On Stream Health

Nov 29, 2017

Author: Mark Beardsley

Can streams be healthy?  Can they be unhealthy?  If so what does this mean?  By streams, of course, we are talking about places with flowing water.  Rivers and Creeks and things like that.  Naturally, we include riparian areas when speaking of stream health because channels and riparian zones are integrated systems that do not function independently.  We think we know what health means when talking about people.  Is it the same for streams?   Pretty close, I think.  Medical definitions of health include the ability of an organism or one of its parts to perform its vital functions normally or properly; anatomic, physiologic, and psychological integrity; ability to perform valued roles; ability to deal with stress.  These traits apply to streams and other ecosystems as well.  Like people, they are complex systems (eco-systems) whose ability to function, to perform valuable roles, and to deal with stress (that is, to be resilient) depends on their structural, chemical, and biological integrity.

Photo of a healthy stream from Peter Skidmore’s presentation.

At this year’s Sustaining Colorado Watersheds Conference, two smart river scientists named Peter presented two quite different views of what stream health means. Mr. Peter Skidmore showed us pictures of wild, messy, and perhaps even quite unstable streams as examples of healthy ones. What makes them healthy, I think he would say, is that they are natural.  Their parts are intact, integrated, and functioning together with the way they naturally evolved.  No one has really messed with them.  In his own words: “A healthy river is one that supports a full complement of native aquatic and riparian species, with a minimum of human intervention.”   Stream health is a very real thing, independent of humans and our needs and wants.  Stream ecosystems function better when all their hydrological, geological, chemical, and biological parts intact and integrate the way they evolved.  A functional stream is a healthy stream, and a healthy stream is a natural stream.

Dr. Peter Wilcock presented a different idea: that stream health, or at least the goal of improving and preserving streams, is based on human terms.  A healthy stream is one that effectively provides services desired by society.  This view considers the stream ecosystem as a resource, something that can be used to fulfill human needs and desires.  To be a healthy, functioning, and most native aquatic and riparian ecosystem matters little unless that can be translated to human use.  The important question about a stream, he says, is what services does it provide?

I’m not sure Peter Wilcock was really trying to deliver such an extreme message.  I think his main point was that we, as stream restorationists and preservationists, shouldn’t be so flippant with our goals.  We can’t expect society to bend over backward or shower us with funds simply to “make the river healthier.”  People want to know what’s in it for them.  I believe that.  It’s good advice.  But saying that all (stream health) goals are “what people want, and not an expert opinion on what an ecosystem needs” is going way too far.  Social benefits, appearance, comfort, and safety are indeed huge, but that is no reason to quit trying to keep streams as healthy and natural as possible.  Let’s not confuse stream restoration with stream exploitation, stabilization, and enhancement.

Part of Peter Wilcock’s rationale is that people don’t like ecosystem experts telling them how to treat their streams.  I totally get that.  It usually pains me to hear my doctor’s advice, and I often ignore it, especially when he tells me to cut back on the beer-drinking.  But I understand the importance of staying healthy, and I realize that drinking less beer would probably make me healthier and more functional—though certainly less happy.  Like doctors, stream and riparian scientists must speak up about how human actions affect stream health, at least to the extent that we understand how these systems work, but whether or not people follow that advice is up to them.  I am perfectly free to keep polluting myself with beer, thank goodness, and we are free to manipulate streams as we like.  But these actions have health consequences.  Sometimes the immediate goals of society align with stream health.  Sometimes they don’t.

Peter Wilcock talked about the people of a Midwest city who enjoy dying their river green for Saint Patty’s Day.  He says he’s all for that, and I think I am too.  I’m all for having a little fun, as long as no one gets hurt.  I mean it’s a little weird—kind of like when your teenage daughter wants to dye her hair green—but it’s probably not a serious health issue.  In a slightly more serious example, he considered the benefits of a streamside bike path that is “high and dry” rather “than low and wet,” making the case that most people prefer a stream with banks that are high and dry, especially mothers pushing baby strollers and people walking dogs.  Assuming that low and wet is the natural condition and that a high and dry recreation trail would involve clearing riparian vegetation and filling and armoring part of the channel and floodplain, we must understand that meeting these societal preferences involves some sacrifice to stream health.  He analyzed the situation using monetary figures to show how much people would be willing to pay.  Is there not something more at stake here than dollars and cents?

Those examples were easy.  Want to skip right to one of the hard ones?  OK.  Dams.  People like lakes.  Walleye fishermen and waterskiers sure do.  So do the farmers who need water in the summer to grow food, and so do the city folk who appreciate water flowing through their faucets yearlong.  Surely no one would say that drowning a river under a reservoir is good for its health, not to mention the hydraulic, geomorphic, physicochemical, and biologic impacts of a dam for miles and miles downstream.  When the big dams went in on the Green River in the late 1950s, many river biologists praised how it would release cold, clear, sediment-free water and transform miles of warm silty desert river into a world-class trout fishery.  They must not have realized that just a few decades later other biologists would be left trying to figure out how to save the native species that can no longer live there and are on the path to extinction.

