The primary sources of Nitrate in our watershed are agricultural practices such as fertilizer application and cattle grazing near creeks, and run-off from urban areas where residents use lawn chemicals. The amount contributed by these sources can be reduced with best management practices, or BMP's, which are subtle modifications that are easy to implement and often carry other advantages for landowners. Ideally, we would not measure any nitrate levels in our local creeks because even 1 ppm is more than we should measure. As nitrate levels approach 5 problems may result. The most common problem is excelleration of algal growth.
Nitrates feed algal blooms that grow to nuisance levels.
When these blooms die, they are decomposed by microbes that deplete dissolved oxygen supplies and affect aquatic life. Nitrate in the form of Nitrite can also cause a fish blood disease similar to blue baby syndrome in humans. The presence and extent of algae is of interest because it sometimes reachs nuisance levels within portions of the creek. Algal coverage data will be used to document instances of nuisance levels, and to assess the effectiveness of control measures. Previous studies have shown that the health of SLO Creek is threatened by increased temperatures, reduced flow rates, high rates of erosion and deposition, non-point source pollution, and nuisance alagal blooms.