Resources for keeping slackline legal

After the whole fully-public ordeal with the legalization of slackline in Seattle, many people have written to me privately asking for suggestions or sharing of whatever resources I may have in order to assist them in pursuing a similar course of action in their own communities. Unfortunately some of you are up against a tougher situation than I was (e.g. a law against attaching anything to trees). Every state, county, and even municipality will differ in laws and official viewpoints, but some generalizations can be made.

I think this basic advice should apply to 99% of the municipalities in the United States: pad your line where it attaches to the tree, and pad it well. Be respectful of the community, and be careful that your line is not rigged such that it could hurt someone (e.g. a bicyclist, jogger, etc). If you do that, it’s a good assumption that your setup is 100% legal and you will never, ever have a negative encounter with anyone, let alone a park employee.

For those who have had a negative encounter and need some help, this page is very much a work in progress right now (August 10, 2011), but I’d like to get the framework up and then see how much I can fill in. As I see it, concerns over slacklining break down into a few main categories:

DANGER. This is a big issue for some. (1) Maybe you fall and get hurt. (2) Maybe someone sees you on the line, decides to get on it when you’re not looking (or setup their own) and they get hurt. (3) Maybe someone doesn’t see the line at all and guillotines his waist.

Issue one could certainly happen. In many states you would not be able to sue, however. For instance, in WA state, RCW 4.24.210 states that as long as the Parks Dept (or any other lawful landowner) does not charge a fee then it shall be held immune in cases of lawsuit for ourdoor recreation (including but not limited to hanggliding, paragliding, hunting, and so on). In CA, CGC Section 831.7 says that public entities and employees are not liable for hazardous recreation outcomes. It is my belief that many if not most other states have similar laws.

Issue two could happen too, but again, the laws cited above would apply. Other helpful logic to employ would be to point out similar activities that exist already that pose more harm. For instance, throwing a baseball could certainly harm someone (let alone a bat-propelled baseball) but I have never seen people ejected from a park for playing ball. Many parks also have ‘intense’ playground equipment … some Seattle parks have very long (and fun!) zip lines, for instance, so if you can point out a local park that has obviously risky equipment (how many fingers and patches of hair have found their way into zip lines over the years?!), that may help.

Issue three could also happen. Keep in mind though that most slacklines are typically mounted very low so there is minimal risk of injury or “clothesline” type strikes. Listed below are the primary playground hazards according to the Handbook for Public Playground Safety published by the U.S. Consumer Product Safety Commission (CPSC). The hazards are grouped by their applicability to slacklining, with appropriate recommendations and considerations where necessary:

Not applicable to slackline: Possibly applicable to slackline: Recommendations for avoiding these hazards:
• Crush and shearing points
• Entanglement and impalement
• Entrapment (e.g. of head)
• Sharp points, corners, and edges
• Suspended hazards: Children using a playground may be injured if they run into suspended components (such as cables, wires, ropes, or other flexible parts) hanging from one piece of the playground equipment to another or to the ground. Cables, wires, ropes, or similar flexible parts suspended between play units or from the ground to a play unit that are within 45 degrees of horizontal are considered suspended hazards. • The slackline should not be located in high traffic areas.
• The slackline should be brightly colored for added visibility.

Most applicable to slackline:
• Tripping hazards: Play areas should be free of tripping hazards (i.e., sudden change in elevations) to children who are using a playground. The two most common trip hazards are anchoring devices for playground equipment and containment walls for loose‐fill surfacing materials.

As you can see, slacklines are compliant with consumer safety standards for playground equipment; it would stand to reason that if slacklines can be safe for five- and six-year-old children, that they would be safe for general park users. A minimal amount of research will show that they are endorsed by municipalities all over the United States. Santa Monica is one municipality I can personally speak for, and although they had some concerns at first, a reasonable policy was easy to draw up. Seattle Parks and Recreation has also recently followed suit.

TREE OR PROPERTY DAMAGE. This is also a very real concern. Trees have a circulatory system just undernearh their bark, and damage to the bark and underlying biologic structure could permanently harm or even kill the tree. In theory. I have yet to see this happen. Slackliners have been operating for decades without tree padding and I have yet to hear of a credible instance of a tree dying.

I always use tree padding, if for no other reason than to protect my equipment and to send a good message about our sport. I recommend you also use tree padding. I prefer towel strips, but carpet and foam work well too.

