Symptoms - Hidden Streams
The watersheds in the Lower Fraser Valley (LFV) have been subjected to intense urban and rural development pressures for many decades. The great majority of pre-settlement streams in the Vancouver area have been buried or culverted, and many are effectively lost.
Lost can be defined as lost, endangered, threatened, or wild, based on the number and types of impacts on the stream, including channelization, water diversion, removal or alteration of riparian vegetation, and pollution.
Most of the remaining streams in the Lower Fraser Valley have been altered in one or more ways, including channelization, diversion, removal or alteration of riparian vegetation, and by pollution.
The area includes all the streams from the Strait of Georgia east to the Coquihalla Watershed (Hope), and from the North Shore Mountains to the United States border.
Streams are classified as lost if they have been culverted, paved over, drained or filled, and generally no longer exist as a surface waterway. Over the past one hundred years of settlement in the Lower Fraser Valley, many streams have been lost – culverted, paved over, filled in. At times it is difficult to determine the exact cause of their disappearance since streams have also been channelized, redirected into other watersheds, or cut off from their tributaries. There are approximately 117 streams, many of them salmon bearing, appear to have been physically lost in the Lower Fraser Valley since records first started to be kept.
Lost streams include those that no longer exist, or have been severely altered with much of their length now underground. It should be noted that this lost streams total represents a conservative count; further research would be needed in order to determine a more exact figure. Also, it must be appreciated that many other streams have been converted into ditches and these latter streams are considered endangered.
Streams in the Lower Fraser Valley where the land base has been converted from forests to agriculture, industry, and housing have sustained the greatest impacts. The development footprint in the Lower Fraser Valley has left a devastating impact on most streams, many of which historically supported, and some of which still support, viable salmon populations.
A survey examined the condition of 779 of the large, medium and small streams in the Lower Fraser Valley. Of these, approximately 117 streams have been lost (no longer exist) in the period between 1860 and the present. Most of the remaining 662 streams are under significant stress due to landscape alterations in watersheds, riparian zone degradation, and pollution, and are classified as threatened or endangered. A few streams remain in a relatively wild state.