Water Resources Professional Project Reports

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Noticeable forest thinning began in the Santa Fe Municipal Watershed in 2003 that could change the water quality of the Santa Fe River, a major drinking water source for the City of Santa Fe. Water quality monitoring was conducted spanning five years in treated and control portions of the watershed. This report evaluates the relationship between forest thinning and selected water quality parameters including total dissolved solids, electrical conductivity, total suspended solids, turbidity, calcium, magnesium, total Kjeldahl nitrogen, total organic carbon, total phosphorous, precipitation, water yield, and discharge. It tested the hypothesis that after treatment, the watershed would become more surface flow controlled, but that concentration of different dissolved ions would be less. Three statistical tests were used to analyze the relationship between thinning and the surface water quality parameters. At unregulated flow sample locations total dissolved solids, magnesium, and total phosphorous have statistically lower medians and after thinning began; a correlation between water yield and precipitation was not found; discharge and turbidity had a less defined relationship after thinning began, demonstrating a less surface flow related regime after thinning; and TP load had a differential significance between control of a greater median than the median for treatment, that was not influenced by water yield. However, because collection of the data that provided these results only occurred for one year and many of the values were below method detection limits, this statement would be better supported by taking samples at all seasons throughout the year to determine if the flow is being more stabilized in the watershed by forest thinning activities, with a longer period of sampling, and lowering method detection limits.

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Forest thinning, Santa Fe River, surface water quality


A Professional Project Report submitted in partial fulfillment of the requirements for the Degree of Master of Water Resources, University of New Mexico