Table 1.

Description of the Rio Grande de Arecibo watershed study sites

Site	Location	Altitude (m)	Landscape feature			Presumed primary fecal contamination sourcea
			Forestland	Grassland	Human density
1	Lago Garza, Guilarte Forest	736	High	Scarce	Low	Some waterfowl (heron)
2	Rio Vaca in Guilarte Forest	542	High	Scarce	Low	Septic tanks, some poultry
3	Upstream from Adjuntas WWTPb, Cidra River	510	Low	Scarce	Medium	Urban runoff, some waterfowl
4	Downstream from Adjuntas WWTP, Cidra River	510	Low	Scarce	Medium	Sewage, some poultry
5	Beginning of Arecibo River	450	Medium	Low	Medium	Urban runoff, septic tanks, some poultry
6	Upstream from Utuado WWTP	376	Low	Medium	High	Cattle, septic tanks
7	Downstream from Utuado WWTP	376	Low	Low	High	Sewage, some cattle and poultry, iguanas
8	Mouth of Arecibo River	Sea level	Low	High	High	Cattle, urban runoff
9	Criminales River	276	Medium	Medium	Medium	Cattle, urban runoff and septic tanks, some poultry
10	Downstream from Jayuya WWTP	460	High	Medium	Low	Sewage, cattle, some poultry

^aThere is historical knowledge that host animals are present at these sites for a significant part of the year.

^bWWTP, wastewater treatment plant.