Keeping Arlington's Waterways Safe, Clean For Public Use

ARLINGTON, MA — Ensuring clean and safe swimming water in a public pool or pond requires vigilance from staff and a strict adherence to state water-testing guidelines. In a public swimming pool, that typically means the water is tested up to four times per day for chlorine and pH levels. In a pond, that means weekly third-party testing for spikes in levels of bacteria, such as E. coli.

In the Arlington Reservoir — a public beach that is chlorinated — Arlington Acting Parks and Recreation Director Stacey Mulroy has the challenging aspects of both maintaining a pool and a pond. The reservoir, which has a swimming area closed off from the full body of water, is tested four times per day for chlorine and pH, plus checked for bacteria levels once per week.

"It's not as difficult as it might sound like," she assured. "Because we close it off from the rest of the reservoir it is not as many gallons. If we were trying to maintain levels for the entire reservoir, it would be next to impossible."

The Centers for Disease Control caused quite a stir three weeks ago when it reported an uptick in cryptosporidiosis — a parasite-borne illness that can cause bouts of "profuse, watery diarrhea" — being contracted in public swimming areas. The cause of the disease is often people going swimming too soon after being sick and spreading the illness to those who swallow infected water. The CDC report said crypto outbreaks increased annually at an average rate of 13 percent.

While Mulroy said there has been no evidence in crypto in Arlington this year, the reservoir was closed once this season due to a child fecal incident.

"We just ask that parents keep their kids hydrated," she said. "One of the issues we have when it is super hot in the summer is that the kids go running to the slushy machine. When you do that, and you don't have enough food or water in your system, it wreaks havoc on the body. That's when thing go haywire. We ask that parents feed the children a good, healthy lunch with lots of water."

Lifeguards are on duty at the reservoir to keep an eye out for any issues, but the natural bottom of the reservoir can make any accidents a bit more difficult to detect than would be the case in a swimming pool with a title or concrete base.

"A lot of parents are good and will self-report, so that is helpful," Mulroy said. "We don't have a ton of food so it's not too bad. We actually see less problems with kids in diapers than we do in that 5- to 7-year-old range."

The CDC report recommends not swimming, or letting kids swim, until two weeks after diarrhea symptoms have subsided, not swallowing water in swimming areas and washing hands with soap and water after coming into contact with animals or animal waste — alcohol-based sanitizers do not work effectively on crypto.

Since Spy Pond in Arlington is not a swimming beach, that water is not tested for bacteria. The pond was closed to recreation last Friday, however, for a scheduled treatment for "invasive species." Environmental planner Emily Sullivan said an herbicide called Tribune was used for Friday's treatment.

"The town schedules treatments on an as-needed basis," she said. "This pond closure is not abnormal, since the pond is treated regularly."

Sullivan said the town contracted SOLitutde Lake Management last spring to lay out a plan for treatments and pond management in conjunction with the observations with the Spy Pond Committee.

She suggested ways the public can help to improve the quality of Spy Pond: "Reduce or stop the use of fertilizers on lawns surrounding the pond. Storm water runoff carries fertilizer into the pond, which promotes the growth of algae and invasive aquatic plants.

"For those properties immediately adjacent to the pond, plant native species along the property's edge to create a buffer between homes and the pond. Respect the pond's banks and follow formal paths around the pond. When park users go off path, they erode the pond banks and cause sedimentation into the water.

"Wash off any kayaks, paddle boards, or canoes before and after using them in Spy Pond. Kayaks, paddle boards, and canoes can transport invasive aquatic species, particularly if they are used at multiple water bodies."