This occurs at a time when oaks are dormant and germinated annual grasses are inactive. As a result, nitrate is available to leaching and is progressively flushed from the watershed until plant uptake can begin in the spring. Figure 2 Understanding seasonal variability in nutrient transport is important when monitoring water quality. For example, if water quality samples are collected only in early winter, the concentration of nitrate would be overestimated in comparison to nitrate concentrations in spring and summer. The same concern is true for concentration variability during storms.
Nitrate concentrations rise and fall with stream flow response to storms.
If sampling does not successfully document this fluctuation, conclusions about the transport of nitrate would be inaccurate. Because results from monitoring programs have policy implications for drinking water standards and other beneficial uses, care should be taken to account for this variability by sampling once before, during, and after a storm, as well as throughout the season. The team will continue to research the functions of California hardwood rangeland watersheds. Where insights are gained they will be shared with interested landowners, land managers, and resource management agencies so that more informed, science-based policy decisions can be made concerning the interactions of land use and watershed function. The Regents of the University of California.