# Does trail erosion really harm the environment?



## TwoHeadsBrewing (Aug 28, 2009)

I'm interested in learning about how much environmental impact is caused by trails, both properly and improperly built. It seems that many people talk about erosion, damage, environmental impact, habitat destruction, etc. as to how it relates to mountain biking. I wonder what studies have concluded that biking, hiking, horseback riding, etc. has shown that there is real and lasting damage from these uses. Is it just a commonly accepted notion, or is it based in evidence? And I'm also interested in opinions as well as links for formal studies on the subject.

How much soil is produced from runoff on different types of trails? Is there any runoff at all in meadow or boggy areas, and what other impacts might there be? What, if any, are the long term effects of erosion? How long would a trail last if closed off and abandoned entirely? 

How does one categorize the different levels of erosion? It's a natural process, but certainly there are acceptable amounts of soil movement, and then other amounts far exceed natural processes. How much of erosion is just unsightly versus damaging to the environment? How does one assess that damage or evaluate the cost of it? 

And of course the ultimate question: Do trails (hiking or biking) do significant damage to the environment?


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## thefriar (Jan 23, 2008)

Many answers to your questions here: Environmental Impacts of Mountain Biking: Science Review and Best Practices | International Mountain Bicycling Association

Poorly built trails can dump tons of sediment down stream and cause serious issues, mismanaged trails can lead to massive erosion (think of a good/well built trail that was made for only 10-30 users a day that now gets 200-300) and cause serious issues.

I've seen Aerials for 20 years ago, 10 years, and then 2 years for same park that sits adjactent/borders a several mile stretch of river. The trails have become extremely popular in the past 4 years or so with a multitude of user groups, they were never "sustainably" designed or built but didn't have issues at the 20 and 10 year marks... now you can see the sediment build up in the aerials plus observable river/stream depths below the park have become much more shallow... no upstream impacts.

To be fair, most of the increase in use is from dog walkers vs. bikers or hikers so there are addition, off trail impacts at play. But none-the-less if the trail system was designed for volume and user type the erosion and impacts wouldn't be anywhere near where they are. (we have another park on another river not far away with steady use levels over the past 10-20 years and there are negligible impacts, albeit many fewer total users...)


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## Harold (Dec 23, 2003)

First off, "erosion" is the degradation of the trail or hillside itself, but the process occurring that causes it would be sedimentation, or the transportation of sediment by wind, water, and other mechanical means.

Any bare soil surface is going to have higher sedimentation rates than a vegetated surface. Higher slope will have faster water movement, which is capable of moving larger soil particles farther and faster. Increased sediment in streams and lakes reduces light transmission, smothers aquatic vegetation, and results in reduced oxygenation for fish and invertebrates. Certain nutrients like phosphorus and many contaminants adhere to soil particles and are transported into waterways on those sediment particles.

Then there's the simple mechanical properties of increased sediment load in waterways. It fills and narrows stream channels, cutting the waterway off from its floodplains. It fills reservoirs, reducing capacity for floodwaters and drinking waters (and thereby necessitating more frequent dredging to maintain the reservoir). The filling of lakes and reservoirs is problematic because it raises the bottom of the waterbody, permitting more floating and emergent vegetation to grow in the waterbody. When that vegetation dies, it sinks to the bottom, consuming already sparse oxygen in its decaying process, and causes that waterbody to fill more quickly with incompletely decayed plant matter, that generates more methane. This process is called eutrophication, and is exacerbated by fertilizer runoff.

Yes, this process occurs all the time, everywhere, already. The process is heavily documented and can be measured. Poorly built trails can add significantly to the sediment load in surface water runoff. Well built trails will add to the process, also, but somewhat less so. Where I live, land managers have been phasing out regular stream crossings in favor of bridges because stream crossings are something that directly and rapidly affect stream sedimentation. You ride through a flowing stream and you immediately stir up sediment that has effects downstream from the crossing.

Your final question is a little too emotionally loaded and subjective. Yes, the mere existence of trails results in rippling effects through the environment. The word "damage" connotes that there is an aesthetic component to those effects. In some cases, there absolutely is an aesthetic effect. We know intuitively based on our experiences on many different trails that some trails erode heavily over the years and get deeply channeled. That displaced sediment has to go somewhere, and usually the sediment we see collected at the bottom of the slope does not account for all the sediment that used to be on the trail. It is better to quantify the degree of effect that is excessive or unacceptable to the land manager.

Right now, it would be too expensive to go out to many different locations before and after a trail is built to measure sedimentation, soil loss, and soil compaction to really come up with conclusions in absolutes.

