After 100 kilometres (about 60 mi), it forms a delta where it empties into the Strait of Georgia between the mainland and Vancouver Island. The lands south of the City of Vancouver, including the cities of Richmond and Delta sit on the flat flood plain. The islands of the delta include Iona Island, Sea Island, Lulu Island, Annacis Island, and a number of smaller islands. While the vast majority of the river's drainage basin lies within British Columbia, a small portion in the delta area lies across the international border in Washington in the United States, as does the upper reaches of the tributary Chilliwack River and Sumas River.
The river's volume at its mouth is 112 km³ (27 cu mi) each year (about 800,000 gal/s or 3550 cubic metres per second), and it dumps 20 million tons of sediment into the ocean. It is the tenth longest river in Canada.
The upper reaches of the Fraser River were first explored by Sir Alexander Mackenzie in 1793, and fully traced by Simon Fraser in 1807, who confirmed that it was not connected with the Columbia River.
In 1828 George Simpson visited the river, mainly to examine Fort Langley and determine whether it would be suitable as the company's main Pacific depot. Simpson had believed the Fraser River might be navigable throughout its length, even though Simon Fraser had described it as non-navigable. Simpson journeyed down the river and through the Fraser Canyon and afterwords wrote "I should consider the passage down, to be certain Death, in nine attempts out of Ten. I shall therefore no longer talk about it as a navigable stream". His trip down the river convinced him that Fort Langley could not replace Fort Vancouver as the company's main depot on the Pacific coast.
Much of British Columbia's history has been bound to the Fraser, partly because it was the essential route between the Interior and the Lower Coast after the loss of the lands south of the 49th Parallel with the Oregon Treaty of 1846. It was the site of its first recorded settlements of Aboriginal people (see , St'at'imc and Nlaka'pamux), the route of multitudes of prospectors during the Fraser Canyon Gold Rush and the main vehicle of the province's early commerce and industry.
This river has been designated a Canadian Heritage River for its natural and human heritage.
The Fraser is heavily exploited by human activities, especially in its lower reaches. Its banks are rich farmland, its water is used by pulp mills, and a few dams on some tributaries provide hydroelectric power. The main flow of the Fraser has never been dammed as its high level of sediment flows would result in a short dam lifespan. Today, Fraser Herald at the Canadian Heraldic Authority is named after the river. In 1858, the Fraser River and surrounding areas were occupied when the gold rush came to the Fraser Canyon and the Fraser River.
The first disastrous flood in the Fraser Valley occurred in 1894. With no protection against the rising waters of the Fraser River, Fraser Valley communities from Chilliwack downstream were inundated with water.
After the 1894 flood, a dyking system was constructed throughout the Fraser Valley. The dyking and drainage projects greatly improved the flood problems, but unfortunately over time, the dykes were allowed to fall into disrepair and became overgrown with brush and trees. With some dykes constructed of a wooden frame, they gave way in 1948 in several locations, marking the second disastrous flood.
1894, June, the Fraser River flooded Chilliwack and the Fraser Valley. The high water mark at Mission reached 25.75’.
1948 saw massive flooding in Chilliwack and other areas along the Fraser River. The high water mark at Mission rose to 24.7’.
At the height of the 1948 flood, 50,000 acres stood under water. Dykes broke at Agassiz, Chiliwack, Nicomen Island, Glen Valley and Matsqui. By the time the flood waters receded a month later, 16,000 people had been evacuated, damages totaled $20 million.
Due to record snowpacks on the mountains in the Fraser River catch basin which began melting, combined with heavy rainfall, water levels on the Fraser River rose in 2007 to a level not reached since 1972. Low-lying land in areas upriver such as Prince George suffered minor flooding. Evacuation alerts were given for the low-lying areas not protected by dikes in the Lower Mainland. However, the water levels did not breach the dikes, and major flooding was averted.