General

        We found significant changes for several of our measurements, as documented by the graphs on this page.  In general, these differences can be explained by two simple categories: changes caused by changing stream type, and those caused by changing conditions over time.  We also discuss a variable whose changes occur on a much shorter time scale than the one of this study.  We also present graphs that suggest no significant changes.
 

Changes along differing stream types

        As shown in the following graph, pH increases as water flows down the stream and away from the forested wetland of sites #1 and 2.  pH is relatively low (i.e., the waters are acidic) in the wetland due to the buildup of partially decomposed organic matter along the stream.  The humic acids released from this material decreases pH.  The remaining sites, on the other hand (#3, 4, 5, 6,  7, and 8) are set in streams flowing over exposed bedrock, rock fragments, and soil.  Once water leaves the wetland and travels through these lower streams, ions weathered from exposed rock and soil enter the water and increase the pH (making the water more basic).  We would expect the streams to continue to incerease in pH beyond our study site.  Further study would reveal the upper limit of pH along the length of the streams.

Changes over time

        The following graphs show significant changes in [Cl-] and conductivity over time.  This appears to be explained primarily by the changing amounts of precipiation.  Although we lacked sufficient data to perform the appropriate statistical analyses, the data strongly suggests an inverse relationship between the amount of precipitation and these variables.   This is intuitively clear, since we would expect that precipitation would dilute the stream water.  We can see these changes both in the presence of a single ion, chloride, and in the total amount of the dissolved ions in the water, the conductivity.

 
Changes occurring at a shorter time scale than our study

        Turbidity appears to be highly dependent on the immediate conditions at the time of measurement.  The data recorded on 2/27, presented in the following table, shows this condition.  We noted active logging occurring during this time, and watched the skidder drag logs across the stream bed of Stream #2 minutes before we collected the water sample.  Clearly, the high turbidity recorded at downstream sites #4 and 5 reflect the sediment stirred up during this process.  Although active logging occurred during the entire time we measured turbidity, all other measured values were far lower than this spike.
 

        The following graph, showing turbidity measurements with the two very high levels removed, demonstrates the homogeneity of these measurements - including those locations upstream of the logging.  This strongly suggests a rapid settling of the sediments stirred up by logging activities.
 

No significant changes

 The following graphs show no noticeable changes in chloride, conductivity, or temperature along the streams.

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