D. On photo
The North and Middle Forks of the Flathead River bound the park on the west and southeast sides, respectively. For the most part, that development is residential with a low potential for significant water degradation. Commercial and industrial development could be another story. Talks waver back and forth about possible coal mining in the Canadian North Fork, and the effluents from those activities would flow along the entire western edge of the park. Proposals to pave the North Fork road could mean an increase in vehicle travel next to the river and much higher potential for commercial development. As usual, vigilance about the possibilities will determine the future quality of Glacier's water. Large fires tend to increase the nutrient load in streams (from erosion) in the short-term, which can be both negative and positive. Long-term, the effects are neutral or positive.
An incremental threat also exists. Because so many of Glacier's lakes are cold, sterile and subject to heavy precipitation, pollution carried in by air transport -- rain, snow and particulates -- is showing up in those lakes. Monitoring of the air / water relationships is ideally done here, as a baseline for those effects everywhere else. Once again, Glacier's size and wildness makes it the ideal place for measuring global effects.