The state Environmental Management Commission has approved a set of regulations designed to cut nitrogen and phosphorus pollution in Falls Lake.
The "nutrient management strategy" will take effect Jan. 15, though it could be amended by the legislature.
Falls Lake is Wake County's largest source of drinking water, but its water quality does not meet state and federal standards for drinking water reservoirs. A 2005 law required the EMC to devise a program to restore and maintain the lake at acceptable quality.
The EMC's regulations affect new and existing development, agriculture as well as sewer and septic treatment and discharge throughout the Falls Lake watershed. They prescribe a two-stage program to put the lower lake, near Raleigh's water intake, in compliance with federal water quality standards within 10 years and the entire lake in compliance within 30 years.
Environmentalists have said that is too long to wait.
"The plan is certainly not as aggressive as it should be," Karen Rindge of WakeUp Wake County said after the EMC meeting. "These rules do not ensure that Falls Lake will be clean in the long run."
But local governments that would be covered by the rules have said it will take time and continuous monitoring to determine whether the rules work as designed. They also have said it will take time to cover the costs of compliance.
May cost $1.5 billion
The state Division of Water Quality has estimated that the rules could cost taxpayers in the Falls watershed as much as $1.5 billion. Only Wake County residents get drinking water from Falls Lake, but most of the dozen or so cities and counties affected by the rules are outside Wake.
Last winter, the affected governments issued "consensus principles" they wanted the state to factor into the final rules. They included reassessing the program before stage 2 rules take effect and regular monitoring of Falls Lake's water by the affected governments, with the expectation that more and better data will show that cleanup doesn't require measures as costly as what's planned now.
The rules approved Thursday note that improving technology and test results could make revisions necessary and require assessments to begin in 2016.
