Arrowcreek Reuse Irrigation Water Quality Analysis

As a sub-consultant to One Water Consulting and under contract with Washoe County, this study was triggered by observations of stunted and poor growth of specific landscape species, in the Arrowcreek subdivision, irrigated in part with reuse water from the Truckee Meadows Water Authority. This pioneering project specifically looked at pH and boron in replicated samples, unusual for landscape projects versus agriculture where there is an economic incentive. During the summer and fall of 2018 as part of Phase Two, and with County interns conducting the sampling, we sampled a number of parameters for reuse and potable water landscaped areas. These parameters included water quality, plant tissue, and soils in affected (reuse) and reference areas. Preliminary analysis indicates the boron, although not present in high concentrations in reuse water, accumulates in the soil and can have adverse impacts on certain plants. Final analysis was completed in the spring of 2019.

It appeared that the most sensitive species to growing conditions, which are multivariate and include irrigation and soils, were Colorado Blue Spruce and Scotch broom. It must be noted that although a number of species do concentrate boron in leaf and needle tissue, this does not necessarily correlate with plant health. Therefore, plant tissue analysis for this project may not have been the best manifestation of interactions between soil and irrigation water.

It appears that a combination of water quality and irrigation practices have resulted in stress among some species as both boron, and sodium to a lesser extent, showed accumulation in soil samples.