The threshold concentration of nitrate in water supplies to protect against methemoglobinemia is 10 mg/L. Methethemoglobinemia is a potentially fatal disease, primarily in infants. High concentration of nitrates is suspected of causing miscarriages. (fn 3) Nitrates also cause eutrofication of streams, but no threshold for nitrate concentration as it relates to eutrification has been established. (fn 1)

The levels of nitrate in the water were highest where the stream entered the golf course and decreased  as the stream went through the golf course. This suggests that the major source of the nitrate is not the golf course. Because the area around the course is residential and many residents use lawn maintenance companies, it may be that higher amounts of nitrates are due to residential use of  fertilizers. (fn 4)

To manage nitrate levels, several techniques can be used . One in particular in use at the golf course is the pond which is an aqua culture system. (fn 2) The pond is shallow and has supplemental aeration. It does not, however, have floating aquatic plants to take up nutrients. There is a large quantity of algae present and an extremely large population of snails  which scavenge. It is not known whether periodic harvesting takes place. Runoff is directed to the stream as opposed to being diverted. The aqua culture system is effective causing a decrease in the nitrate concentration of 2.5 to 3.5 mg/L from inlet to outlet, or 70% - 83%.