Environmental permit handbook
The Environmental Permit Handbook is a website developed by the Washington State Office for Regulatory Innovation and Assistance (ORIA) that contains information about state and federal environmental permits, approvals, and licenses in a handbook-like format.
A dam safety construction permit is required before constructing, modifying, or repairing any dam or controlling works for storage of 10 or more acre-feet of water, liquid waste, or mine tailings.
Regardless of the proposed use to be made of the impounded waters, construction of any dam or dike that will be capable of impounding water to a depth of 10 feet or more at any point, or will impound a volume of 10 acre-feet or more at normal pool level, may not be started until a reservoir permit for such construction has been obtained from us.
This requirement is applicable to any proposed impounding structure that obstructs a stream or watercourse, and to any excavation and/or dike to be built off-channel from any stream or watercourse. This is also applicable to any impounding structure that will increase the depth or capacity of any existing reservoir such that it equals or exceeds the above standards.