Arid Southwest BMP 57

Irrigation Land Leveling POLLUTANTS ADDRESSED: Nutrients and Organics, Salinity, Sediments

DESCRIPTION: Reshaping and leveling the surface of land to be irrigated allows for uniform and efficient application of surface irrigation water without significant erosion, loss of water quality, or damage to soil and crops from water logging. LOAD REDUCTION MECHANISM:

Nutrients/Organics Management – Leveling of irrigated lands reduces overland water flow thus reducing transport of nutrients and organics to adjacent streams. Salinity Reduction – Soil salts are not carried into adjacent waters by overland flow. Sediment Reduction – Leveling the area to be irrigated results in a reduction in runoff, erosion, and suspended sediments in nearby surface water.

LAND USE CLASSIFICATION:

Agricultural land ADDITIONAL BENEFITS: None POTENTIAL TREATMENT AREAS: Agricultural lands ALTERNATIVE MANAGEMENT MEASURES: Cover Crop Irrigation Water Management Seeding PERMITTING REQUIREMENTS: A grading permit may be required, contact county regional flood control district.

Arid Southwest BMP 58

Irrigation Land Leveling POLLUTANTS ADDRESSED: Nutrients and Organics, Salinity, Sediments

Level 400: MODERATE ENGINEERING

LOAD REDUCTION POTENTIAL:

LOW MEDIUM HIGH ESTIMATED TIME FOR LOAD REDUCTION:

IMMEDIATE MONTHS- > 2 YEARS 2 YEARS EXPECTED MAINTENANCE:

LOW MEDIUM HIGH ESTIMATED COST:

LOW MEDIUM HIGH PLANNING AND IMPLEMENTATION:

1. In the design consider the excavation and fill material required for or obtained from such structures as ditches, ditch pads, and roadways. The appropriate yardage shall be included when balancing cuts and fills and determining borrow requirements.

2. Consider related structures and measures needed to control irrigation water and/or storm water runoff.

3. Consider crops, method of irrigation, soil intake

rates, field slope, irrigation stream size and resulting deep percolation and runoff when determining or evaluating length of irrigation runs.

4. Consider related structures and measures needed to control irrigation water and/or storm water runoff.

5. Consider crops, method of irrigation, soil intake rates, field slope, irrigation stream size and resulting deep percolation and runoff when determining or evaluating length of irrigation runs.

6. Consider the depth of cuts and the resulting

available plant rooting depths to saline soils and to shallow water tables.

7. In areas with sediment-laden irrigation water,

consider increasing the required height of the water surface at the point of delivery.

8. Consider effects on irrigation efficiencies,

especially on volumes and rates of runoff, infiltration, evapotranspiration and deep percolation.

9. Consider effects on water flows and aquifers,

and the affect to other water uses and users.

10. Consider the effects on adjacent wetlands.

Riparian Planting Zone: Upland Zone and Flood flows. SOURCES OF ADDITIONAL INFORMATION: USDA, Irrigation Land Leveling: Conservation Practice Standard, Irrigation Land Leveling prepared for the Natural Resources Conservation Service. http://efotg.nrcs.usda.gov/references/public/NM/464.pdf EPA; Management Measures for Agricultural Sources: Irrigation Water, 1982. http://www.epa.gov/nps/MMGI/Chapter2/ch2-2f.html.