Fishermen fish so they can enjoy their day. Trespassing is often unintentional. Access to flowing waters is a wonderful privilege for Montana fishermen. Our states Stream Access Law opens streams and rivers to the public. This is also the most common ticketed offense by wardens.
As great as our access law is, it could be a fragile regulation. Wealthy landowners often hate for anyone to be fishing along their property. Most states allow landowners to post and make their waters private. Each time the law has been tested; a wealthy landowner has been involved. Huey Lewis has land along a bordering trout stream and hates for anyone to be in his view. The slough near his land allows for public access per the Stream Access law. 
Here are some things to know about the Fishing Access Law.
Look for public owned access points to begin your fishing day.
This law does not apply to hunting
The law does not address lakes and ponds.
A No Trespassing sign at a bridge access refers to the land, not the access.
Many landowners will allow access if asked. Make sure to have the permission in writing.
Manmade obstructions can be portaged around. This may mean above the high-water mark. Be as minimally intrusive as you can.
Natural barriers such as logs, are not covered by the law and are up for interpretation.
Landowner conflicts are most common in seldom waded areas.
It is better to avoid fishing an area if you are uncertain where the high-water marks are.
The High-Water Mark refers to a “normal flow mark”, not an annual mark. This does mean a “Flood Mark”. The mark is normally lined with debris. This does not mean 10 feet or 2 feet from. The debris line is the High-Water Mark. If you are not sure, stay in the water.
If the access and watershed land is not properly posted, it can be accessed. This means signage, painted posts with orange paint. Wooden posts are often painted at the tops. Metal posts need to be completely painted. 50 Square inches of orange is the rule. Signage needs to be visible at normal access points. You may also notice trail cams and people filming your presence. These are clues to be careful or avoid the area.
If you are approached by an angry and questioning landowner, keep your cool and stay polite. Remain respectful. These landowners will often be carrying a firearm. Explain your perspective and explain the law. De-escalate and never argue too long. Any confrontation will ruin your day. It is best to move away and off the land in question with an apology. No fish is worth a trespass issue.
Fish ethically and honestly!
Montana Grant
