The Manoa Stream starts in some pristine areas deep in the valley.
But from Mauka to Makai, lots of things from people’s yards and all kinds of neighborhoods eventually empties into the Ala Wai canal.
Sampling in the area found some 20 different types of pesticides in the water.
Some are linked to chemicals used to treat termites that are no longer on the market and some to the common weed killer "Roundup. "
"There were also a number of pesticides used in everyone's home every day. There were things like roach killers, ant traps and things used on flea collars," said Phoneix Grange of the state health department’s Hazardous Evaluation and Response Office.
The good news is that none of the chemicals exceeded drinking waters standards.
"If it is below drinking water standards you can be comfortable that swimming and playing the waters and fishing in those areas is going to be OK," said Grange.
Waikele stream is the other area of concern on Oahu.
Some chemicals are believed to be from the high concentration of area golf courses and the urban areas that were once large agricultural fields.
But there are some pesticides that are not registered for use in Hawaii
and a fungicide that was also taken off the market is still showing up on Oahu.
They found different patterns on different islands but no real blockbusters when it came to small farms versus large farm use of pesticides.
"The place we saw the most agricultural chemicals from seed corn was on Kauai and that was partly of the nature of a place we chose because there were ditches immediately adjacent to fields rather than miles upstream," said Grange.
But again officials stress there were no levels requiring regulatory action.
"It just indicates to us that industry as a whole, and we are talking about large ag farmers and pest control industry, are following the labels pretty much," said Thomas Matsuda.
Nonetheless, agriculture officials plan to keep up routine inspections to keep everyone on their toes.
There were two compounds found in streams higher than should be that could affect aquatic life.
Officials say the data is a wakeup call for everyone to be careful about the chemicals we use and how to properly dispose of them.