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# Definition

Irrigation water management (IWM) is the process of determining and
controlling the volume, frequency, and application rate of irrigation
water in a planned, efficient manner.

# Purpose

IWM is applied as part of a conservation management system to support
one or more of the following:

-   Manage soil moisture to promote desired crop response

-   Optimize use of available water supplies

-   Minimize irrigation induced soil erosion

-   Decrease non-point source pollution of surface and groundwater
    resources

-   Manage salts in the crop root zone

-   Manage air, soil, or plant micro-climate.

# Where used

This practice is applicable to all irrigated lands.

An irrigation system adapted for site conditions (soil, slope, crop
grown, climate, water quantity and quality, etc.) must be available and
capable of applying irrigation water to meet the intended purpose(s).

# Conservation Management Systems

IWM is generally one of several components of a resource management
system used to manage water supplied to a crop through an irrigation
system that is

part of an overall resource management plan for the irrigated cropland.

**Irrigation Water Management Planning**

IWM components of the conservation plan will contain the following
information:

-   field map(s) and soil survey information

-   crop rotation or sequence

-   recommended irrigation water application rates, timing, and method
    of application

-   locations of designated sensitive areas

-   guidelines for irrigation system operation and maintenance

IWM is most effective when used in conjunction with other conservation
practices such as irrigation system design, cover crop, residue
management, conservation buffers, nutrient management, pest management,
and conservation crop rotation.

IWM requires knowledge, skills, and desire to determine when irrigation
water should be applied. The main factors influencing IWM are

-   ***irrigation interval*** (time between irrigations),

-   ***irrigation** **set** **time*** (time water is applied), and

-   ***application rate*** (rate at which water is applied).

These parameters define the timing and duration of irrigation and the
amount of water applied. System design and maintenance are also
important factors influencing IWM.

# Water Rights

Under Oregon law all water is publicly owned and anyone planning to
store or divert surface or groundwater for the purpose of irrigation
must obtain a permit or water right from the Oregon Water Resources
Department. These permits or water rights must be obtained prior to the
use of the water. It is the responsibility of the landowner to file for
the necessary permits or water rights. The landowner should complete a
*Producer Self-Certification of Irrigation History* (OREGON BULLETIN NO.
OR210-2007-2).

# Operation and maintenance

The operation and maintenance (O&M) aspects applicable to this standard
consist of evaluating available field soil moisture, crop
evapotranspiration rates and changes in soil intake rates and adjusting
the volume, application rate, and/or frequency of water application to
achieve the intended purpose(s). A review of the effectiveness of the
IWM Plan is useful in evaluating the effectiveness of the Plan and its
implementation.

####### Other necessary O&M items are addressed in the physical component standards considered companions to this standard such as Irrigation System and Irrigation Water Conveyance.

#######  IWM Plan Specifications

An IWM Plan shall be developed to assist the irrigator or decision-maker
in the proper management and application of irrigation water. Factors to
be included in the IWM Plan include the following:

-   Statement of objective(s) for the IWM Plan

-   Description of the irrigation system and its components including
    water supply, water conveyance and application systems, and any
    water measurement devices.

-   Soils information including available water capacity, depth, and
    limiting conditions related to irrigation water management.

-   Crop information including crops grown, irrigation water
    requirements, and physical characteristics including rooting depth.

-   Description of irrigation scheduling and system management including
    methods for measuring and/or estimating crop water use and soil
    moisture levels.

-   IWM record keeping requirements of appropriate detail for the IWM
    objectives. The detail of IWM may be specified as ***Detailed** or*
    ***By Irrigation Cycle*** with the associated level of record
    keeping as appropriate for the level of detail.

-   IWM review requirements regarding the effectiveness of the IWM Plan
    and its implementation.

####### Worksheets

IWM Worksheets and Record Sheets for developing an IWM Plan and
associated reporting are contained in the Oregon Supplements to Part
652, *Irrigation Guide*, Chapters 2, 9, and 10.

The Job Sheet and Worksheets are available as MS Word .doc files
suitable for electronic fill-in. The files can be downloaded from the
NRCS Oregon Engineering web site:

<http://www.or.nrcs.usda.gov/technical/engineering/engineering.html>

Irrigation Water Flows, Volumes, and Relationships

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## 

**PLAN APPROVAL and acceptance:**

<table>
<colgroup>
<col style="width: 9%" />
<col style="width: 8%" />
<col style="width: 5%" />
<col style="width: 13%" />
<col style="width: 8%" />
<col style="width: 11%" />
<col style="width: 7%" />
<col style="width: 4%" />
<col style="width: 5%" />
<col style="width: 5%" />
<col style="width: 5%" />
<col style="width: 4%" />
<col style="width: 1%" />
<col style="width: 7%" />
</colgroup>
<tbody>
<tr class="odd">
<td><strong>Practice Code</strong></td>
<td colspan="2"></td>
<td></td>
<td colspan="2"></td>
<td colspan="2"></td>
<td colspan="6"><strong>JOB CLASS</strong></td>
</tr>
<tr class="even">
<td><strong>NO.</strong></td>
<td colspan="2"><strong>PRACTICE</strong></td>
<td><p><strong>LEAD</strong></p>
<p><strong>DISCIPLINE</strong></p></td>
<td colspan="2"><strong>CONTROLLING FACTOR</strong></td>
<td colspan="2"><strong>UNITS</strong></td>
<td><strong>I</strong></td>
<td><strong>II</strong></td>
<td><strong>III</strong></td>
<td colspan="2"><strong>IV</strong></td>
<td><strong>V</strong></td>
</tr>
<tr class="odd">
<td><strong>449</strong></td>
<td colspan="2"><p><strong>Irrigation Water</strong></p>
<p><strong>Management</strong></p></td>
<td><strong>CED-WME &amp; BCSD-Agron</strong></td>
<td colspan="2"><strong>Area</strong></td>
<td colspan="2"><strong>Acres</strong></td>
<td>40</td>
<td>320</td>
<td>640</td>
<td colspan="2">2000</td>
<td>All</td>
</tr>
<tr class="even">
<td colspan="2">Number of Acres:</td>
<td colspan="3"></td>
<td colspan="2">Job Class:</td>
<td colspan="5"></td>
<td colspan="2"></td>
</tr>
</tbody>
</table>

Plan Prepared by:/s/ Date:

Job title:

Plan acceptance by landowner/operator by:/s/ Date:

PRACTICE CERTIFICATION:

  -------------------------------- --------- --------- --------- ---------
  **Year**                                                       

  **Suitability of IWM Plan:\***                                 

  **Irrigation records                                           
  including\***                                                  

  **Individual irrigation                                        
  application amounts:**                                         

  **Application timing:**                                        

  **Total seasonal amount                                        
  applied:**                                                     

  **Review of IWM Plan and                                       
  Implementation:**                                              

  **Practice meets                                               
  specification\***                                              

  **Contract item number:**                                      

  **Approved by: /s/**                                           

  **Date:**                                                      
  -------------------------------- --------- --------- --------- ---------

\* Note **A** for **Acceptable** or **U** for **Unacceptable**