2009 California Water Code - Section 4125-4126 :: Article 2. By Owners Of Reservoirs

4125.  The owner of every reservoir which is subject to regulation
by a watermaster and which is located across or upon the bed of a
natural stream or requires the use of a natural stream channel shall
construct and maintain such measuring devices below the reservoir in
the stream and such measuring devices above the reservoir on each
stream or source of supply discharging into the reservoir as may be
required and approved by the department for the purpose of assisting
the department or the watermaster in determining the amounts of water
to which the owner is entitled and the amounts of water which the
owner is diverting, storing, and applying to beneficial use.

4126.  If the owner of any reservoir neglects or refuses to
construct and maintain the measuring devices provided for in this
article after 30 days' notice by the department, the watermaster may
open the outlet of the reservoir and the outlet shall not be closed,
except by order of the department, until the requirements of the
department as to the measuring devices are complied with.