I don't want to cause too much alarm, but there are poisonous plants in Larimer County.  In 2015, a dog ate a plant at Horsetooth Reservoir and he was dead within an hour. So, you do have to be on the lookout this summer.  The 3-year-old border collie mix ate a water hemlock, which can sometimes be mistaken for wild parsnip or wild carrots.

According to KDVR in Denver:

The dog died while being taken to the Colorado State University Veterinary Teaching Hospital. A necropsy determined the dog died from consuming a water hemlock plant. If consumed, symptoms include drooling, muscle twitching and seizures.

Here is a YouTube video that is very helpful in identifying water hemlock. The first part of the video is identifying poison ivy. The part about hemlock is 6 minutes into the video: