Sampling the Santa by Colin

The Rio Santa sure looks different in the dry season than during the wet season. In March it was a angry torrent as far upriver as Catac, where it seemed intent on ripping out bridge pilings and dragging weak and inexperienced discharge measurers into its swirling depths. In Huaraz today, the Santa languidly slides down its channel, as if there was no hurry to reach the Pacific, which of course there isn’t, because the majority of water in the dry season is diverted into the irrigation canals of Chavimochic and Chinecas to grow the asparagus that you buy at the grocery store back in Ohio or wherever else.

No, in the dry season the Rio Santa stands out not for its current, but for its trash. In many riverfront communities the Santa is viewed as an all in one trash, recycling, and compost receptacle. Anything you dump in the river, you’re not likely to see again. If you miss the river, well, the raging flows of the rainy season will eventually carry it away. On this occasion, our sampling of the river did not concern trash, though the garbage could not be ignored. We were headed to the river just north of Huaraz to test the waters for trace metals, which don’t have the visibility of say, old shoes and styrofoam, but represent a significant hidden danger to those who use the water.

Trace metals or not, we first had to hike along the trash-strewn riverbed to our sampling site. Several trace metals including arsenic have been found in dangerous concentrations in different reaches of the Rio Santa. The Rio Santa watershed contains both natural and industrial sources of these contaminants. If you watch closely while driving up the Callejon de Huaylas, you will spot more than one mound of mine tailings in the floodplain, not to mention in higher parts of the watershed. The town of Ticapampa, for instance, coexists with two massive, eroding mounds mine tailings. A stream even flows between the two, carrying anything that leaches out of the mound directly to the Rio Santa. Meanwhile, on the other side of the mounds runs the highway, and directly across that are homes and businesses.

Back at our smelly site on the Santa, we spent six hours working, collecting the usual suite of samples for trace metals in the water, suspended sediment, and riverbed each hour. Results won’t be analyzed for a while, but the idea of this sampling was to see if trace metal concentrations in the water and sediments vary significantly throughout the day in the same location. For the sake of our sampling approach, I would hope that changes are minimal, but different results would be interesting.

In the end, our day working in the field was more like a day at the beach… a really disgusting beach, but a beach all the same. Our sampling went smoothly and we spent the time in between sunning ourselves on boulders and watching onions and plastic bags float by in the current. On our way back to the road, I spotted a dump truck disgorging a load of trash down the riverbank next to the bridge. I wonder if they appreciate the trash of Huaraz downriver in Carhuaz, Yungay, and Caraz? People in communities along the Rio Santa use its water for many purposes, and the cleanliness of the water should not be ignored if public health is regarded as an important priority.