Bookmark and Share

PAWSD deals with water quality, proposes project

It was at the end of last month that some people started to notice something in the water from Lake Hatcher provided by the Pagosa Area Water and Sanitation District water system. There was a smell, and a taste some described as “moldy” or “musty.”

According to PAWSD Special Projects Manager Renee Lewis, in late July, Lake Hatcher experienced an, “excessive algae growth event.” She noted that this is not an algae bloom, but a much less severe event.

Lewis explained that, during summer months, typically starting in the beginning of June depending on weather, PAWSD begins to test algae levels in Lake Hatcher. Throughout the summer, PAWSD continues to test the levels once a week. During this particular incident, the water algal level was tested on the second Friday in July and was reported at 50 cells per milliliter. That following Monday, the water was tested again and the levels of algae were at 500 cells per milliliter.

The reason for this exponential jump in algae, Lewis explained, was the abnormally low level of water at Lake Hatcher, lack of circulation in the lake and the hot and sunny weather being experienced during that time. In addition, Lewis explained that, due to monsoonal rains, runoff from yards in the area increased the nutrients and nitrates in the reservoir.

Once PAWSD staff discovered the higher levels of algae, they mechanically distributed a, “minute amount of copper sulfate into the reservoir,” Lewis said. She clarified that the amount of copper sulfate was less than the industry standard, so the application would not stress the fish in the lake.

“It’s a fine balance, managing a reservoir. It is its own ecosystem,” Lewis said.

The way the copper sulfate works is by attaching itself to the algae and then the algae settles out. After this, the water is filtered through the PALL filtration system at the Lake Hatcher Water Filtration Plant.

The water, she adds, is and has been safe to drink.

Lewis stated that, on some level, an excessive algae growth event occurs nearly every year, and it is not unusual for such an occurrence to happen in reservoirs. PAWSD, Lewis stated, has plans for overall changes to infrastructure composition that would, “include fairly consistent feed of fresh water through all the lakes,” and would decrease the chances of excessive algae growth. The first step will be an upgrade to the San Juan Water Treatment plant that will allow the facility to treat water from Lake Forest.

“That will then pull water through all the lakes to produce fresh water infusement to all the lakes,” Lewis said.

Next, there are plans to convert the current Snowball plant to a pump station for pumping water from the San Juan River to Village Lake, thereby adding increased fresh water to the reservoir system. A pipeline will be constructed to take the water from the station to the lake. After this is accomplished, the San Juan Water Treatment Plant will be the primary treatment facility in the district and Lake Hatcher water levels could remain higher than at present.

Right now, these upgrades are planned to be finished in the next three to four years.

In a letter to the editor printed last week, Lisa Kelly expressed concerns regarding the state of PAWSD drinking water. She cited a U.S. Geological Survey report on a study on Midwestern lakes in which lead scientist on the study, Dr. Jennifer Graham, states that, “While taste-and-odor compounds are not toxic, these pungent compounds were always found with cyanotoxins.” In the report, it should be noted, Graham’s quote continues to specify that this was the case, “in the blooms sampled.”

Lewis addressed this concern by pointing to the USGS Toxic Substances Hydrology Program issued in an article titled, “Algal Blooms Consistently Produce Complex Mixtures of Cyanotoxins and Co-Occur with Taste-and-Odor Causing Compounds in 23 Midwestern Lakes: Frequently Asked Questions.” That article describes cyanobacteria, commonly referred to as blue-green algae, as a, “natural part of aquatic ecosystems” that commonly occurs at low abundances. The report continues to state that some cyanobacteria can produce cyanotoxins which can be harmful to humans and animals. Cyanobacteria may also produce “earthy or musty taste and odor compounds,” which are not toxic.

Kelly also sent an e-mail to friends and members of the media stating that PAWSD has agreed to a short-term monitoring program for cyanotoxins in Lake Hatcher, and that she was pushing for this to be done to all water sources on a permanent basis. Lewis clarified that since excessive algae growth events are singular events, PAWSD does test for cyanotoxins during and after the events, but at no other time.

blog comments powered by Disqus