IRRIGATION WATER MANAGEMENT PLANS

Irrigation Water Management Plan For Robert Middlemist By: Joe Wang Natural Resources Conservation Service

1.

METHOD OF IRRIGATION

About 40 acres will be irrigated by an irrigation system. The area was irrigated in the past by flood irrigation from the Revais canal. The new system will consist of a gravity line from the Revais canal. There will be a pump system located in the draw to the east of the field that will be connected to the gravity system which will able to capture waste water when the flow in the Revais canal runs low in the summer. The system will consist of 6” and 4” PVC pipe.

2.

SOILS

There are two soils in the area to be irrigated. These soils are Bigarm above the road and Round Butte below the road. Design characteristics of these soils are: Infiltration Rate Inches per hour Water holding Capacity by foot Bigarm 1.4”/hour 1’/2.0” 2’/2.9” 3’/3.9” 4’/4.5” 5’/5.1” Round Butte .34”/hour 1’/2.0” 2’/4.1” 3’/6.1” 4’/8.2” 5’/10.2” 3.

CROPS

The fields will be used for pasture and hay production. Peak consumptive use of these crops for climatic area 2 are: Alfalfa .27”/day Grain .23”/day 4

WATER SUPPLY

The Revais Canal and also wastewater from the Jocko pump canal will supply the water for the system. The landowner has the water rights for this use.

Page 2 Irrigation water management plan- Robert Middlemist 5.

PEAK USE SYSTEM DESIGN

Crops to be grown Net Water to be replaced Design Efficiency Gross water application Hours per set Water use by crop Sprinkler spacing Gallons per minute per head* Above Road Alfalfa Grass 2.0” 65% 3.1” 11.5 hours .27”pre day 60 by 40’ 6.7 GPM Below Road Alfalfa Grass 3.0” 70% 4.3” 23.5 hours .26”per day 60 by 40” 4.5 GPM *Due to the variation in pressures flow control nozzles should be used.

6.

SYSTEM OPERATION

The system should be operated according to the design. Although the area is limited in the amount of water delivered to the cooperator by the Ditch Company, On a good year 12” per acre. With this in mind irrigation should be done according to the following information and also the enclosed Figure 3.1 Critical Growth Periods.

Net Irrigation Required for Alfalfa for Climatic Area 2 Spring Date May 1 June July Total Plant Use 3.70

5.70

7.51

Aug. 6.14

Fall Date Sept 29 Season Total 25.98

Eff. Rainfall 1.32

2.23

1.30

1.01

6.63

Net Irrigation Required for Grass for Climatic Area 2 Spring Date April 14 May June July Aug.

Total Plant Use 0.90

3.43

5.07

6.75

5.72

Sept. 3.12

Fall Date Oct. 18 0.97

Season Total 25.87

Effective Rainfall 0.33

1.26

2.02

1.23

0.97

0.67

0.33

6.81

Net Irrigation 2.38

3.47

6.21

5.13

2.16

19.35

Net Irrigation 0.57

2.17

3.01

5.56

4.75

2.45

0.64

19.15

Appearance of clay, clay loam, and silty clay loam soils at various soil moisture conditions.

Available Water Capacity 1.6-2.4 inches/foot Percent Available:

Currently available soil moisture as a percent of available water capacity.

In/ft. Depleted:

Inches of water needed to refill a foot of soil to field capacity.

0-25 percent available 2.4-1.2 in/ft. depleted

Dry, soil aggregations separate easily, clods are hard to crumble with applied pressure.

(Not pictured)

25-50 percent available 1.8-0.8 in/ft. depleted

Slightly moist, forms a weak ball, very few soil aggregations break away, no water stains, clods flatten with applied pressure.

OLD and NEW TOOLS

ANIONIC POLYACRYLAMIDE (PAM) EROSION CONTROL

NATURAL RESOURCES CONSERVATION SERVICE RECOMENDATIONS

MATERIAL

The polyacrylamide used for reducing surface erosion shall meet the following requirements:  be used only if officially labeled for the intended use (e.g. labeled for irrigation erosion control or wind erosion control).

 be of the anionic type meeting acrylamide monomer limits of  0.05 percent (%),   have a molecular weight of 6 to 24 Mg/mole.

be designated as “water soluble”, “linear”, or “non-crosslinked.”  be mixed and/or applied in accordance with all Occupational Safety and Health Administration (OSHA) Material Safety Data Sheet requirements and the manufacturer’s recommendations for the specified use.

 conform to all federal, state, and local laws, rules, and regulations.

POLYMER APPLICATION RATES

For furrow irrigation   Maximum application rate shall be a 10 ppm.

Application shall occur only during the advance phase of surface irrigation.

 Dry or “patch” treatments of PAM shall be placed over an area of the first five (5) feet of furrow. A starting application rate of 1 ounce per 1000 feet of furrow length is recommended. Field adjustment (increase or decrease) to this application rate is required. The rate should be adjusted until no visible erosion occurs.

GENERAL RECOMMENDATIONS

Follow a recommended irrigation water management plan.

Use polyacrylamide on each irrigation that follows a soil disturbance operation, particularly the first irrigation of the season. Reapply the polymer when excessive erosion is noted.

Based upon soils, slope, and stream size, the necessary concentration of polyacrylamide may be reduced. For the best and most economic concentration, back off on the amount of polymer used until soil movement is noted, then increase slightly.

Turbulent mixing of the polymer is critical. The following are general mixing recommendations for granular liquid and solid PAM for irrigation applications:  Application of PAM should be sufficiently upstream from the irrigation set that thorough mixing has occurred. In open ditches let water pass over at least one drop or ditch obstruction. In earthen ditch a drop dam is recommended. If drop of obstruction is not feasible place PAM 100 to 300 feet upstream of first set. This may be reduced to 25 to 50 feet if liquid PAM is used.

 Lack of adequate turbulence is generally indicated by jellying and deposition of polymer material downstream of the application point  In gated pipe the swirling action of 2 to 3 pipe sections is usually enough turbulence to adequately mix PAM. If unable to obtain these lengths use inline drop structure or install baffles in the first pipe.

 Solid formulation of PAM should be placed in areas where turbulence is occurring. The action of the water dissolves the PAM.

Control of the concentration is difficult, as location and time are the only variables for control. A trail and error of adjusting approach should be used the amount and location while visually observing furrow erosion.

For liquid or granular PAM application to open ditch place the discharge point at least 2 feet from flowing water. Small droplets (splash) can cause the PAM to clog the outlet.

If irrigation water is high in sediment, application of PAM to the head ditch or lateral may cause excessive sedimentation within the ditch/lateral and lose of flow capacity. Consideration should be given to settling out the sediment in a settling pond with increased PAM application rates or by decreasing flocculation potential by applying smaller application rates (e.g. 5 ppm) while still controlling erosion.