Calibration of paired basins prior to streambank fencing of pasture
Journal of Environmental Quality , 28 , 1999
Streambankfe ncing is a best managemenptr actice that is targeted to reduce suspended sediment and nutrient inputs to streams by reducing direct inputs from animals, eliminating streamhanktr ampling, and promoting streambank revegetalion. A paired basln study is being conducted in two small adjacent basins to determine the waler quality effects of streamhankfe ncing. This article documenttsh e 3-yr callbralion period between control and treatment basins prior to fence installatlon. Approximately 70% of land adjacent to streambanks in the study area is used as pasture. Nutrient quantities applied as manure, benthic-macroinvertebrate communities, and the physical habitat of each stream were similar in both basins. Total N, P, and suspended sediment yields measured al lbe outlet of each basin averaged about 56, 2.8, anti 2650 kg ha-1 on an annual basis. For both basins, about 90% of the total N yield was attributable to dissolved NO.~-N and about 90% of the total N yield occurred during nonstormflow; conversely, about 90% of the tolal P yield was altributable to stormflow and 60 to 65% oflhe total P yield was suspended. Regression equations developed between both basins for low flow and stormflow samples for nutrients, suspended sediment, and discharge indicated a significant relation for most constituenls. Pretreatment relalion between basins for low flow and stormflow samples would need to change by 6 and 14% for total N concentrations and 24 and 9% for total P concentrations in order for streambank fencing to significantly affecl water quality in the treatment basin.