of traditional native environments in every system. Seemingly irreparable harm has been committed due to the need for development.

While environmentalists and tribes are now working to conserve, recover, and restore natural areas, they are challenged by the continuous push for more destruction and more wealth extraction from the already radically altered lands.  People living today have a lack of long-term perspectives as to how much the land has already been altered in the past 140 years. Few people living in the Willamette Valley understand that it was a series of extremely wet prairies, full of ponds, lakes, sloughs, marshes, swamps, and swales. The wetland character of the valley made it amazingly “wealthy”, a never-ending source of native foods for millennia, and the nutritious soils of the valley are the reason that agriculture does so well. But even the “wealthy” lands have their limits. With moisture drained continuously from roughly 50% to 80% of the agricultural lands, the land is becoming exhausted and, over time, will recover more slowly than previously. As well, the former reason for agriculture- to create food for an ever-expanding human civilization- is no longer strictly true. In many areas of the valley, grass and grass seeds are the dominant crops, and this type of resource feeds few people.

 

Case study: Onion Flats

Another peat wetland has come into focus. In 2023, I addressed the history of Wapato Lake and Lake Labish, two of the major peat wetlands of the valley, noting how ditching and drain tiling had radically altered these traditional lakes and wetlands. I knew there had to be more, since descriptions of the valley since its earliest descriptions in print suggest that the valley was a vast series of wetlands and swales.

Onion Flat is a peat “beaversoil” wetland on the western side of Sherwood. It is today bounded by town developments on the eastern side of Hwy 99, while the Tualatin National Wildlife Refuge contains the western side of the wetland. The Tualatin NWR today uses the excess water of the wetland to create restoration lakes and ponds for native plants and habitat for native wildlife, especially migratory wetland birds. There are extensions north and east of Onion Flat, suggesting it was part of a complex of several peat wetlands. Other complex features are named for the settler farmers who planted them in onions, Mulloy, & Cipola. The former onion fields of Mulloy and Cipola today appear to be developed over, but more eastwardly, the wetlands extend into the city of Tualatin. The Onion Flat area is fed by Rock Creek, and Onion Flat appears to be part of an old oxbow of the Tualatin River, making the junction of Rock Creek and the Tualatin a large spreading wetland.

Oregon beaversoil, or sometimes called “Beaver dam,” was noticed early in settlement as a great onion-growing area. Lake Labish is perhaps the best-known onion area in Oregon (in my opinion), but Onion Flats and other wetlands in and around Tualatin are also well-known for onion growing.

Tualatin City has a well-developed, but dated (1995), wetland inventory, and uses its large wetland resources to create parks and recreation areas. Their Natural resource inventory lists many species, but there is little consideration for the Native American plant resources that tribes are interested in. The inventory notes for Hedges Creek “The channel is well-defined in most areas, and its course has been altered due to past agricultural activities” (p. 9). The Tualatin wetlands, however, are suggestive of what the Onion Flat landscape would have been like previous to dredging and draining for agriculture. Since much of the Tualatin wetlands appears to be restored and conservation land, and they did not consider Native American needs, their restoration may not be as comprehensive as Tribes would want at present.

The information and programming for parks available from the City of Sherwood is opposite that of Tualatin. They have not invested in their wetland heritage at all and simply list the Onion Flats area as a FEMA Floodplain, problematic for the area. The condition of their parks and park development (small and dry) is confusing considering their logo suggests a natural environmental character, including a large wetland with reeds and a goose flying over it.

Annual and semiannual floods are a natural part of the valley environment; floodplains are amazing and diverse resource areas that are necessary for the health of water and the ecosystems. The destruction of wetlands leads to the extinction of species and has many effects on water quality. Investments into preserving wetland areas, even for recreation, rather than destroying them, will benefit everyone, plants, animals, and humans.