But what we do know is that IMBA has developed its recommentations for trail tread slope, inslope, and outslope to minimize erosion based on the results of studies that they try to link to (not all are available). Those recommendations obviously change for different soil types and when armored or stabilized trails are thrown into the mix. So what happens is that the apparent erosion of the trail tread is used as a gauge to indicate how much sedimentation is being caused by a particular trail. If the trail tread is not becoming obviously eroded over time, then sedimentation from that trail is minimal and it's not a problem. If, however, the trail is visibly eroded, a land manager can easily decide that it's excessive and enact closures. That part is mostly done based on aesthetics. You could go out with a measuring device and quantify soil loss at specified intervals if you really wanted to invest that kind of time and money into it. The occasional scientist interested in the particulars might go and do that. But the land manager is going to look at it and decide if it's eroding visibly or not and decide from there.

The way users interact with the trail will also make a difference here. Users who use the trail heavily during sensitive times are going to have a greater impact than users who maximize their use during optimal times and avoid the trail when it's sensitive. Whether that occurs in the wet season when there's a lot of mud that sticks to tires and boots (and gets carried away or pushed aside to channel water) or during the dry season when heavy use creates dust that blows away is not really all that important.

Relative to your question about meadow or boggy areas, different processes occur in flat areas with low or minimal surface runoff, which is the primary way that most trail erosion occurs. It's going to be very climate dependent. In a meadow or prairie type situation, the soil is typically held in place by the roots of grasses and forbs. When you have a trail that passes through such a landscape, soil compaction is going to prevent root growth under the trail. That soil compaction will result in a u-shaped channel where the trail passes through. That u-shaped channel will now act as a funnel for water, which will now cause sedimentation and cause soil loss if the slope is great enough for that water to flow downhill. If not, then the water will just sit there and create mud pits because the compacted soil now serves as a hardpan preventing infiltration. Trail users walk around said mud pits, making the compacted zone wider and the pits bigger and they will ride through them, churning up the mud at the bottom and displacing soil, making the pit deeper. This kind of thing needs to be patched and the trail tread raised or bridged so water flows off of the trail tread. Rock can be used to armor the location, too, and water will either flow off or infiltrate between the rocks.

In boggy areas, boots and tires are just churning up mud, moving it around, and creating ever deeper pits and channels. This is why people either avoid such areas entirely or build bridges over them.


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## TwoHeadsBrewing (Aug 28, 2009)

Thanks for the reference! I wonder about the soil erosion into the streams, and how much there has to be in order to negatively effect wildlife. It seems like this is potentially the largest potential for quantitative "damage" from trails.

Obviously, a certain amount or erosion could be beneficial or at least tolerated by wildlife. Erosion is widely variable year to year, so wildlife already have a certain level of tolerance to it. So at what point could levels of soil erosion be deemed "excessive"? And how much soil is a trail 1-2ft wide and say 5 miles long capable of depositing in any one watershed area over a years time? How much of the erosion on the trail actually makes it to a nearby stream vs. just being deposited with a few feet and nurturing vegetation growth?


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## TwoHeadsBrewing (Aug 28, 2009)

Great input NateHawk, thank you. Just out of curiosity, do you work or study in a related field?


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## Harold (Dec 23, 2003)

it depends. too many variables to make blanket statements about it. What's the slope? how big is the watershed? What is the soil type on the trail? What kind of vegetation grows around the trail? What's the rainfall? How much of a factor is wind (see vegetation question)? What are the characteristics of the water bodies downstream? Flow speed, flow volume, corridor width, stream slope, lake depth, adjacent wetland storage capacity? What plants and animals currently live in the water bodies? What are the various land uses in the watershed? upstream of the trails? downstream of the trails? What soil particle sizes are being transported into the water? Are there additional nutrients or contaminants adhered to them? How do they behave when they reach the water? Are they small enough to be suspended? Are they heavy enough that they collect nearby? What is the stream substrate already? Is it very rocky, is it gravelly, or is it silty? What is the water oxygenation already? What nutrients are already in the water and what are their levels? How to those levels stand to be impacted from the sediment particles being transported into the water?

You have to answer those questions and more in order to reach the answers to the questions you have.

In one place I lived a number of years ago, the trails were built in a park around a small reservoir built for floodwater retention, and used currently mostly for recreation. A construction project upstream of the park dumped FAR more sediment into the reservoir (affecting the biotic community) and resulted in its needing dredged than years upon years of erosion from the mostly mediocre but occasionally crappy trails in the park that occurred in a landscape with fairly steep slopes, somewhat high annual rainfall, and clayey soil with a high rock content (which limited sediment transportation in all but the worst trail segments).


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## Harold (Dec 23, 2003)

TwoHeadsBrewing said:


> Great input NateHawk, thank you. Just out of curiosity, do you work or study in a related field?


