A perennial stream or perennial river is a stream or river (channel) that has continuous flow in parts of its stream bed all year round during years of normal rainfall. "Perennial" streams are contrasted with "intermittent" streams which normally cease flowing for weeks or months each year, and with "ephemeral" channels that flow only for hours or days following rainfall.

The Doppler effect (or Doppler shift), named after the Austrian physicist Christian Doppler, who proposed it in 1842 in Prague, is the change in frequency of a wave (or other periodic event) for an observer moving relative to its source. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from an observer. The received frequency is higher (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is lower during the recession.

Since 1944, the County of Los Angeles Department of Parks and Recreation has been meeting the diverse needs of not only residents, but also visitors from around the world. With over 63,000 acres of parks, gardens, lakes, trails, natural areas, and the world's largest public golf course system, the Department of Parks and Recreation is committed to providing the public with social, cultural, and recreational activities to enjoy the whole year.

The main function of the Civil Grand Jury is to investigate county, city, and joint - power agencies. This is a significant civil function. The Grand Jury acts in a watchdog capacity by examining carefully and completely the operations of various government agencies with in Los Angeles County. The Civil Grand Jury cannot investigate state or federal agencies, which lie outside their jurisdiction. Part of the investigation of governmental agencies includes the ability to audit operations, accounts, and records of officers and departments within the agency under investigation. The Civil Grand Jury is further charged with investigating individual complaints from citizens. By statute the Grand Jury is required to inquire regarding the conditions and management of all public prisons within the County of Los Angeles.

The Marion County Board of Supervisors has appointed a newly established Workforce Investment Board (WIB) , which will implement the Workforce Investment Act of 1998. WIB’s mandate is to provide key policy decisions affecting the local workforce development system, and to identify and certify the areas within Marion County where WorkSource Texas Centers are located to be designated as Workforce Investment Areas.