California Native Plant Society
San Gabriel Mountains Chapter

Lily Spring Area Survey — maps

Maps of Lily Spring survey area

Here are links for downloading maps of the Lily Spring area. These are cropped from the USGS 1:24000 topographic map, Crystal Lake. Various places on the internet dscribe how to read a USGS topographic map, including an explanation of the Public Lands Survey System, i.e. how to record specific locations. A good reference is Paradise Valley Community College.

Map with Sawyer's survey area marked, as per his Crossosoma paper. Resolution 2091 x 1414 pixels. This map includes the Section boundaries and divisions, which may be of use for recording plant locations when no GPS receiver is available.
- JPG file (0.8 MB), a compressed file with some loss of definition, but will download faster
- JPG file (5.3 MB), with minimum compression
- TIF file (7.6 MB), with zero loss from data compression

Map with Sawyer's survey area marked, as per his Crossosoma paper. Resolution 2091 x 1414 pixels.
- JPG file (0.8 MB), a compressed file with some loss of definition, but will download faster
- JPG file (5.3 MB), with minimum compression
- TIF file (7.6 MB), with zero loss from data compression

Map with no markings (does not show Sawyer's study area): Resolution 2091 x 1414 pixels.
- JPG file (1.3 MB), a compressed file with some loss of definition, but will download faster
- JPG file (4.7 MB), with minimum compression
- TIF file (7.7 MB), with zero loss from data compression

The seven crests and other locations

The LSAS field reports make occasional mention of location with respect to seven crests along the ridge that forms the southern boundary of the study area. During the survey we often referred to these as Crest 1 through Crest 7, numbered from west to east.

Click here for a map showing the seven crests (1200 x 800 pixels, 236 KB), as located by a personal GPS receiver, accuracy 10 feet.

Here are the elevations and geographic coordinates of the seven crests. Crest 6 is close to the intersection of the Pacific Crest Trail (PCT) and the trail sothward to South Mt. Hawkins. Crest 7 is at the top of Claude's Ridge, which extends downward in a northwesterly direction to the highway. Note that the crests are all slightly south of the PCT because in the study area the PCT does not go along the actual crest except in a few places such as at Windy Gap.

Crest Elevation Latitude Longitude
Crest 1 7,698 ft N34 20.575 W117 49.666
Crest 2 7,972 ft N34 20.456 W117 49.464
Crest 3 8,240 ft N34 20.456 W117 49.282
Crest 4 8,430 ft N34 20.415 W117 49.125
Crest 5 8,402 ft N34 20.421 W117 48.930
Crest 6 8,437 ft N34 20.391 W117 48.831
Crest 7 8,587 ft N34 20.496 W117 48.636

Here are the elevations and geographic coordinates of some other locations frequently discussed and noted by survey participants. Regarding the Mile Markers (MMs) on Angeles Crest Highway (State Route 2), note that MM 62.28 is approximately the western boundary of the study area, whereas MM 67.86 is close to the eastern bounday of the study area. The location of MM 67.86 may be uncertain as it appears to have been moved during the study period, the actual boundary of the study area being on the eastern side of the drainage gully where that MM is located (South Fork of Big Rock Creek).

Location Elevation Latitude Longitude
Little Jimmy Spring 7,428 ft N34 20.737 W117 49.762
Windy Gap 7,588 ft N34 20.603 W117 49.754
Lily Spring Campground 8,013 ft N34 20.694 W117 48.601
Mile Marker 62.28 7,258 ft N34 20.773 W117 49.679
Mile Marker 66.37 7,276 ft N34 20.719 W117 49.630
Mile Marker 66.43 7,260 ft N34 20.724 W117 49.580
Mile Marker 66.82 7,300 ft N34 20.719 W117 49.209
Mile Marker 67.70 7,520 ft N34 20.874 W117 48.616
Mile Marker 67.86 7,530 ft N34 21.006 W117 48.608

Accuracy of USGS 7.5-minute quadrangle topographic maps

Here is an extract from the USGS Map Accuracy Standards web page:

The horizontal accuracy standard requires that the positions of 90 percent of all points tested must be accurate within 1/50th of an inch (0.05 centimeters) on the map. At 1:24,000 scale, 1/50th of an inch is 40feet (12.2 meters). The vertical accuracy standard requires that the elevation of 90 percent of all points tested must be correct within half of the contour interval. On a map with a contour interval of 10 feet, the map must correctly show 90 percent of all points tested within 5 feet (1.5 meters) of the actual elevation.

Note that roads shown on the map are as per the aerial photogrammetry of 1957/58, when the Crystal Lake map was made. In some places the road locations have changed. There are also trails shown that no longer exist, and more recent trails that are not shown. Although these maps were updated in 1972, it's possible that little or no updating was done on this particular map because of the remote location.

How to download the USGS topo map from the internet

To download the USGS Crystal Lake topo map from the USGS web site, follow these steps:
- Go to http://usgs.gov
- Then “Maps, Imagery, and Publications”
- Then “Download free topo maps”
- Then in the “Map Locator & Downloader” search for “Crystal Lake, CA”, using Search type “USGS Map name”
- Click on the Marker in the middle of the map, which displays available maps
- Click the “+” sign after the requied item(s) in the list.
- The selected item(s) appear in the Download Cart. (The search brings up several versions of Crystal Lake. The one that we found most useful has the number 5511899 in the ID column of the Download Cart.)
- Click the Download link(s) associated with the Download Cart.

Note: The above procedure was verified in January 2015. The procedure changes slightly from time to time as USGS update their web site.

At the time of creating this web page, the download from USGS was a PDF file with a size of 13.7 MB. (It may now be a different size.) In order to crop the map to show just the LSAS study area, Adobe Acrobat was first used to save the file in TIF format. (This generated a very large file, 182 MB. It could also be saved as a JPG file, which was only 25 MB, but that format loses some of the image quality.) Then PaintShop Pro was used to crop the image and create the files listed above for download. (One could also use Adobe Photoshop for this.) The USGS web site also has a mechanism for cropping files.

An alternative download source for the USGS topo map is the Cal-Atlas web site. This source provides maps in TIF format, which may be more convenient for some people. There is a slightly lower image quality than for the PDF files downloaded from USGS. To download the Crystal Lake topo map from Cal-Atlas, follow these steps (verified in January 2015):
- Go to http://atlas.ca.gov/download.html
-
In the long list in the middle of the page, click on Imagery, Base Maps, Land Cover
- Clicks on Base Maps
- Click drg
- Click 75_minute_Series_albers_nad83_untrimmed (or _trimmed to exclude the bordering information)
- Click 34117
- Look down the list to find o34117c7.tif, and click to open or download it
- You can also download the file 034117c7.aux, which contains auxiliary information

Top of page

 

 

On the crest at the top of the study area

 

Lily Spring overview page