Originally published on February 15, 2024
The shallow waters of Lake DeWeese Reservoir froze solid enough for locals to partake in an ice fishing tournament held last January, but in the summer, the same locals will await the announcement that the innocent-looking waters have become too toxic to touch by any member of the mammalian persuasion. Year after year, an ancient water organism with the ability to turn light and available nutrients in the water into food for the organism grows in DeWeese. This generally benign process of Cyanobacteria growth only becomes toxic for reasons not completely understood by scientists, but the layman knows that it happens every year in the waters of DeWeese; it is only a question of when.
The common name for the toxic bacterial blooms is Blue-Green Algae, but this name is a misnomer as Cyanobacteria are not part of the more complex organisms that make up the algae species. In addition, Cyanobacteria are one of the most numerous taxonomic groups of organisms ever to have existed on Earth and are thought to be one of the first organisms ever to have produced oxygen as a biproduct of photosynthesis. The reality is that most Cyanobacteria are harmless to mammals and play an important role in all life. But the problem is that if the conditions are right, some Cyanobacteria can produce toxins that are powerful enough to cause rashes on the skin of humans, and in other cases, kill dogs that swim or ingest the water filled with what is called âPhycotoxins.â
On February 13, five members of the Colorado Department of Parks and Wildlife (CPW) held an informational meeting that was attended by around 50 members of the Custer County public. Locals wanted answers on how to deal with the toxic algae for a variety of reasons. For some, it was the obvious safety problem of having water too toxic to touch. But for others, the problem is much more complex as the sometimes toxic waters of DeWeese mean that the costs to build a new wastewater treatment plant that serves the towns of Westcliffe and Silver Cliff may prove to be impossible moving forward, threatening the economic existence of the towns.
While the presentation was detailed and professional, the feeling that more questions had been raised than were answered was palpable as the public headed home in the moonless dark.
An artificial lake
What was missing from the discussion was the context of how the lake itself came into existence. While the history of DeWeese was touched on in the presentation, the real question about the algae stems from the fact that manmade bodies of water always have problems when that water interacts with the surrounding environment. The Silver Cliff Rustler in July 1905 called it the âDeWeese-Dye artificial lake.â
The dam that formed the lake was originally constructed in 1902 and is still owned and maintained by the DeWeese-Dye Ditch and Reservoir Company. According to the company âIn 1896, Dall DeWeese and C.R.C. Dye incorporated the DeWeese-Dye Ditch and Reservoir Company to bring water from Grape Creek to the 1,500 acres of land they were developing with 200,000 fruit trees and 500,000 shade trees in Lincoln Park, just south of Cañon City, Colorado. Today, water from DeWeese-Dye Ditch and Reservoir Company continues to irrigate lands and growers in Lincoln Park serving properties located below DeWeese Reservoir below the ditch from Grape Creek Drive to Brookside.â Originally, DeWeese wanted to name the Lincoln Park area âFruitland.â
Local Conservation Board President Robert Miller in an email to this author perhaps asked the question that has never really been addressed. âThe reservoir was built to store water for the specific purpose of irrigation south of the Arkansas in the Lincoln Park areaâŠthe location and design were never considered recreation.â So, is the Cyanobacteria a problem when considering the actual reason the dam was really constructed? The easiest way to fix the problem is tear down the dam and perhaps allow beavers to return to the area. Cyanobacteria cannot grow in water that moves more and gets more oxygen; this is why beaver dams in water that has high amounts of nutrients donât experience toxic blooms. But that would harm the company who owns the dam and the other organizations that use the lake for water storage. So perhaps the idea that recreation should be a priority needs to be addressed.
The costs to the city
Nutrients running in water is natural. The ancient cities of the Fertile Crescent relied on nutrients running into rivers in the spring and flowing onto irrigation crop lands. In modern times, the nutrients that fuel toxic blooms are nitrogen and phosphorous. As the CPW officials pointed out, there are three primary sources of these two nutrients: Herbivores like cattle, artificial fertilizers, and wastewater. Because Round Mountain Water and Sanitation District inject treated water into the ground, it is unlikely that city wastewater is the problem for increased nutrients. Herbivores have been here in great numbers before settlers arrived, but the modern practice of raking fields to break up the cow patties does increase nutrient load in streams. Lastly, hay production on the Valley floor does use fertilizers in the spring which leach into the stream.
The issue is that even if the fertilizers were addressed, it is not clear that the toxic blooms would end. The natural nutrients plus those of cattle might be enough to keep the toxic blooms alive in the artificial lake environment. In 2022, the price of fertilizers was so high, that hay producers cut back on fertilizers and while it took longer for the bloom to show up, eventually it still did.
Regardless of what happens at the lake, the state has done tests and stated that Grape Creek is an impaired waterway due to the high nutrient load, which increases the costs of a new wastewater treatment plant that will return water to the creek instead of injecting into the ground as it was done for the past 40 years.
In the end, it is clear that the source of the nutrient load is not fully understood, and until that happens, it is unlikely any action will be taken locally that will help eliminate the toxic blooms that are sure to return to DeWeese this summer.
â Jordan Hedberg