MS in Environmental Science


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## formica (Jul 4, 2004)

TwoHeadsBrewing said:


> Thanks for the reference! I wonder about the soil erosion into the streams, and how much there has to be in order to negatively effect wildlife. It seems like this is potentially the largest potential for quantitative "damage" from trails.
> 
> Obviously, a certain amount or erosion could be beneficial or at least tolerated by wildlife. Erosion is widely variable year to year, so wildlife already have a certain level of tolerance to it. So at what point could levels of soil erosion be deemed "excessive"? And how much soil is a trail 1-2ft wide and say 5 miles long capable of depositing in any one watershed area over a years time? How much of the erosion on the trail actually makes it to a nearby stream vs. just being deposited with a few feet and nurturing vegetation growth?


That is all going to depend on your soil/subsoil composition, amount of and types of precipitation and other erosive factors. Sands, clays and loam all weather, degrade and move at different rates. Freeze/thaw cycles, annual rainfall, how the rainfall is distributed ( ie, downpour and heavy rain vs consistent light moisture), weathering rates of the different minerals in the soil/subsoil.... all of that is going to vary a huge amount from region to region so I don't know that there is a general way to quantify it.


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## TwoHeadsBrewing (Aug 28, 2009)

I agree that there are many different factors. So just to be specific, here is the area I'm looking at:

Bidwell Park in Chico, CA. Specifically, the "Upper Park" area is the one with the most trails and mountain biking use. It is essentially a canyon that has trails both on the north and south sides, plus trails running parallel to the stream or canyon walls. Soil type on top of the canyon is sandy and thin with exposed lava cap in places. Soil type in the areas closer to the steam have a significant amount of clay in them, are are more substantial. Vegetation is mostly wild grasses, poison oak, valley or scrub oak, buckbrush, manzanita and Ponderosa pine. Rainfall is seasonal and heavy January-April, and very dry in the remaining months.

Here's a few pictures, and a map of the area:
Road that runs down the center of Upper Park: Bidwell Map - A bike ride in Chico, CA
Bike map of Upper and Lower park: http://www.bidwellpark.org/page/_files/UpperLowerParkMap.pdf

Thin soil on top of the North Rim Trail, which is heavily eroded by previous use as a Jeep trail before the 1970s, and recreational hiking/biking/horse use since then:









From the South Rim Trail looking towards North Rim, taken just a few weeks ago:









Same spot, different bike but in the middle of summer. Looking West and downhill:









Spring time, on one of the lower trails a few hundred yards from the stream which is in a steep canyon. 









Lovejoy Basalt is what makes up the formation at stream level. Very little sediment at the bottom, mostly rock and gravel, probably due to being confined in a relatively narrow corridor by the rocks.


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## Ridnparadise (Dec 14, 2007)

With the average LM starting to look further into the future, it is a really good question. There are places where trails have existed for hundreds if not thousands of years with limited impact. Considering the number of users and escalation over time, even rocky trails (eg European Alps) may become a problem in the future. I wonder how long before soil traps will become part of the construction technique for rolling grade dips and drains?


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## evasive (Feb 18, 2005)

Good question. I'm glad someone asked it, because it's something I think about in some of these threads, and it's interesting to read others' take on it. NateHawk gave you a good summary of the processes and issues related to erosion and sedimentation. 

In my view, sediment that doesn't make it to the stream isn't much of a problem. It's when it's in the stream that it causes habitat issues, generally related to fisheries and macroinvertebrates. I'm not suggesting that trail erosion isn't an issue, because it is, but it's separate, although related. I consider that more of an infrastructure and stewardship problem than an environmental problem. Modern trail design generally calls for outsloped trails with grade sufficiently less than the side hill so that water doesn't get channelized and concentrated, but instead runs as sheetflow across the trail. The amount of sediment generated by these trails is minimal. That's a concept I wish I could explain to some local bonehead who keeps digging enormous drainage ditches across our trails, oriented along the fall line. He's creating drainage problems where none existed. Sigh. Legacy or unauthorized trails tend to have fall-line pitches that can really erode, and move some water. One of my favorite trails near here is a CCC-era USFS trail. Old school. I was fixing a flat on it last may, racing a thunderstorm. My camera fell out of my bag without me noticing. I went back for it the next day, and it was about 150 yards down the trail from where I had been stopped. Recently eroded and deposited sediment was obvious all over the place. But it was mostly limited the the trail corridor. 

So how much sediment makes it to the stream? As NateHawk aptly illustrated, it depends on a lot of variables. But in general, if we're talking about upland trails and not stream crossings, not that much.

I used to be a geologist. I did my MS fieldwork in Northern CA (Yreka-Callahan area) and I've spent a little time in the Chico area, too. Nowadays I'm a watershed planner. I work on TMDLs, which are basically the allowable loading rates for how much of a pollutant (e.g. copper, zinc, nitrogen, sediment, temperature) a stream or lake can take before it's impaired. I do a lot of work to model the sediment loads coming from unpaved road networks. So does the USFS; in fact I usually use their model. There are also a lot of field-based quantitative studies of these issues that we use as checks, and we do our own surveys of representative samples. The amount of sediment that an eroding road can generate is pretty amazing. It's also impressive how much some basic BMPs (best management practices) can reduce that. And more to the point, a healthy vegetated buffer can trap an amazing amount of sediment. I've spent a lot of time quantifying the amount of sediment shed off unpaved roads and the amount that makes it to a stream through a buffer. That's why I think the impact of upland trails is pretty small. 