In many cases, dams and other big water projects are necessary and valuable.  To use Peter Wilcock’s words, they provide social benefits, aesthetics, comfort, and safety.  People want them.  But that doesn’t mean they have no impact on the health of the stream and riparian ecosystems, and it doesn’t mean that there won’t be value lost.  It all may figure positively in terms of dollars and cents, but let’s not ignore what stream and riparian scientists have to say about it.

18th-century philosopher and ethicist, Immanuel Kant, said that the value of a thing stems from either price or dignity.  The value of commodities and resources is tied to price.  They can be bought, sold, and exchanged freely.  We value people, on the other hand, their dignity.  I would not have remembered this from my college philosophy class were it not for Dr. Colin Thorne who, along with the two Peters, is another one of my river heroes.  Dr. Thorne recently cited Immanuel Kant in a plea to consider the dignity of rivers.  Not everything about streams and other ecosystems can be reduced to price, he would say.  They are not mere commodities.  Stream and riparian ecosystems have dignity.

My favorite environmental philosopher, Holmes Rolston III, describes three types of value.   Instrumental value comes from direct benefits to humans and society.  It is value for the price of service to society, as Peter Wilcock might put it.  Intrinsic value is value in and of itself.  It comes from dignity—a respect for life.  Of course, people have this, and so do other living things.  Do streams have intrinsic value over and above any instrumental value from the services they provide us?  I think yes.  The third cardinal value, systemic value, comes from respect for the ecosystems that produce and sustain life.  Whatever people do to make efficient use of natural resources, and whatever we make of our cultures, anthropocentric preferences, and duties to society and other people; we owe something to the beauty, integrity, and persistence of the systems that produce and sustain life on earth, including us.  Shouldn’t we factor the systemic value of stream and riparian ecosystems into the discussion, at least on some level?

Aldo Leopold would say we should.  The 19th-century biologist and philosopher lamented that nature had previously been appreciated only for its instrumental value to people.  He aimed to change all that in a powerful argument for the Land Ethic, which is classically summarized in two short sentences:  “A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise.”  That is not to say that ecosystem health trumps human instrumental values, but it is another factor we ought to consider when making decisions about how to manage the land, including our stream and riparian ecosystems.

If all this philosophy is too much for some of you, then let’s be practical.  You don’t have to give a hoot about dignity or the intrinsic or systemic values of nature to care about stream health.  It can be all about humility and prudence.  We are resourceful engineers with an abundance of tools and a desire to use them. One thing we are certainly good at is manipulating streams to our benefit.  If we want them to be straighter, we straighten them.  If we want them to stop moving around, we armor their banks.  If we want them to stop flowing, we dams them.  If we need their water somewhere else, we take it.  If we want more and bigger trout, or more ducks, or more anything, we can usually do that too.  We have lots of levers we can pull and lots of parts we can rearrange to make these systems look and behave the way we want.  But do we really know all the effects of these clever manipulations?  Stream systems are rich and extremely complex, despite the ease with which we manipulate them.  A little humility and a healthy respect for their richness and complexity—a respect for stream health—is in order, even if our sole aim is to make them work for us.  As Aldo Leopold himself said, “to keep every cog and wheel is the first precaution of intelligent tinkering”. 

One of the most cited papers in stream science is LeRoy Poff et al.‘s “The Natural Flow Regime.”  There is a lot of great stuff in that paper, but when you boil it down it basically says that the optimal flow regime for stream health, the one that supports socially valued native species and provides important goods and services to society, is, well, the natural one.  When we manipulate flows, even with the best intentions, there are implications to other aspects of stream health and usually a net loss of total function.  The same is probably true for other aspects of stream health:  The most functional geomorphic regime is probably the natural one.  The best chemical condition is probably the one that occurs naturally.  And the best biotic structure is probably the suite of native species that evolved in nature.  As we manipulate these components to maximize specific social benefits and services, we need to keep in mind the incremental and cumulative effects on stream health if we want to keep these systems sustainable and functional into the future.

I think this might be what Peter Skidmore was getting at.  Streams can be healthy or unhealthy.  In most cases, the more natural a stream is, the healthier it is, the better it functions, and the more it serves our needs.  We can alter streams to meet specific goals, but we must consider these actions in terms of stream health and not just cost, if not for the moral reasons (intrinsic and systemic value) then as a simple matter of humility and prudence.  We can continue dyeing rivers, we can raise and armor banks to make high and dry trails, and we can dam rivers to make lakes and satisfy our thirst.  We can pretty much exploit, stabilize, and enhance streams to our hearts’ content, but let’s not get in the habit of pretending that these improvements don’t impact their health.


Colorado Riparian Association