Having visited a fairly pristine site in the upper Pajaro Watershed, our next creek visit took us farther downstream to a spot where Corralitos Creek passes near the city of Watsonville, California and merges with Salsipuedes Creek. Located near a busy road and several businesses, this waterway showed signs of degradation, with litter strewn along its banks and caught in the branches of overhanging vegetation. But appearances can deceive, so students practiced water quality tests to gain a fuller picture of the stream's health.
Having studied the relationship between temperature and dissolved oxygen (DO) in preparation for the field trip, students practiced measuring DO levels to determine if this stream could support a healthy diversity of aquatic life. They also tested the levels of nitrates and phosphates to evaluate the impacts of agricultural and domestic activities occurring in the area. We found oxygen levels sufficient to support common aquatic invertebrates and fish. The presence of low levels of phosphates told us that local runoff might be a potential problem for this stream. We did not detect nitrates, but we did discuss the possible role of seasonality. In winter, farmers are generally applying fewer nutrients to their fields; our test results might turn out different if we took samples at other times of the year.
Having visited a fairly pristine site in the upper Pajaro Watershed, our next creek visit took us farther downstream to a spot where Corralitos Creek passes near the city of Watsonville, California and merges with Salsipuedes Creek. Located near a busy road and several businesses, this waterway showed signs of degradation, with litter strewn along its banks and caught in the branches of overhanging vegetation. But appearances can deceive, so students practiced water quality tests to gain a fuller picture of the stream's health.
Having studied the relationship between temperature and dissolved oxygen (DO) in preparation for the field trip, students practiced measuring DO levels to determine if this stream could support a healthy diversity of aquatic life. They also tested the levels of nitrates and phosphates to evaluate the impacts of agricultural and domestic activities occurring in the area. We found oxygen levels sufficient to support common aquatic invertebrates and fish. The presence of low levels of phosphates told us that local runoff might be a potential problem for this stream. We did not detect nitrates, but we did discuss the possible role of seasonality. In winter, farmers are generally applying fewer nutrients to their fields; our test results might turn out different if we took samples at other times of the year.
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