Here we have chlorophyll concentration in ppb is along the y-axis and year along the x-axis, depicting mean annual chlorophyll concentrations in ppb at site 1 from 1976 to 2005. This graph shows that historical mean chlorophyll concentrations have remained below 10 ppb. This is good news because other lakes with annual algal blooms, like China Lake, have much higher chlorophyll-a concentrations than this, which indicates higher productivity levels. However, we do see a trend in increasing chlorophyll-a levels, which is something to be concerned about, and, as we will see later, fits with the transparency data.