Onion Flat is described as a prime onion-growing area. Some of the first newspaper accounts are about the difficulty of placing a road through the wetland and the need for a bridge. The Onion Flat Bridge was a major development for the area that allowed newly developed automobiles to travel through the area. In the 1920s, newspapers even advertised for Onion field tours, where people could have a picnic lunch and join a tour of five or more onion fields, including Onion Flat. Oregon newspapers in the first decades of automobile travel were the principal means of advertising to the public where the good roads were, and the routes were being developed for excursions outside of the cities.

An example of this ran in the Oregon Daily Journal, on November 8, 1918, a full page (p3) infomercial story of the culture and developments in the Tualatin valley, under the title of Tualatin valley, Wonderland of Fertility, Progresses with Highway. Subtitles of the story include Tualatin Valley has good roads and fertile land & Excellent highways prove great factor in upbuilding of Prosperous Oregon Community, etc. But in the midst of the infomercial is a description of Onion flats. “It is comprised of rich black soil, known as Chocolate Loam, which will produce any and all the products adaptable to Oregon’s climate. … The fertility of the soil renders it unnecessary to project any form of irrigation. In fact, tile drains have been used in some places to dispose of an over-abundance of moisture.” … what is known as Beaver Land is an interesting feature of the valley, where rich black silt, deposited as a result of a beaver dam constructed a century or more ago in the Tualatin River and thereby diverting its course, spreads over an area of several hundred acres. This section, sometimes called “Onion flat,” produces a yearly crop of onions of great value. The story continues to address the other foods produced in the area, apples (Spitzenbergs and Winesaps), loganberries, prunes, Jersey and Holstein cattle, Angora goats, Berkshire and Duroc Pigs, oats, wheat, clover hay, as well as dairy farms, and opportunities to buy cider pressed at the farm. In 1919, the nation was in the Prohibition era, and juices (apple and loganberry) were a developing beverage for bottling.

A more recent story by Loyce Martinazzi describes the history of the Onion flat beaversoils.

“After the Missoula floods raged through the valley some 13,000 years ago, beavers came and built dams, and the great swamps they made became filled with vegetation which would decompose, creating deep, rich soil.” And “By 1870, farmers began to drain the swamps, first using tree bark as the conduit. Erwin Cummons was the first to start growing onions in the Sherwood flats. But there were other beaver dam lands, in Mulloy, and even here in Tualatin” (Martinazzi, Tualatin Life).

Martinazzi’s story even addresses the native heritage connected with the flats. In previous essays, native actions were limited to harvesting wapato and other marsh plants, but the lakes and swamps must have seen a lot of hunting and fishing too.  “As the farmers plowed, they plowed up thousands of arrow points that the native Atfalati had used to hunt game.” At Wapato Lake, 19^th and 20th-century descriptions were of thousands of waterfowl, dabbling ducks, known today as canvasback ducks, which were known to frequent the lake during their twice-annual flyovers. If the Onion Flat area had similar flyovers of waterfowl, then duck hunting would have been very good. Lake Labish to the south was also noted to have been the habitat of numerous small, medium, and large mammals, and they, too, would have been hunted. A story from 1961 suggests a Sherwood man in a canoe died while duck hunting at Tualatin (The News Review, March 20, 1961, p. 3).

The Onion flats area and the larger complex extending into Tualatin come from significant annual overflowing of the Tualatin River, and likely seasonal overflowing in a moister climate up to about 100 years ago. Beavers dammed the creeks and contributed to the wetland complex in the area. Climate change has increased temperatures since the Little Ice Age. We are today warmer, and the warming trend is increasing due to human development. There is overall less water in the ground, and ditching and draining tiling for over a century has contributed to less water in the system. Unchecked human development has crowded out native animals and plant species, and development pressures continue. As of this month, March 2026, there is a proposal to place a battery storage facility in Sherwood, a development, if successful, that will surely cause pollutants to enter the remaining native systems and further destroy the ability of the Native ecosystem to survive.

