WSP03721

• File Number: 8276.300
• Description: Lower Gunnison Basin Unit - Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 4
• Date: 12/1/1989
• Title: Colorado River Water Quality Improvement Program Lower Gunnison Basin Unit North Fork Area Preliminary Findings Report December 1989
• Water Supply Pro - Doc Type: Report/Study

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CHAPTER II

PIAN FORMULATIOO

Salinity control Component Descriptions and Analyses

After the subareas had been identified and the general salt loading
conditions confirmed by the EC profiles, salinity control components were
formulated for each subarea.

Tongue Creek canal and lateral lining

Area Description

The Tongue Creek drainage is located in Delta County on the south slope
of Grand Mesa. The drainage is tributary to the Gunnison River and has an
area of approximately 152,131 acres consisting of 77,608 acres of privately
owned land, 18,099 acres of public land managed by the Bureau of
Land Management, and 56,424 acres of public land managed by the Forest
Service. The 15,750 acres of irrigated land within the drainage is composed
of 3,865 acres in orchard and 11,885 acres in grain, corn, hay, or pasture.
Due to high TOS concentrations associated with irrigation return flows in this
subarea, it was considered as a candidate area for canal and lateral lining.

Snowmelt runoff is the main source of surface water, with Frui tgrowers
Reservoir and several smaller reservoirs providing approximately 20,000
acre-feet of supplemental irrigation water after the spring runoff period. No
irrigation water is pwnped from ground water in the area. Irrigation water is
supplied through 89 single owner and 178 group ditches. This drainage usually
experiences a shortage late in the season.

Approximately 486 farms are located within the drainage with an average
irrigated farm size of 33 acres. Ninety percent of the fields are less than
20 acres with an average field size of 6 acres. About 5 percent of the
irrigated land lies on fans and terraces that have alluvial profiles with some
horizontal development. A typical soil profile has dark brown to brown
surface soils grading into brown and finally pale brown in zones of maximum
lime aCcwmllation. The depth to the lime zone is usually 36 inches in the
irrigated land and 24 inches in the nonirrigated land.

Textures are loam to friable clay loam and structures are granular near
the surface becoming subangular blocky in the subsoils. The topography ranges
from 0.5 to 4-percent slope and has a smooth to slightly undulating surface
relief with permissible irrigation runs of over 500 feet. This land is well
adapted to the production of all crops grown in the area.

About 70 percent of the areas irrigated land is on soils similar to that
described above, but the topography creates short runs of less than 500 feet
on slopes between 4 to 8 percent (average slope approximately 4 percent).
Some surface rocks occur on lands near the northern margin. The remaining 25
percent of the irrigated lands have similar soil properties to that previously
discussed but is generally rocky and limited by short irrigation runs of 200
to 300 feet.

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