There are many sources of studies and public information available on Twitchell Dam and Reservoir documented by private organizations, as well as by federal and state agencies, over several decades. There is no argument that the reservoir is choked with silt and sediment accumulated over decades and is unable to store the reservoir's original historical water capacities... and certainly not enough water capacity required for essential agricultural purposes downstream.
One example:
Sedimentation is a problem for the reservoir, as the reservoir is being filled faster than expected. This reduces its capacity and blocks the water inlet to the control gates. Some sediment has been removed by flushing it out during releases, but much of it is simply deposited immediately downstream, interfering with flows.
Bureau of Reclamation State: California Region: California-Great Basin Region OWNER Title: Area Office Manager Organization: South-Central California Area Office Address: 1243 "N" Street City: Fresno, CA 93721-1813 Phone: 559-262-0300 OPERATOR Organization: Santa Maria Valley River Water Conservation District Address: PO Box 364 City: Santa Maria, CA 93456 Fax: 805-739-0763 Phone: 805-925-5212 https://www.usbr.gov/projects/index.php?id=193