EPA has a draft Wadeable Streams Assessment (WPA) in the US, the
full report and fact sheet can be downloaded at:
Their assessment found that only 28 percent of streams are in good
condition (compared to reference sites) and 67 percent of streams are in
fair or poor condition (five percent of streams were not assessed).
Western streams were in better condition than eastern streams.
Riparian disturbance has placed over 50% of Western Mountain streams in the
fair to poor category other major impacts are phosphorous (SR
wastewater!!), sediment and mining and logging.
Seems like good evidence of need for setbacks and other tools to protect
our water future.