R655-11-7A. Outlet Sizing

A. All dams shall have a low level outlet capable of draining the reservoir. Exemptions to this requirement may be granted at the discretion of the State Engineer. Normally, exemptions will only be considered for low head, low hazard dams. Any dead storage must be approved by the State Engineer and must be sufficiently low to eliminate any storage hazard. The outlet should be sized to meet the project demands as well as the following criteria.

1. All outlets shall be 24 inches in diameter or larger unless exempted in writing by the State Engineer. Outlets should have valves or capped flanges which can facilitate entry into the pipe by personnel or video equipment.

2. All outlets shall have the capacity to evacuate 90% of the active storage capacity of the reservoir within 30 days neglecting reservoir inflows. The State Engineer may adjust this requirement on large reservoirs if it can be demonstrated that compliance would result in an unreasonably sized outlet or potential releases would exceed the downstream channel carrying capacity.

3. All outlets shall have the capacity to satisfy prior downstream water rights and the owners' release requirements.