Stream crossings, however, are bad news. Usually the trail (or road) is incised and heads straight across the stream as it drops down the bank, so the runoff is focused and directed straight into the channel. More bridges or engineered crossings is a good thing in most cases, although a lot of crossings are poorly designed and cause stream channel issues. This is admittedly less of an issue with trails than with roads, however. 

I should qualify that all of that is written from the perspective of western Montana. Our climate, land use and environmental issues aren't universal.


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## ABud (Feb 12, 2012)

Where would New Orleans be without the Mississippi Delta. I Love that Town.


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## Ridnparadise (Dec 14, 2007)

evasive said:


> And more to the point, a healthy vegetated buffer can trap an amazing amount of sediment. I've spent a lot of time quantifying the amount of sediment shed off unpaved roads and the amount that makes it to a stream through a buffer. That's why I think the impact of upland trails is pretty small.


This thread is bringing up some good stuff. I am going to try to connect what sound like opposites: a vegetation buffer and an excessive footprint made during trail construction, as related to to erosion and sediment.

We had an on-site meeting with our local senior ranger yesterday. We had been working there only three days earlier and the visual impact of the work was maximal, but we suggested going there for a chat. In the following pics, a larger visual corridor is obvious after the work, as is debris over the vegetation and drainage lines nearby.







































After the ranger left we completed the section of work with a new trail line and rolling grade dip past the top of these pics... but the point is, we work in a National Park. Erosion and footprint are important. From the pics you can see the loss of some vegetation barrier.

The existing trails in the park are narrow and techy. The deal is we restore trails to standard to make them legal and often that means wider; a threat to the rangers in itself. Riders are also not all fans of wider trail. "Dumbed-down" - you've heard it.

We have transplanted grasses as part of our works through all the wet periods (we have received an average of > 10mm daily since New Year) and they certainly regrow. However, we also make trail wider than it will end up.

Riders pick the best line to ride. It is easier to do that when you can see ahead, so wider trail almost always means better sight lines. What starts wide, narrows as it hardens, but vegetation reclaims the edges of the trail not ridden. What does not happen is riders catching cranks on logs and rocks hidden under re-growth.

We don't work in a dry environment, but here, making drainages and corridor larger initially seems to lessen the overall movement of surface soil in the longer run by riders selecting a narrower line with a more established vegetation buffer. Any thoughts?


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## evasive (Feb 18, 2005)

Well, the buffer traps sediment leaving the trail corridor. When I think of a buffer, what I'm thinking of is the distance between a trail or road and a stream. Diffuse sediment transported by sheet flow generally doesn't go too far through vegetation. What you want to avoid are situations where you create channelized flow, which will move a lot of water and sediment, and erode your trail in the process.

It definitely looks like you had some erosion issues going on. Speaking for myself, I'm OK with wider if it affords options, and better sightlines are pretty much never bad.

I can't see the whole situation in your trail example, but it looks like the third picture is the same view as the first, taken after the work? It looks like there's still some channelized flow cutting across the trail, and that will probably continue to be a problem for you. It looks like the ditch alongside the trail has been filled in and armored, but since it's on the upslope side of the trail, my guess is that it will intercept runoff and shallow groundwater from the slope above and send it along the ditch until it dumps out across the trail.

The key thing to remember is that you want contributing lengths (i.e. the length of trail that will send water along the trail, rather than across) to be as short as possible. For my work in roads, that's the key factor that drives how much sediment is eroded from the road/trail surface. The longer that length, the greater your chances of channelizing the flow. As I mentioned, my perspective is not exactly that of a trailbuilder. Someone who has more shovel experience with trails had better take it from here.


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## TwoHeadsBrewing (Aug 28, 2009)

Great input here, thank you to all the people for sharing knowledge about erosion-related issues. I'm going to get up into the park at some point this weekend and take a few pictures of problem areas.


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## Harold (Dec 23, 2003)

evasive said:


> Well, the buffer traps sediment leaving the trail corridor. When I think of a buffer, what I'm thinking of is the distance between a trail or road and a stream. Diffuse sediment transported by sheet flow generally doesn't go too far through vegetation. What you want to avoid are situations where you create channelized flow, which will move a lot of water and sediment, and erode your trail in the process.
> 
> It definitely looks like you had some erosion issues going on. Speaking for myself, I'm OK with wider if it affords options, and better sightlines are pretty much never bad.
> 
> ...


