Home\Educate\Water Reuse 101\Research Projects\Year\2007\Salinity Management Guide: The Links Between Soil, Salt and Recycled Water

Salinity Management Guide: The Links Between Soil, Salt and Recycled Water

Project: 03-12
Type: Decision Making Tool
Year Released: 2007

Program: Principal
Funding Partners: Bureau of Reclamation, Central Basin Municipal Water District, Los Angeles Department of Water and Power, Water Replenishment District, City of Cerritos, West Basin Municipal Water District
Total Investment: $100,000 (Cash: $100,000)

Principal Investigator: Jennifer Bender, Central Basin Municipal Water District

Background

Although many opportunities exist for the use of recycled waters in urban areas and is encouraged by the State of California (California Recycled Water Task Force, 2003), there is some reluctance by landscape irrigation consumers to utilize treated municipal sewage effluents. The typical Title 22 recycled water in the area has an electrical conductivity of 1.1 dS/m, about 825 mg/L TDS, Sodium Adsorption Ratio of 3.4, and 0.6 mg/L boron. Potential recycle water customers feel that they have a choice on whether to use recycled water or potable water for irrigation. First, many landscape professionals do not fully understand that Title 22 recycled waters are safe and suitable for irrigation. Second, some landscape professionals believe that the salinity of the recycled water may be excessive and harmful to landscape plants. Given these two factors, the Central Basin Municipal Water District (CBMWD) aims to educate the public and landscape industry about the utility of recycled water to conserve potable water use, and develop a Salt Management Guide for landscape professionals.

Goals and Objectives

The project promotes the use of recycled municipal waters instead of potable waters for irrigation of landscapes through education on various salinity management techniques that may be implemented. Freshwater resources in Southern California are increasingly becoming scarce as its population continues to grow and potable waters need to be conserved and used wisely. The two principal constraints for use of recycled waters appear to be concern about potential adverse impacts of salinity levels in recycled waters on landscape plants by professional landscapers and the lack of confidence in the safe use of recycled waters by the public.

To overcome these constraints, the following project objectives have been established:

  • Literature review and summary on public health aspects and regulations on recycled waters for the safe use of recycled municipal waters, evaluation on constituents of concern in recycled waters as they may affect landscape plants, soil properties and irrigation application systems.
  • Preparation of a  “Salt Management Guide” for landscape professionals to evaluate the suitability of recycled waters for irrigation of landscape plants, methods of appraising potential salt problems and alternative management strategies to combat salt problems.
  • Preparation of a master copy educational brochure for the public about the safe use of recycled water for landscape irrigation, potential salinity problems and how they could be managed, and the value of recycled waters in helping solve current and future shortfalls in potable waters.

Research Approach

Task 1. Identification of the varying factors that control the need for salt management in irrigation with recycled water and current salt issues, followed by a detailed literature search and summary.

Task 2. Preparation of a “Salt Management Guide” that contains a guide to the suitability of recycled municipal water for landscape irrigation including effects on plants (e.g., salinity, specific ion toxicities), effects on soils (e.g., salt and sodium accumulation in soil, water intake rates), and effects on water application systems (e.g., clogging of micro-irrigation emitters).

Task 3. Preparation of a master copy educational brochure for the lay public and recycled water users informing them of the issues of salinity in recycled water. The brochure , based on information developed in the Salt Management Guide, illustrates how salinity can be managed to gain the support and confidence of the public and landscape professionals in utilizing recycled water instead of potable waters.

Findings and Conclusions

This tool helps landscape professionals accurately diagnose and manage salt-related problems. The Salinity Management Guide is an interactive, user-friendly CD that provides information varying from the basics of salinity to the design or redesign of landscape systems based on water needs, soil conditions, and the salt-tolerance of plants.

Using data and images from the Guide, landscapers will be able to compare their plants to photos of plants suffering from salt damage. With a click of the mouse, they can explore options such as selecting a more salt-tolerant plant for the landscape, checking water application rates to determine if adequate water has been used to meet the plant’s needs, or changing the water application method from one type of sprinkler to another to avoid salt damage to foliage.

It is the only database of its kind that provides information on the effects of water quality on plants, soils, and water application systems.

 

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