Results of a Surface Water and Groundwater Quality Survey in Northeastern Ecuador

The Oriente region of Ecuador, located in the northeastern portion of the country, has been under active oil production since the mid-1960s, when the first oil well began producing oil in Lago Agrio (Sour Lake). Since then, hundreds of wells have been drilled and numerous production stations have been built, many in close proximity to streams and rivers. Over time, encouraged by government policies, the population of the region grew significantly and the new residents settled near active and former oil exploration and production sites. Many of these new residents used and continue to use water from hand-dug wells and streams as a source of water for consumption and domestic use. 

 

The scope of this water quality survey consisted of collecting surface water samples from streams, and groundwater samples from private wells and from temporary wells installed using direct-push methods. Duplicate samples were collected at appropriate sampling intervals for QA/QC purposes. Streams and private wells were selected based on their proximity to 13 active or former petroleum exploration and production sites in the Sucumbíos and Orellana provinces, near the border between Ecuador and Colombia. Groundwater samples obtained using direct-push methods were collected from locations that were adjacent to former oil exploration pits or sites, to assess possible migration of dissolved petroleum constituents in groundwater. Samples were analyzed at U.S.-based laboratory for BTEX, PAHs, TPH‑DRO, TPH‑GRO, and selected heavy metals, and at a local laboratory for total and fecal coliforms.

 

Laboratory results indicate that the surface water and groundwater sampled in this survey are not currently adversely affected by active or former petroleum exploration and production sites. However, results for both surface and groundwater samples indicate widespread adverse impacts from total and fecal coliform, which likely result from poor sanitary and well construction practices.