
In 2017, Kathleen Guillozet began her Outside Voice blog, "Houselessness in Natural Areas," with a prompt: “How can we do a better job supporting unhoused people and sustaining our natural areas?” The training she and others led at the time was a shift in focus from natural areas to the unhoused people who relied on them.
In the four years since, we find ourselves in the same struggle to understand the needs of both. In preparation for the panel discussion on “houselessness and the environment” at The Intertwine Alliance's recent summit, we looked for some answers in our water quality data. What we found might surprise you. There really isn’t data showing measurable impacts from houseless people. The measurable impacts are from the housed community.

We often hear this line from the public when the topic of houselessness and the environment come up in conversation:
Oh no, homeless people are trashing the creek!
It’s often followed by this line from government types like us:
We need to quantify the impacts of the houseless community on our streams and natural areas.
While this sounds like a reasonable scientific approach, it occurred to us that there is a certain objectivity that is missing here.
The scientific method is a system of inquiry based on an observation. We form a hypothesis to try to explain the observation, and then we conduct an experiment to see if our predictions based on the hypothesis are supported. If the science is repeatable and additional studies support the original hypothesis, we might say that we have gained some insight into the drivers of the observation. This process is based in objectivity.
To understand the impact of houselessness on the environment, we need an observation of the impact. We assume that “trashing” means destroying, ruining or otherwise damaging a stream’s health in some way. However, it could simply mean that there is “trash along the creek.” By leading with an assumption that we can measure the impact of houselessness on the environment, we unintentionally create a bias. This is a confirmation bias where we would tend to seek information that reinforces our existing beliefs and ignore information that contradicts our beliefs. We might ask instead:
How significant is the contribution of houselessness among other sources that make up stream impacts?
We highlight this because we have seen how our attitudes and biases can get in the way of how we process the science around houselessness and the environment. If there is a negative bias baked into the approach from the start, we cannot do good science. We need objectivity, or at least, an acknowledgment of our biases.
How different would our conversations be if we called it “surviving outside,” instead of “illegal camping"?
Does the existing data support the assumption that houseless communities have a substantial impact on water quality?
Litter and household debris, like plastic wrappers, paper or other solid rubbish, typically doesn't lead to exceedances of state water quality standards. While litter is unsightly, these materials are largely inert or non-toxic to aquatic organisms. An exception here, though, is the release of “low molecular weight” plasticizers. These chemicals tend to escape to the air as plastic degrades, so they are of relatively lower water quality concern. In our streams, and in stormwater, concentrations of these particular plasticizers are typically below laboratory detection levels.

It is true that plastic litter contributes to the load of microplastics in our rivers and ocean. However, according to the literature, this contribution pales in comparison with the two largest sources of microplastics: synthetic textiles and tire particles, which make up 2/3 of microplastics found in the ocean. These particles are released when we do our laundry and drive around town. The impact of plastics from unhoused people is difficult to quantify because of the comparatively higher pollutant loads from the housed community.
Many in the conservation community have observed trampled vegetation, cut trees and compacted soil, where people have repeatedly placed their tents. Despite the potential decrease in stream shade cover, we do not have stream temperature data that shows increases tied to these encampments. This is largely because upstream land uses contribute so much to high stream temperatures. The inline ponds and decreased stream buffers in residential, commercial, agricultural and industrial areas have reduced the riparian shade cover along our streams. The stream temperature in Johnson Creek, for example, exceeds the state water quality standard from the headwaters all the way to its confluence with the Willamette River.
Many cite human feces from houseless encampments as the biggest concern for water quality. Surprisingly, our local data does not validate our concerns. In the City of Portland, field crews have observed feces and toilet paper along the stream. However, there are no observable changes in water quality. Their ambient monitoring data does not show increased E.coli concentrations downstream of houseless encampments. Similarly, the City of Gresham’s 20-year data collected from a site downstream of a large encampment along the Portland and Gresham border shows no increase in E.coli bacteria concentrations. This is noteworthy, because when we have seen spikes in bacteria counts, they have been the result of pet wastes thrown over backyard fences to streams, livestock in unfenced streams, failing septic systems, and overflows from the combined sewer system.
Could it be that the impacts of houselessness on the environment are not as we assume?
It is very likely that housed people have impacted the stream and riparian areas for so many years that relative signal from the unhoused community is very small. As stormwater managers, we are aware of many types of water pollution, including heavy metals and tire chemicals from cars, pesticides from lawns and nurseries, and other chemicals used around the house. We have streams modified into straightened channels. We have hundreds of fish barriers and numerous introduced non-native species. We see water quality impacts from the uppermost headwaters of a stream. According to local clean-up data from the county and local environmental organizations, most of the trash occurring in local streams originates from illegal dumping by the housed community. So among these many impacts, finding a signal from a transient group of people who use the stream corridor may not be possible.
Are we assuming the worst of the houseless people because of our bias against them?

It is interesting that while we are well aware of the broad impacts from the housed community, the majority of us do not necessarily dislike these people for causing these impacts. They are a part of the housed culture to which we currently belong. We often consider these impacts as unfortunate side effects of how we live.
In contrast, there is a certain vitriol toward those who are unhoused. If you’ve ever read the comments in your neighborhood online social group, you've probably seen quite a lot of victim-blaming, too. These commenters really hate seeing trash. It is understandable, especially if the littering occurs in your neighborhood. We might see it as a reflection of our common values. For those volunteers and professionals who have planted a tree along a stream, there is frustration of having someone undo our hard work. This is understandable, too. Unhoused people, at first blush, seem not to value things in the same way as those who are housed. They might seem culturally different, despite that we do not quite understand where they are coming from. This is probably because many of us have not walked a mile in their shoes. We may be creating a cultural divide because of the circumstances of how we are living.
Our assumptions about the impacts of houselessness on the environment are similar in some ways to the falsities that have perpetuated racism throughout history. In his book, Stamped from the Beginning, Ibram X Kendi gives many examples of pseudo-science and misinformation that have been used to validate white supremacy. False claims can be extraordinarily durable, even when they are debunked repeatedly. We can share our data, but will anyone believe what they see? Or is our presumption of the impacts of houselessness already too deeply ingrained into our cultural beliefs to question it?
We often use the term “illegal camping” to describe what we see when people are sheltering outside. We call it “camping” because we see tents that we use when we go out to restore ourselves on our days off. Camping is a recreational activity for housed people. It is a cultural behavior. It is “illegal” for the unhoused in some places because of an administrative policy. It is not “illegal” because it goes against our ethics and moral convictions. For an unhoused person, sleeping in a tent is not a recreational activity. For many it is a means of survival. It is an act of self-preservation. How different would our conversations be if we called it “surviving outside,” instead of “illegal camping?"
If we are to examine impacts of unhoused people on the environment, it's important to consider how we approach it. Do we consider the impacts by the whole community? Have we considered the cycles of the ecosystems in which they occur? Have we checked our assumptions and cultural biases? To apply science with a confirmation bias would not be good science. And more importantly, actions based on such results might lead to unintentional harm. Before we continue to try to quantify environmental impacts from our unhoused community, we might pause and ask, “Where are we coming from?”
We share these ideas in hopes that our conversations become richer and more meaningful. Let’s continue this discussion together as partners of The Intertwine Alliance. There is so much more to learn from the many voices in our community.