Creeks through cattle pasture never have rats for me.
That said - any water in any ditch or creek will have a rat or two - even if it is small. One tip off is if you glance at a grassy banked creek and the water is muddy - the muddy water is probably from rats. If you have rocky streams there are fewer rats. If the water is clear it doesn't always mean there are no rats but there are probably fewer. One thing those 110 traps are great for is setting in narrow spots in creeks. You want to set them in little narrow spots so the water runs through them. Rats will go through those narrow spots with running water in them. When you get a storm come through rats will move more than normal and the travel up and down stream with the high water and will go through your traps. A really great thing to look for is a pond or lake by a creek. Look for a small trail up the back of the dam between the creek and the pond. Set your 110 in that trail and you will get almost every rat in the pond and the creek eventually. These cross overs are great to catch a mink too. I use 110 traps a lot in little places. They are a great trap. Here are a couple pictures of spots they worked well for me.
Trail through grass along a creek;
Cross over on a dam;
Double on rats in a trail with running water around a spill way;
Rat in a little run with a hole at the end of it;
110 in front of a little pipe;
Brick wired to a 110 set in front of a pipe under water;
mink in the same set- see the tail in the water;
This last one is a small run along a wall where I narrowed the water with the rock you see and used the rock to prop up the 100.;
Check your laws and see if the 110 is legal to use this way. My laws might be different than yours. use your imagination and set little trails or runs you find. Sometimes rats leave very little sign. Sometimes when you catch a rat and you set your trap back you can get many rats from the same trap over and over so do the same thing over and over. I have gotten over 20 from the same set before trapping like this. As a rule you will get the local rats in 3 or 4 nights but more will come and if you set the travel routes like the creeks and cross overs you will have a steady drip drip of rats all season long plus you will get a few mink.
All of these posts give good advice. A mentor is the best. It's best to walk the streams. Its good to get your feet wet and look for tracks and sign and set on sign. Sign has o be fresh. Trapping like I do like this - the only sign I see is trails between water.
Lots of the dams I trap look like this; ste your trap in the taller grass so you can see the trail;
Many are even close to people. Check your traps early and even two times a day if you have time. This time of year rats move all day. Soon they will be moving more looking for a mate. Stop trapping when you start to see bite marks in the hide or when your rules say you have to stop. Good luck! Send us some pictures.
I trap a lot of creeks like this;
A lot of these are knee deep or less. See the rat on the left? See the muddy water? That says rats! That told me there were muskrats in this creek so I made a set with a small foothold. Make sure you have a long chain or wire if you use a foot hold trap so they make it to deep water.