In San Dimas Experimental Forest, trends south to enter Big Dalton Canyon at Big Dalton Reservoir. (US-T121)
Named for Louis Pfahl, a German imigrant who lived in the area where the canyon enters Dalton Canyon. Alfred Jones, County Surveyor, to United States Geological Survey on 11/23/36 wrote: "the local officers of the Forest Service have reported that the name of Lewis Paul Canyon has become so fixed in local and map usage during the past 30 years or more that any attempt to change the spelling of the name would be difficult if not impossible with the general public...it recommends against any attempt to change the name in spite of the fact that some very old maps show the latter as 'Louis Fall Canyon', which itself may have been a mis-spelling for Louis Pfahl Canyon'. (US-T121)