Table 1.

Sampling point, geographic coordinate system, and description of the major anthropogenic activities.

Sampling Point	Designation	GIS Co-Ordinates	Description of Major Activities
Chiromo Bridge/Museum Hill roundabout	S1	−1.274697, 36.811925	Upstream with learning institutions, offices, and motor vehicles traffic
John Michuki Park	S2	−1.275753, 36.817161	Upstream small businesses, shops, cottage industries such as welding, car repair/garage
Globe Cinema roundabout	S3	−1.278397, 36.820902	Middle stream with motor vehicles traffic, cottage industries such as welding, car repair/garage
Kirinyaga road	S4	−1.279823, 36.825661	Middle stream with numerous cottage industries such as paints, panel beating, car repair/garage, dyeing industries
Kariokor	S5	−1.281559, 36.832641	Middle stream, small businesses, plastic and rubber burning with numerous cottage industries such as paints, panel beating, car repair/garage, dyeing industries, textile and food vending, dumpsites, wastewater inlet streams
Gikomba	S6	−1.286105, 36.836928	Middle stream with numerous cottage industries such as paints, panel beating, car repair/garage, dyeing industries, textile and food vending, wastewater inlet streams
Juja Outering road	S7	−1.264953, 36.879202	Downstream with leaning institutions, hospitals, dumpsites, offices and motor vehicles traffic, residential area
Eastern bypass	S8	−1.245381, 36.988022	Downstream with leaning institutions, residential area