The study by the Sierra Nevada Alliance – looked at 24 major watersheds.
"Three-quarters had stretches that were not swimmable, fishable or drinkable at some point in time in the last five years."
Spokeswoman Megan Suarez-Brand says the results are based on publicly available data from state and federal agencies. It took 7 months to research and she says the information should be easier to access.
"So that’s one of our main recommendations is we’re trying to get the governor and the legislature to invest some more resources into having a central location where we can actually go and find out which sierra stretches had pollution problems."
She says the majority of problems were most likely caused by so-called non-point source pollution which includes excess fertilizers and insecticides, sediment from construction sites and bacteria from livestock.