The mechanics are the same with trails. frequent grade reversals on trails accomplish the same thing as having short "contributing lengths" in your work sense.

I'd not be terribly confident with the long-term prospects of the patches in the pics above. While filling the channel is important, the type of fill used here will allow water to move within the fill, so some soil erosion would still be expected to occur underneath the coarse rock unless extensive efforts were taken to keep water out of the channel in the first place, and to get it out of the channel once it got there. I think mixing a finer fill along with the coarse fill would help to keep water out of the channel, and allow the material to pack down well. Deberming the downslope side and/or filling the upslope side would encourage more sheet flow off the side of the trail and discourage channelizing. Finally, I'd have added rolling grade dips within the pictured area OR routed the trail slightly up or downslope to add another grade reversal within the pictured area.

Grasses are probably some of the most ideal buffer plants. They have a lot of very fibrous roots that hold sediment well. Better than plants with less dense root systems or a taproot. They also have a very high stem density, which helps to trap sediment. Perennial grasses are also quite durable and you can choose species better adapted to high moisture, low moisture, rich soils, poor soils, essentially whatever conditions you have to work with. Furthermore, using native plants in your restorations makes land managers happy.


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## Ridnparadise (Dec 14, 2007)

Look, sorry I did not not post those pics as an example of the work we did there, more just to open dialogue on buffers and wider trail lines. Seeing the issues of that site have been raised, what you cannot see is a 90 degree and very steep turn to the left at the top of that section of trail. It runs the trail back, parallel to the top of a seasonal, steep and narrow creek line that starts with a fire road drainage. Water flows at high speed and in great quantity down the creek line and down the falline section of trail past that 90 degree corner. 

Since those pics there is a new rolling grade dip beyond the stones in the upslope drain. They were only put there as a temporary meaure to slow water flow until we added the next drainage and to encourage a new riding line away from exposed roots also on the upslope of the trail edge. Water will now only get into that section of drainage if it sheets off the slope above the trail and then will move towards the drainage in the foreground of that pic. That is also a rolling grade dip armoured with embedded stone and will be more than durable enough to cope with any flow coming off about 8-10m of trail. 

What is also not clear in the pics is that the creek crossing the trail will also be turned into a substantial drain to remove water flowing from the steep corner as well as from the creek itself. In addition, there is a complete re-route of the old trail (about 2km long) that starts out of picture to the right at the end of that bit we have changed in the pics. So don't worry too much about what will happen to the work shown, as it has already been changed in line with your recommendations and will be diverted to the new trail when it is opened. That new trail covers the total distance without turning back across the falline, removing many falline and switchback sections of old trail.


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## sambs827 (Dec 8, 2008)

TwoHeadsBrewing said:


> Lovejoy Basalt is what makes up the formation at stream level. Very little sediment at the bottom, mostly rock and gravel, probably due to being confined in a relatively narrow corridor by the rocks.


To be fair, rock and gravel are both sediment. Anything that's not part of the bedrock can be lumped into the group of "sediment" and can certainly be moved. The only reason you're not seeing pea gravel/sand/silt/clay here is because it's been carried away by that stream. As someone else already mentioned, the sediment load at the bottom of the hill doesn't necessarily account for all the sediment eroded from the slope. All of that smaller sediment has been carried out of the system.

Not exactly an answer to your question, but related: Up until the past couple hundred years, water was the erosive agent responsible for the largest amount of sediment worldwide. Now humans are. Spooky.


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## Berkeley Mike (Jan 13, 2004)

Great presentation Natehawk. Much appreciated.


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## UncleTrail (Sep 29, 2007)

Interesting thread. Could I ask you to step back and take a look at the bigger picture though?

I remember several years back building a golf course and having all the hillsides exposed without vegetation after the belly scrapers came through and shaped everything. A freak storm rolled in and we ended up with 25 feet vertical of silt in our irrigation pond, which sat at the bottom of a gully.

Now think about a forest fire, or a grass fire, or Wildfire. And you end up with hundreds of thousands of acres of exposed soil with nothing holding it together, sitting there and just waiting for a big storm to wash it down the hill and into every stream. That impacts wildlife. Doesn't it? 

Wildfires happen every year. In many areas where we have trails, wildfires are controlled, by humans... so to be honest with yourself, I think you have to wonder if perhaps, the pristine "natural" environment we ride through, isn't in fact... artificial, man-made and controlled by man.

So who is really to say if by allowing "some" sedimentation to occur by the use of and construction of trails, that we are really doing any more damage that would naturally have occurred due to Mother Nature's fires/floods?

Just build smart. Use the 1/2 rule. Use the lay of the land. And then remind the people who tell you that trail cause erosion, that fires do to.


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## Harold (Dec 23, 2003)

The big difference between a landscape burned by a fire and a trail is a matter of time scale. A burned area can begin revegetating within weeks in some cases. That trail persists on the landscape for years...sometimes decades or centuries.

