On the Stability of the EACT Land

by Stephan Martineau & Miriam Mason Martineau

A further concern, which has arisen for many residents in the EACT watershed, in light of the planned road building and logging, is the effect, which these activities could have on the stability of the slope. It is a known fact that logging activities can have significant effects on landsliding and other terrain stability hazards. Several types of terrain instability have been noted in the Slocan Valley between Lemon Creek and Winlaw: landslides, debris flows and sinkholes (Overview Assessment of the October 1996 Landslide and Terrain Stability in the Slocan Valley BC, Vandine Geological Engineering Limited, Dec 10/96 File 96128). There still exists very little information on the subsurface geology of the area. Since March of 1997 there have been 28 landslides in the Slocan Valley, with over 60% affecting private land. The causes have often been found to be logging or road related.

The creek banks in the EACT Watershed are often steep, but they remain stable because of the forest protection. The tree roots act as a support system for the banks, while the forest canopy prevents direct impact of rain on the ground surface, reduces the amount of rain and snow that actually reach the ground by about 30% and regulates the rate at which the snow melts. For example, he soil below the planned logging road and in the planned clearcut above Lot # 8947 (according to most recent five year plans of SFP) is sandy/loam; a soil composition which is extremely susceptible to erosion. The slope gradient between the planned road and where Sawan Creek arises is 50% and tends to reduce further down.' These gradients are too steep to log and to build roads at. In general, the area where Block #1 is planned (according to the latest five-year plans and flagging), lies between 30% and 50%. If trees are cut close to the banks, further collapse of the creek banks could occur when the tree roots have rotted away and the banks lose support. The multiple draws of the EACT watershed creeks are usually less than 80 feet apart, making it impossible to cut trees and simultaneously preserve the integrity of the streams.

Until more thorough studies have been done on the stability of the EACT watershed area and Slocan Valley as a whole, and the results taken into serious consideration, further road building and logging should not proceed.