Thursday, April 12, 2012

Aerials of the Lily Point Landslide

One last bit on Lily Point for now.

1961 aerial of Landslide at Lily Point

The earliest aerial I could readily get my hands on of the Lily Point slide is the above 1961 image. In that image there is clearly a large slide area with few trees on the slide scarp. By 1975 below, the slide appears about the same except for trees becoming established on part of the slide area.

1975 aerial of Lily Point landslide

1985 Lily Point landslide

By 1985 all but the western limb and the steep headwall scarp is tree covered. Also note that the upland above the landslide has had some clearing for roads in preparation for development. This development was one of several large development schemes for Point Roberts that began in the 1980s. Two things slowed this development scheme down: one lack of potable water and two concerns about the landslide. 

1995 aerial of slide at Lily Point

By 1995 the slide area had become even more tree covered with the exception of the lower eroding slope and the very steep headwall that was too steep for vegetation. The upland area was fully tree covered again as not much had been taking place for development. It was sometime during this period that Dames and Moore, a geotech company, did an investigation of the slide area that included drilling.

The Google Earth image of the slide from 1998 shows most of the slide is now tree covered nearly 40 years after the bare expanse of the slide area visible in the 1961 image.
However, I marked the outline of the existing slide area in this image in red.

2011 Google earth image of Lily Point slide

Point Roberts residences reported hearing a loud noise from Lily Point area and seeing dust rise up above the forest in 1999. The slide is still wooded, but comparison with the 1998 image shows that the slide area has greatly expanded.


Wendy Harris said...

I am enjoying your posts about Point Roberts, particularly because I befriended some lovely residents opposing new development that they believe creates a landslide risk for surrounding properties. Too bad we can not force the Whatcom County Hearing Examiner to read your reports.

Dan McShane said...

Thanks Wendy. I am sure the Hearing Examiner has read reports I have submitted as a witness in the past.