Yeah construction projects generate magnitudes more problems in a short period of time. But making such comparisons is not really relevant to this discussion. It is about trail erosion issues, not activites that negatively affect wildlife. Perspective matters. pretending that the effects of trails are insignificant is folly.


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## ABud (Feb 12, 2012)

UncleTrail you are correct, build responsibly and don't sweat the small stuff. I believe people get carried away with erosion and sustainability of mountain bike trails. As I have said before most trails are not self sustaining, if it's broke fix it. Every now and then you will get an unusually heavy rain and your trail may blow out but this will be a small part of total area wide erosion, look in the river it's brown and not from your mountain bike trail. The repair above looks great to me the water is off the trail the consequential erosion is immeasurable. Job well done.


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## UncleTrail (Sep 29, 2007)

NateHawk said:


> The big difference between a landscape burned by a fire and a trail is a matter of time scale. A burned area can begin revegetating within weeks in some cases. That trail persists on the landscape for years...sometimes decades or centuries.


But it only takes one rainstorm to wash everything down the hill. And that happens more frequently than we may be aware of as laymen.

I've been making soil burn maps for last last summers Waldo Canyon fire and we're looking at 10 years before some areas are established enough to prevent erosion and increased sedimentation into our stormwater infrastructure. That's 10 years of increased sedimentation coming down Fountain Creek, with fish, wildlife, etc... being impacted. The sedimentation loads are pretty heavy for over 1/2"/hr rainfall events. That's not very much rain. We've just been lucky thus far, but now we're going into Spring...

We've also just had some of our best trails closed permanently because of the "lost but found" only living population of greenback cutthroat trout in Bear Creek.

Why do I bring this up?
Last year the Center for Biological Diversity sued the USFS over motos riding up and down a trail adjacent to the creek the trout live in and some study, the CBD paid for, said that motos were causing sedimentation of Bear Creek. Nevermind that the fish were stocked in Bear Creek by a Broadmoor Hotel caretaker around 1900 and that Bear Creek is not their native habitat, they were put there to increase fishing opportunities for Broadmoor guests. It's a fish living in a non-native habitat, just like a weed put there by man. It's non-native.

Yet the trail was just closed to everyone, not just motos.

The Waldo fire was only stopped by a highway from entering what is called the South Slope Watershed, which includes Bear Creek and its' trout. We (humans) saved those fish, again. To think that some dirt from a trail is going to kill those fish when they have survived forest fires, wagon trains, mining, etc... is somewhat amusing... were it not for the fact that people who can't put things into perspective decided to shut my favorite trails down for good.

The greenback cutthroat trout surviving once again because of man, while man is being told he is the reason they are dying, is somewhat ironic.


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## Harold (Dec 23, 2003)

Look man, this isn't about your specific case though it does address some of the issues being discussed here. Frankly, it doesn't matter if the fish is not native to the last place it is currently found. Gov't agencies are tasked with protecting species along with the other things they do. Especially the USFS.

There are a lot of groups out there that do little other than sue government agencies. Sometimes the cases are valid and sometimes they are BS. Sometimes there is no clear answer and someone is bound to lose out.

The only thing I know about your situation is that trout require high oxygenation and are therefore particularly sensitive to a drop in oxygenation. When there are negative impacts, trout will be some of the first species to feel the hurt from it.

I have no idea about the validity of the research the CBD sponsored. But the fact that there was research at all suggests that there were some very smart people involved. If you have a link it would be appreciated.

It still doesn't change the fact that trails do result in increased sedimentation. It does not change the effects of sediment on aquatic communities. As a biologist, I think an endangered species takes precedence over a trail. Maybe outright closure was a lazy response to the situation. But I'm sure that efforts to keep the trails open while balancing the requirement to protect the fish would have pissed people off, also.


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## Ridnparadise (Dec 14, 2007)

NateHawk said:


> Look man, this isn't about your specific case though it does address some of the issues being discussed here. Frankly, it doesn't matter if the fish is not native to the last place it is currently found. Gov't agencies are tasked with protecting species along with the other things they do. Especially the USFS.
> 
> There are a lot of groups out there that do little other than sue government agencies. Sometimes the cases are valid and sometimes they are BS. Sometimes there is no clear answer and someone is bound to lose out.
> 
> ...


I think UT was using one example to demonstrate the conflict this thread intended we discuss, NateHawk. The question that I see when I read your responses, is where do you draw the line between environment more important, versus man more important? Take that further - where is that line when there is historical evidence of man accessing "the" place in question?

That little bit of work I posted above is fairly typical of most trails. It has a footprint for sure, but how big? It is in a National Park and was made a long time ago when a different LM controlled the site. Lots of people use it and most of them were OK with the trail in the state it was before renovation. After the section is complete, we feel good about long-term sustainability.

