PAM: Evaluation of Polyacrylamides to Reduce Seepage from Unlined Water Delivery Canals

pam.dri.eduPolyacrylamides (PAMs) are a broad family of polymers having varying physical and chemical properties that have been historically used in food packaging, paper manufacturing, waste water treatment. Extensive research has been conducted on the ability of PAM to reduce erosion associated associated with furrow irrigation. More recently, linear anionic PAM has been used in irrigation and water delivery canals for water conservation purposes.

By some estimates, as much as 50 percent of the water flowing through irrigation canals is lost due to seepage through the bottoms of the unlined canals. In the western United States, it has been estimated that there are 12,000 miles of unlined canals that could be susceptible to seepage losses. Hard numbers of water loss are very difficult to obtain at specific sites because field measurements are not typically available or are not precise enough to measure flow changes. Nonetheless, any cost-effective technology that can be used to conserve water in canals could bring significant benefits to drought-stricken areas of the United States.

pam.dri.eduThe ability of PAM to reduce seepage has spread through word-of-mouth and the efforts of local water managers and agencies. PAM is already being applied to some canals. Treatment was found – in some cases – to be effective at reducing seepage; however, often the observations are anecdotal and not peer reviewed or published. Thus, it is not possible to take the specific PAM application methods and relevant field conditions, and predict whether the application would be effective, or whether the use of PAM could lead to health or environmental impacts.

With funding provided by U.S. Department of the Interior's Water 2025 Program, a research consortium comprised of the DRI, U.S. Bureau of Reclamation (USBR), University of Nevada, Reno (UNR), and Colorado State University (CSU) have been investigating the risks and benefits of using linear, anionic PAM as a water conservation tool in water delivery canals.

Tasks include:

  1. to develop a toxicological risk characterization document based on a synthesis of existing PAM-related publications;
  2. establishment of a peer review panel to guide the risk characterization and research;
  3. laboratory-scale research that primarily addresses sealing mechanisms and the impacts on invertebrates and macroinvertebrates;
  4. rapid meso-scale experiments on PAM application techniques;
  5. field-scale research to assess PAM application methodology, environmental concentrations, and seepage reduction efficiency; and,
  6. the development of predictive tools to assess the downstream fate and transport of PAM.