 

Ethnographic sources do not give us much help in locating a Tualatin village near here. Most villages in Zenk (1976) suggest they were in Chehalem and around Wapato Lake and north. Missing is a village note for the Tualatin to Sherwood area. Ethnographic notes are spotty at best, and it seems likely there was a village near there, especially since the wetland system had nearly the same resources as Wapato Lake. Some villages became extinct in the settlement era, since the areas along the Willamette and French Prairie were settled in the 1830s, because of a massive epidemic of malaria, which killed up to 97% of the Indigenous peoples of the region (Boyd, The coming of the spirit of pestilence, 1999). As such, the people who were at Tualatin and Sherwood would have been subjected to colonization and diseases early, and their disappearance or movement caused a lack of knowledge about them in the record. Elsewhere, I have hypothesized that there is a Wapato area between Salem (Lake Labish) and the Columbia River where wapato was more plentiful. South of Salem and the wapato patches are very sparse, which could be an effect of pollution and dredging, but may mean there was less abundance of wapato in the southern valley. There are no records of wapato at the Onion Flat location, besides what they are restoring at the Tualatin National Wildlife Refuge. The wapato at the refuge is plentiful, and this indicates that the area is perfect for growing wapato. It seems reasonable to assume there was Wapato in the Onion Flat area as well. Perhaps coring of the peat area would reveal wapato pollen and prove this was the case.

 

Limitations to human historic perceptions

Now, people rarely see standing swales, they rarely experience even light flooding (except in a few river basins like the Luckiamute), and they hardly see marshes or swamps, since all of these features of the valley have been drained. These were common features in the valley up to 1920, and yet they are gone. With their disappearance, we no longer experience flights of tens of thousands of geese or ducks; their occurrence was very common in metropolitan cities like Portland only 100 years ago. We are limited by our short-term lifespans, and so it’s tough to convince the public that development has gone too far, because they have little information or experience about what it was like originally.

This makes the idea of recovering this history very important. Most people working in environmentalism at any level do not know what the land was like previous to their experience, and without good environmental history, they may never know. As such, conservation and restoration projects seem to proceed without knowledge of what the land was like, and teams of volunteers will work hundreds of hours on projects under assumptions of what it was like. This is where ideas of camas prairie and oak savanna become important. The assumption that the prairies were either oak savanna or camas prairie is the prevailing theory. Generally, these projects proceed without tribal collaborations, without a sense of fire stewardship applied to the valley prairies and foothills by the tribes. In a sense, the visions of anthropogenic landscapes are close to the mark, but the traditional landscapes were more diverse and varied than we know. And then, rarely in contemporary restoration projects is there any plan to harvest the food produced by the restored landscapes, which is the original reason the tribes stewarded and modified the landscapes so that they would benefit from the food produced.

Tribal World Renewal Stewardship (TWRS)

It takes much research to find accurate descriptions and interpret previous settler writings to understand what the land was like. Tribes also have oral histories and elder knowledge, a level of knowledge few access. Recovery of this information is a step many organizations ignore in favor of proceeding with their projects. There is value in understanding the character of the land deeply so that we may make plans for true landscape recovery. When tribes proceed with restoration projects, they are concerned with the land, the plants and animals, but also the restoration of their culture. Their concerns are multifaceted since tribal peoples have been colonized alongside their lands, and their vision is to restore the land with their culture.

I call this mission and vision, Tribal World Renewal Stewardship. In this area of the Northwest, many tribes feel spiritually connected to their land and communicate with it as if they were relatives. Their mid-winter ceremonies, for tribes like the Tolowa, are called “Nee-dash,” called by anthropologists “World Renewal,” are necessary to restore the world and its wealth (food) each year. All tribes in the region had some version of this. And so, when tribes today are working on restoration, they are less concerned with individual plants but are working at various levels to restore the land, restore their culture, revive their spiritual connections, all necessary connections of relatedness. The program of TWRS is regional, it is international, with tribes and scholars working with and learning from each other, networking to recover a healthy connection with their land. We all rise together.