My first point here would be to iterate that Yosemite park for many years has had an access policy for slacklining. If tree padding is in compliance with National Park Service guidelines for acceptable use then why should it not be good enough for your local city park?

My second point would be to show actual real-world studies of the forces required to damage trees. I will fill this section in soon.

My third point would be to show my own real-world tests of rigging on trees without padding for extended periods. I am considering seeking permission from a forest owner to a rig a couple of permanent lines on some different species of trees to prove once and for all whether prolonged tension/abrasion will kill a tree. For now, please accept this image as proof that some trees can withstand significant scarring. While I would never reccommend causing that sort of damage to a tree, it’s proof that at least palm trees can live through almost any level of abrasion. The coast of West Africa is peppered with such still-living trees (in every fishing community I’ve seen), where boats are tied to trees and circumferential rub-marks are made as the tide comes in and goes out. Remember though, even if this doesn’t kill the tree, it obviously can cause visible damage, which is not a good thing from an aesthetic standpoint, so I think padding is still a must.

My fourth point would be to post a formal opinion paper that has been authored by trained arborists, ecologists, or foresters. I am in the process of inquiring with such experts from my local university.

EXISTING LAWS PROHIBITING SUCH ACTIVITIES. This is the section I can least help you with. My basic strategy is to figure out what your state laws are called (in Washington they are RCW … revised code of Washington). Then what your county laws are called (e.g. King County Code). Then your city laws (e.g. Seattle Municipal Code). Then find where they are posted online and search for permutations of “attach” and “rope” and “tree” and “damage” and so on. Most databased will allow boolean searches. That means you can search a phrase like: attach AND tree … and it will return only results with this two words. For me it took about 2 hours of searching and reading to be certain that no local laws applied to me. A reader of the site pointed out that Municode might be a good place to start looking if you can’t find your local legal database.

Although I can’t help much here with specifics, I can give you some basic advice. If you’re told your slackline is illegal, don’t be rude, but also don’t give up. Ask, politely, what law it violates. Offer your name and express right away how your main goal is to be respectful of the environment and of the law and you weren’t aware you were breaking and laws/rules. Explain that in order to let your other friends know it would be very helpful if you could figure out, ever so briefly, what the specific law is that you are violating. If you’re told you’re ‘damaging the trees’ you’ll need to use logic and wit to explain the issues mentioned in the last section (i.e. this is compliant with Yosemite guidelines, trained arborists say it’s safe, etc). If you’re told there’s a specific law against attaching ropes/wires/etc to trees, get the EXACT specifics of this law.

If such a law does exist, it’s time to lobby to change the law. You’ll need to round up lots of other local folks who have a stake in this (other slackliners) and try to get the local media involved. I will post my thoughts on this later, as it’s a Doozy. Perhaps I’ll wait until someone in this situation writes to me and expresses they need help. If that’s you, let me know!


  1. Donna says:

    Dear Adam,

    Thank you very much for posting the article about slacklining. My son was arrested last week for slacklining in Heber City park in Heber City, Utah. The sole reason Heber City does not permit slacklining in its park is because their arborist says “it will kill the trees.” If you have any additional information on specific data from arborists about the effect slacklining on trees has, I would really appreciate it!

    Thank you in advance for your help.


    Adam’s Comments:

    Man, that really sucks to hear! I will be in touch privately to see if I can help. I have been casually working on getting an opinion letter signed off for about a year now, but because we have no real issues locally and I have many other pressing things it has mostly been a “to do someday” sort of project.

  2. Christie says:


    I am wondering if you have managed to get that opinion paper signed yet? I am currently working on getting slacklining approved on the Capitol Grounds in Washington, DC.

    I had set up the line a couple of times with no problems. The first time a Capitol Grounds crew member came by, saw the padding and told me to have fun. The second time a policeman on a motorcycle came by but was more concerned about my bag being left unattended than by the line. Then yesterday when I set it up at lunch a Capitol Police Captain (not on patrol, just passing through between meetings) took the time to come over to order me to take down the line.

    We are currently discussing the laws at work here and they all revolve around injury to the trees. I keep my line properly padded at all times and have referred him to the stance of NPS at Yosemite but Capitol Grounds is its own jurisdiction. I am hoping to meet with one of their arborists and it would be very helpful if you have any contacts or opinions that you could share with me from your encounter.

    Thanks so much!

    EDIT: I will e-mail you privately. Thanks for reaching out.

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