WSP10235

• File Number: 8281.910
• Description: Colorado River Studies and Investigations -- Grand Valley Salinity Study
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1976
• Author: Soil Cons Serv
• Title: Grand Valley Salinity Study - draft
• Water Supply Pro - Doc Type: Report/Study

.',~

<:':)
.) I
~
<:"2

I~ addition to irrigation, erosion from the upland watershed contributes

sediment and salt to the Colorado River. Sheet, rill, gully and stream-

C:::')

ty3 bank erosion resuJts in 2.9 million tons of sediment and 80,000 tons of

4 salt being added to the Colorado River.

5 DESCRIPTION OF THE GRAND VALLEY

6 The Grand Valley of Colorado is near the western edge of Mesa County.

7 Grand Junction, the largest city in Colorado west of the Continental

8 Divide, is located in the Valley. The Valley covers an area of about

9 126,000 acres. It is within the Canyon lands section of the Colorado

10 Plateau physiographic province. The Val.Jey was carved in the Mancos

11 Shale formation (a high salt bearing marine shale} by the Colorado

12 River and its tributaries and for the most part is surrounded by steep,

J3 rough terrain. Deep canyons flank the vaJley to the southwest; a

14 sharp escarpment known as the Book Cliffs rises above it to the north

15 and northeast; foot slopes of the Grand Mesa lie to the east; and rough,

16 broken and steep, hilly land that borders high terraces of mesas lies to

17 the south. Within the Valley, the irrigated lands have developed on

18 recent alluvial plains consisting of broad coalescing alluvial fans and

19 on older and higher alluvial fans, terraces, and mesas.

20 The mean annual temperature at Grand Junction is 52 F. and ranges

21 from a July mean of 78 F. to a January mean of 26 F. The annual preci-

22 pitation averages only 8.29 inches and is rather uniformly distributed

23 "throughout the year. The elevation at Grand Junction is around 4,850
24 feet above sea level. The average growing season is 190 days.

13

. ---