General aviation pilot reported a traffic conflict with another aircraft initiating their takeoff while the pilot was on final approach at a non-towered airport. The pilot performed a go-around and returned for a landing.

Narrative

While landing from an ifr flight in VMC conditions to runway 34 at CLW; while short final to runway 34)estimated distance above ground to be 139 feet) Aircraft Y Announced he would be departing 34. I immediately guarded the controls and was under the impression he was simply announcing his attentions as i was already almost over the numbers landing 34. to the shock of myself and all others that witnessed; Aircraft Y decided to cut right out in front of me and depart runway 34. I immediately initiated a go around and was believed to have come about 130 feet over the top of the offending airplane. While in the climb out to rejoin the pattern; i asked multiple times why this had happened and got no response. I entered the downwind and landed runway 34 without further incident. When i walked into the FBO; i had multiple witnesses approach me and say they saw the whole thing and were scared on how close of a call it was. I submit this report in confidence and hope this pilot knows what he did and exactly how close this was to being a serious casuality. I do not believe weather to be a factor as the ceilings were 1900 above the pattern altitude.