Stephanie Castle
Masters Student in Ecology
UC Davis

We finally went out on the lake with our wetland activity group, and one of the things that struck me during our tour of the wetlands around the lake was “las pilas”. Lake Atitlan used to be a wonderfully clean and clear lake, but over recent years, increased input of nutrients to the lake has resulted in some concerning blooms of a cyanobacteria Lyngbya. Among other things, laundry soaps and detergents represent a major source of nutrients into the lake. A large proportion of the women around the lake wash their clothes right on the shore using detergents loaded with phosphates which contribute to eutrophication of the lake. Looking at the places where these women wash clothes, you can see clouds of detergent floating in the water behind them as well as a virtual forest of submersed aquatic species (Hydrilla, Egeria), algae and Lyngbya.

 In attempts to remediate this issue, the Rotary Club of East Guatemala installed some community wash basins called “pilas”. The pilas allow the women to wash their clothes outside of the lake, then the effluent from the pilas is routed through a treatment wetland which, theoretically should process a large portion of the nutrients before they reach the lake, thereby minimizing the nutrient load from wash water into the lake. However, as we walk up the road toward the pilas, what do we see? Women washing their clothes in the lake!!!

We met a guy who lives near the pilas and he explained that the older women don’t like using the pilas and avoid them because they prefer their old habit of washing in the lake. He also mentioned that with the fairly clean water running into the pilas, people wanted to be able to bathe while they wash in the pilas, but because it is to public a place to bathe, they again prefer the lake. Additionally, the wetlands which are supposed to act as bio filters for the nutrients leaving the pilas aren’t acting as efficiently as one would hope. When you look at the plants inside the wetland, there are visibly miserable. Plants like to have a certain balance of nitrogen (N) in proportion to phosphorus (P). But, because the laundry soaps have so much P, the plants are overloaded with P, and don’t have enough N to grow and be happy J. The pilas in San Lucas are a really good example of a practical solution with promise for managing effluent into the lake and perhaps, with a few tweaks, it true potential may be realized!! Very exciting.