The P.E.I. government is changing the rules that set out how much water municipalities can take from Island waterways.
The new limits are meant to protect wildlife and aquatic habitat.
Environment Minister Janice Sherry said the province is modernizing what is considered an acceptable amount of water to draw from a watershed. Previous models were based on recharge rate, essentially the amount of rain that fell on the watershed.
The new limit will use baseflow, which is the amount of water that runs through the streams and rivers, not counting major rains. This is considered to be a more reliable measure of the volume of flow that is coming from groundwater.
"We needed to go further and look at it from a more scientific approach," said Sherry.
"That was actually recommended to us from the Canadian River Institute."
Baseflow determinations require measuring the flow in streams at various locations in different conditions over the course of a year. These measurements have already been taken for Charlottetown's soon-to-be-developed water source in Miltonvale Park.
Under the new rules, municipalities will be allowed to take up to 35 per cent of the baseflow value from a watershed.
Charlottetown, which came under fire last year from Environment Canada for drawing too much water from the Winter River watershed, has been given two years to come up with a plan spelling out how it will eventually follow the new guidelines, but no deadline to actually implement them.
Critics say that is too much time.
Don Mazer of the Winter River Watershed Association said a generation's worth of fish of all kinds was lost last year when parts of the Winter River ran dry.
"By the time you get to the situation we were in last year, where you actually see surface water drying up, then the underlying problem has reached kind of a crisis level," said Mazer.
The association says government hasn't yet shown the new policy will keep the Winter River flowing.