It is not going to be a motorway and will not be impervious to nature, riders or riders who don't give a $h!t about trail damaged by nature. So it will be a worry to someone taking NateHawk's pro-environment opinions to the limit. On the other hand; if this trail was closed, they would ride the closures down. If it was "removed", they would build another. They don't help us work on the trails they value, but they will take control of the land they call their own, as in the past if there is no agreement to have MTB in the area.

After riding and making tracks since I was a little kid and spending more available time than I had in the bush, it seems almost stupid to talk about whether a trail has an environmental impact. A fart has an environmental impact - devastating to the microorganisms that leave the host to face the wide world (the sediment). The real question is whether, as a trailbuilder you care about what you leave as your footprint? Whether you will leave and never come back, whether you never change problem areas because you made them to be a certain way, whether you are prepared to see faults as well as success in your work, whether you have resources available to do what you intend... More importantly, do you have a plan to merge the blurred line of people versus environment?


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## Harold (Dec 23, 2003)

Where do I draw the line? That is not a simple question to answer. It really depends on the case specifics. There needs to be a reasonable attempt to balance both sides when there is a conflict but sometimes that may not be possible.


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## TwoHeadsBrewing (Aug 28, 2009)

NateHawk said:


> Where do I draw the line? That is not a simple question to answer. It really depends on the case specifics. There needs to be a reasonable attempt to balance both sides when there is a conflict but sometimes that may not be possible.


I think a great tool for figuring out man-made impact is a before and after study. Unfortunately this is almost impossible to do unless you're building a trail in a previously untouched area. And one snapshot a month or a year before building isn't going to work either, since nature is a dynamic system; always in flux.

I think, like in almost all things, the answer lies somewhere in the middle of the two extremes. Trail building DOES in fact contribute to erosion and more soil and organic matter being deposited in streams and reservoirs. At least in examples I've seen of responsible trail building (not even necessarily correctly built trails), erosion does not contribute enough to create "harm" or "damage" to the environment. But I think that trail builders and advocacy groups need to be careful not to give too much ground to the extreme environmentalist groups. I've seen too many people go along with these arguments that trail building harms the environment, when that cannot be proven in many cases. This just cedes the higher ground to an opponent that wants to prevent access to a certain group of visitors.

I think a better position to start with is that when trails are properly constructed, there is NO harm, even when some erosion is present. There has to be a range of acceptable amounts of erosion where wildlife is not negatively impacted. Erosion is a natural process and variable year to year based on a number of factors. Are there studies performed that have shown that a properly constructed trail contributes no more erosion than a range of naturally occurring events? Or perhaps a study to show even the opposite? If neither of these exists, how does a land manager go about making a decision about supposed environmental impact?


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## UncleTrail (Sep 29, 2007)

NateHawk said:


> Frankly, it doesn't matter if the fish is not native to the last place it is currently found.


I would argue that it most certainly does matter to the native species of that location who must now compete for resources against this newly introduced "endangered" species. That's the problem with taking plants/animals from their native habitat and placing them in new environments. Like weeds, they can thrive in these situations without competition and quickly overtake the habitat. Nutria. Perfect example. That's why beavers are few and far between in Texas. They could not compete with nutria for resources. Nutria breed like rats.



NateHawk said:


> There are a lot of groups out there that do little other than sue government agencies.


The CBD is one of these. In fact, they have been compensated by the Fed Gov with over $20 million in taxpayer funds in the past 10 years, for suing the Fed Gov under the Endangered Species Act. The CBD is almost entirely comprised of attorney's. That's the great thing about suing the Feds under the ESA. You get compensated with taxpayer funds to do it. Some people make a living out of it.



NateHawk said:


> The only thing I know about your situation is that trout require high oxygenation and are therefore particularly sensitive to a drop in oxygenation. When there are negative impacts, trout will be some of the first species to feel the hurt from it.


True. But we can breed fish. And restock them. We've done it already with the Greenback Cutthroat once, to our folly, since we now are being told that all those millions of fish aren't genetically the "right" trout. The Colorado state fish we spent millions restocking, isn't the right fish....
Pure scientific folly that should humble most any scientist. I won't even get into the inbreeding and homogenization of genotypes in an isolated population of 800 trout in a single stream. It's scientific folly, on top of more scientific folly, on top of more... mainly because it's such a complicated subject that pols and lay audiences cannot grasp the comical nature of what we have already done once, and are now doing again.



NateHawk said:


> As a biologist, I think an endangered species takes precedence over a trail.


What about game trails?


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## UncleTrail (Sep 29, 2007)

TwoHeadsBrewing said:


> I think a great tool for figuring out man-made impact is a before and after study. Unfortunately this is almost impossible to do ...... If neither of these exists, how does a land manager go about making a decision about supposed environmental impact?


I agree with almost everything you said. When you start the conversation at "this trail damages the environment" you've already lost the battle.

