Dolomedes in Colorado?
Hello--At the Denver Botanic Gardens recently, there was an enormous (3"-4") spider on a rock next to a small pond. This was the largest spider my husband and I had ever seen in Colorado. We were with our friend who is a UK entomologist; a colleague of his identified this as a female Dolomedes tenebrosus, Dark Fishing Spider. Are these often found in this state?
Denver County Colorado spiders
According to the Denver Museum of Nature and Science collection database (the best spider collection in the state), they have 11 specimens of Dolomedes, all of which being either D. scriptus or D. triton. So, most likely the individual you saw was one of these two rather than tenebrosus.