Field Application of PAM to Water Delivery Canals - R. Susfalk, D. Smith, B. Epstein, T. Gates, C. Martin

Although the application of granular PAM to a canal seems straight-forward, there are several factors that must be considered for a successful application. These factors include, but are not limited to, the type of soil, suspended sediment concentration, water temperature, water velocity, water chemistry, and the methods used to apply PAM. In general: 1) greater seepage reduction should occur in canal waters containing sufficient concentrations of divalent cations and finer-grained suspended sediments, and; 2) warmer water temperatures and lower water velocities should reduce the downstream distance that PAM can travel before it is reactive.

The objectives of these field applications are to: 1) assess how PAM is applied in order to maximize seepage reduction benefits and to minimize environmental impacts; 2) estimate the efficiency of PAM to alter seepage; and 3) monitor the downstream transport of PAM and AMD in the water column. The Research Consortium has applied or monitored the application of linear, anionic PAM to 13 canal reaches in Colorado and Montana through 2006. These canals have ranged in size from 3 cfs to over 800 cfs in size. Additional experiments are being conducted in eastern Colorado in 2007.

Aquatic systems support a wide diversity of life that is influenced by environmental conditions. A number of studies examining relationships between aquatic benthic macroinvertebrate (BMI) communities and characteristics of their environment show that differences in the structure of BMI communities is reflective of conditions in the aquatic environment. DRI will examine BMIs in specific reaches of irrigation canals as a means to: (1) compare the structure of pre and post-treatment benthic communities in treated and untreated reaches of a small irrigation canal, and (2) assess the effect of PAM on the structure of drifting macroinvertebrates during treatment in a canal. The goal will be to link the predictions of fate and transport with the effects on BMIs in canals and receiving waters. Effects of PAM on BMI communities will be determined following standard bioassessment protocols with taxa identified to the lowest possible taxonomic level.