BTW, politicians usually decide. It's all about PR and public perception. Right and wrong, facts, truth... have little place in the decision making process. In the end politics will decide for the land manager. You win some, you loose some.


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## Harold (Dec 23, 2003)

How far away is the greenback cutthoat's native country? I do not know the species. That makes a huge diff to this situation. Nutria come from an entirely different continent so apply to this situation on an entirely different scale.

But really it comes down to the fact that you are diminshing the very real effects of the presence of trails by making comparisons to much larger and different impacts and other human activities. Yes, those things have effects, also. There is a difference in scale of those impacts, both in geographic extent and temporal extent.

I am not making any absolute statements about whether one is more harmful than another. The answer to that is that it depends on each situation individually.


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## UncleTrail (Sep 29, 2007)

NateHawk said:


> But really it comes down to the fact that you are diminshing
> the very real effects of the presence of trails by making comparisons to much larger and
> different impacts and other human activities.


I am putting things into perspective by looking at the scale of the impacts and forming my own 
opinions based on what I see plus my own experiences out in the real world. I also believe it
would be good for MTB'rs to do the same.

This is what the post-Waldo Canyon fire sedimentation looks like after a single 1" rainfall event. 







InciWeb the Incident Information System: Waldo Canyon Fire Photographs

IMHO there's just no comparison to the damage a little bicycle trail may, or may not have on the environment.


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## thefriar (Jan 23, 2008)

Are you familiar with the term perception is reality? 

If Land Managers perceive us as being as bad as rain/weather/other impacts, then we are regardless of the reality.

If they decide to restrict our access because of such perceptions, then our reality is we can use those trails, and if we do they can pursue various remedies or deterrents to our use. 

That is the reality of the situation at the end of the day regardless of how any one of us MTBers perceives it.


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## Harold (Dec 23, 2003)

UncleTrail said:


> I am putting things into perspective by looking at the scale of the impacts and forming my own
> opinions based on what I see plus my own experiences out in the real world. I also believe it
> would be good for MTB'rs to do the same.
> 
> ...


You aren't getting it. The question was about the impacts of a trail. The question was not about comparing the scale of the impacts of a trail with the scale of impacts from post-fire erosion, or the scale of erosion from a poorly managed construction site (yes, the scale of the impact from a trail is less than the others, but that does not mean it is not or cannot be harmful). The trail has impacts. It is up to the land manager to decide if those impacts are unacceptable based on information they are privy to (and we may or may not be). It is in our best interest to understand what occurs and to minimize erosion when a bit of trail is constructed or maintained to avoid problems with the land manager in the future.


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## TwoHeadsBrewing (Aug 28, 2009)

NateHawk said:


> You aren't getting it. The question was about the impacts of a trail. The question was not about comparing the scale of the impacts of a trail with the scale of impacts from post-fire erosion, or the scale of erosion from a poorly managed construction site (yes, the scale of the impact from a trail is less than the others, but that does not mean it is not or cannot be harmful). The trail has impacts. It is up to the land manager to decide if those impacts are unacceptable based on information they are privy to (and we may or may not be). It is in our best interest to understand what occurs and to minimize erosion when a bit of trail is constructed or maintained to avoid problems with the land manager in the future.


I think it's important in discussions with the land managers and owners to bring up both sides of the issue. On one hand, there IS indeed erosion from trails which may or may not harm wildlife habitat based on a variety of factors. On the other hand, it's important to note that erosion from both trail construction and normal use and maintenance is very likely to be insignificant. I think often in government the squeaky wheel gets the grease. That squeaky wheel is often ultra environmentalist-type groups that see any type of human involvement as a bad thing. At least, that's the case around here.

I'm hoping through education and sharing actual data from scientific surveys that the land managers will have some better tools to aid in their decision making.


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## Fattirewilly (Dec 10, 2001)

NateHawk said:


> In one place I lived a number of years ago, the trails were built in a park around a small reservoir built for floodwater retention, and used currently mostly for recreation. A construction project upstream of the park dumped FAR more sediment into the reservoir (affecting the biotic community) and resulted in its needing dredged than years upon years of erosion from the mostly mediocre but occasionally crappy trails in the park that occurred in a landscape with fairly steep slopes, somewhat high annual rainfall, and clayey soil with a high rock content (which limited sediment transportation in all but the worst trail segments).


I too have seen a construction project put far more sediment into a lake/detention pond than any amount of trail building, sustainable or unsustainable, ever could.

Cattle, crops, agriculture are far bigger sources of sediment than any mt bike trail... and I'm not about to stop eating.


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## Harold (Dec 23, 2003)

Like I said, it is up to the land manager to determine what is unacceptable.

But we need to also be aware of how erosion occurs on a trail and how the trail design minimizes it. Knowing how to counter an overzealous NIMBY environazi in an intelligent manner is important.


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