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Hidden in the water

A child’s quick eyes and soft footfall helped her catch (and release) this American toad at Big Rock Park.

In May, the final 2023 spring foray lead by biologist Nicole Palenski Lander and chemist Cathy Haustein ventured forth into Big Rock Park. The group looked for the hidden treasure of reptiles and amphibians and tested the water in the park along the way. None of the adults in the cheerful assembly saw a snake, salamander, frog, or toad that day but a child, looking independently, caught the American toad shown above.

Leopard frogs are experts at hiding. According to biologist Lander, “The best way to find a frog is to be still and listen. We may have just missed them as they like to hide. But the challenge of finding them makes it fun to go back again and see what you may find the next time!”

The timing for coming upon a snake wasn’t quite right either—they come out in the afternoon, especially when sunny, to bask after eating. The sun helps them digest their meals! This expedition began in the morning, when snakes are hunting.

The group turned their attention to something frequently on the minds of Iowans--water quality.

Water is one of an ecosystem’s greatest treasures. Local children wade in the water at Big Rock Park, and it provides a habitat for aquatic species. In many cases, an urban park such as ours provides a source of clean water, acting as a purifier for various lawn chemicals which might drain into the watershed.

According to the Big Rock Park Master Plan 2000, prepared by Dunbar/Jones Partnership, the water in Big Rock Park comes from Thunder Creek and other tributaries.

The park is accessed by a gravel driveway and a little used road going to a former sewer plant in the northeast section of the park. The water flows mainly from the south and west of Pella, moving northeast. Runoff from Pella (to the south of the creek) is sent on to the creek.

According to Jeanette Vaughn, Pella’s Community Services Director, storm water run-off along with run-off from nearby homes and farms contribute to the water in the creek. With the drought, she assumes that much of what has been observed in the creek comes from storm water since yards and fields will rapidly soak up rainfall.

What did the group find?

An overall measurement of what’s in the water, both good and bad, is the amount of Total Dissolved Solids. This test, done using a handheld meter, measures dissolved substances in water, particularly dissolved minerals. It doesn’t distinguish between healthy and unhealthy substances. Big Rock Park water has a variable concentration of dissolved solids as would be found in hard water or average tap water. The TDS levels were around 200 parts per million,, as measured with a handheld meter, as shown below.

Several tests were done using indicator paper and these found traces of fertilizer in the creek.

Nitrite and Nitrate come from fertilizers , decaying plants, and sewage/manure. They can stimulate the growth of bacteria and algae and cause harm to human health, including cancer and problems with oxygenation of blood, blue baby syndrome, shortness of breath, nausea, dizziness. These pollutants were found primarily near the entrance to the park.

Phosphate is a nutrient which encourages algae growth and is introduced from fertilizer. 0.005 ppm or less is considered healthy. Phosphate was measured with indicator paper. Phosphate pollution was found. Phosphate is a sign of “unbalanced agriculture” and can decrease the oxygen levels in water. This was significant at the entrance on May 20, 2023 and found throughout the park’s water.

Big Rock Park water showed signs of lead contamination, most likely from corroded leaky plumbing. Denny Buyert of the City of Pella says that lead is ubiquitous in our area and can come from old service lines to older homes in Pella, lead paint, and even car batteries that have been improperly disposed of, for example, tossed in a ditch. Politicians make fun of scientists who recommend that smaller bodies of water be regulated but unscrupulous people can and do toss dangerous things into ditches and puddles. Lead was found throughout the park water, especially at the site nearest to the Big Rock, the water coming from the south and west, from Pella.

Dissolved oxygen levels, needed for aquatic animal life, were healthy at all points along the creek except the entrance, where organic matter accumulates at the entrance because of restricted water flow. The dissolved oxygen probe found the levels at the entrance were okay for life but would not encourage spawning of fish. Oxygen is introduced into water by turbulence such as rushing over barriers. Stagnation, dead matter, and heat all reduce the oxygen and can result in fish kills.

Surprisingly, pesticides were not found in the water. There was perhaps a trace near the site closest to the rock, as shown by a paper indicator test.

Water testing products have gone mainstream in the last few years. They are readily available for sale and are portable and easy to use.

Even kids can test water! These boys are showing some of the tools needed to test water at the park.

In summary, Big Rock Park Creek is affected strongly by the surrounding community of Pella. What goes on lawns and roads tends to show up in the surface water. Yes, for now, the park water can handle and recover from Pella’s storm water run-off.. But people of Pella should show it some love! Do you really need all of that lawn fertilizer?

Water is a critical resource and we need to take care of it and appreciate it, before it becomes harder to find than a Leopard frog in the park.

The Friends of Big Rock Park is grateful for a supporting grant from the Pella Community Foundation and the Marion County Community Foundation


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