Environmental quality of Lower Little Bow River and riparian zone along an unfenced reach with off-stream watering

Abstract

► We evaluated off-stream watering on riparian zone and river. ► Off-stream watering reduced cattle on the river bank and in river. ► The BMP improved riparian health and prevented river pollution by cattle. ► Certain vegetative properties were improved at the cattle access site. ► Rainfall simulation quality at cattle access site was not affected. The goal of beneficial management practices (BMPs) such as off-stream watering without fencing is to direct cattle away from rivers, improve the environmental quality of the riparian zone, and prevent or reduce river pollution. We conducted a four year (2005–2008) study on an unfenced 1.3 km reach of the Lower Little Bow (LLB) River in southern Alberta, Canada where three off-stream watering systems were installed 290 to ≥730 m from the river in August, 2005. Our hypothesis was that off-stream watering would reduce cattle activity at the river, improve riparian health, prevent river pollution by cattle, and improve the soil, vegetative, and rainfall simulation runoff variables at a cattle access site near the river. Off-stream watering did not significantly ( p > 0.10) reduce the median number of cattle on the river bank, in the river, or drinking from the river one year later. However, there was a reduction of 20% ( p = 0.15) for median number of cattle on the river bank and a 72% reduction ( p = 0.20) for cattle in the river. The BMP moderately improved the riparian health score from 60% (2005) to 65% (2007). Our spatial analysis (upstream–downstream) of base-flow during the post-BMP period (2006–2008) suggested that off-stream watering prevented river pollution by cattle for the majority of water quality variables measured. Canopy cover at the cattle access site near the river was significantly ( p ≤ 0.10) increased by 26–53% one and two years after the BMP. Two years after the BMP was implemented, total basal area, biomass, and mulch were significantly increased by 37–106%, while bare soil and NO 3 -N in surface soil were decreased by 38–89%, respectively. In contrast, other vegetative and soil properties were not significantly improved. Concentrations of the majority of N and P fractions in rainfall simulation runoff were not significantly reduced, and may be related to the high precipitation in the pre-BMP year of 2005. We accept the hypothesis that off-stream watering improved riparian health, prevented river pollution by cattle, and improved certain vegetative (canopy cover, total basal area, mulch, bare soil) and soil properties (soil NO 3 -N) near the river. However, we reject the hypothesis that off-stream watering improved other vegetation (live basal area) and soil properties (bulk density, NH 4 -N, total N and C), or improved rainfall simulation runoff quality near the river. Although we cannot statistically prove that the positive benefits of off-stream watering on certain environmental variables was due to reduced cattle activity, the non-significant reductions in cattle activity suggested this may be a possibility.