Beautiful Taggart Lake lies below the massive Grand Teton, in Grand Teton National Park. Given its limited watershed, it was surprisingly green. This could be due to the recent spring runoff bringing in the annual supply of nutrients.
According to Wikipedia, "there is a significant inflow of phosphate from natural phosphoria sources (Trophic State Evaluation for Selected Lakes in Grand Teton National Park", AWRA Paper Number 98141, J. Shaun Dustin and A. Woodruff Miller). Turbidity is low and pH levels in Taggart Lake have been measured in the alkaline range of about 8.5 to 8.7."