What We Know About the Water Quality in Polk County

About ten years ago, much community attention and public dialogue was swirling around the topic of Iowa’s water quality. There was speculation related to nitrate levels or other contaminants, and even the degree to which and how these things may be harmful. But the true reality was, there was very little reliable, consistent data to inform the conversation, much less practice and policy. Polk County Conservation (PCC) launched its water quality monitoring program in 2015 to fill the data gap.

Starting with 32 sites across the county and since growing to 70 sites, PCC’s staff, city partners, and volunteers have been testing water quality twice a month to create a better collection of data on the health of the waterways.

Now, with ten years of data, scientists and conservationists are much better equipped to talk about and make decisions related to Polk County’s creeks and rivers. There is some good news. For example, along Beaver Creek through Johnston, 71% of the 647 assessments done had pretty clear water (nearly a foot of water clarity). That number for Fourmile Creek was even better, 87% of the 1,784 assessments. And dissolved oxygen levels, a good indicator of ecological health, had under 10% of the assessments in what is considered harmful for fish (less than 6mg/L).

 

There are challenges. At certain times of the year, some nutrients are abnormally high. For example, nitrates tend to be high in rural areas during the spring. Nitrates occur naturally and are an essential nutrient for a healthy ecosystem, but high levels recorded indicate excessive human sources. That is a concern for water treatment plants that need to ensure drinking water stays within standards for consumption. On the other hand, high nitrate levels have little-to-no impact on recreation in waterways. You can fish, boat, and swim with confidence, knowing nitrates are not a threat.

In urban areas, PCC’s tests have shown high levels of chloride in waterways at unexpected times of the year. High chloride levels typically occur in winter from use of road salts. Unfortunately, 06 results are also showing elevated levels in summer. This indicates that road salts are not the sole source of this contaminant, like previously suspected. This may indicate a buildup of salts in the soil, contaminated groundwater, or leaking septic or sewage pipes. Much more research is needed to identify the source. Regardless of origin, high chloride levels are harmful for the aquatic life in our waterways that are used to living in fresh water.

In addition to establishing long term trends in what comprises Polk County’s water, the program also functions to minimize the impact of any critical incidents. When a field monitor observes something alarming in a waterway they report it to PCC. Ecologist Amanda Brown calls this the “red flag network.” If the critical incident is on county land, a staff member goes to investigate. If it is from city land, the local officials are alerted of the problem and handle it themselves. If the problem is deemed an “immediate threat,” the Department of Natural Resources is contacted.

PCC water quality coordinator Ginny Malcomson recalled an event several years ago when a few dedicated water monitors at Easter Lake realized there was much more water in the creek than there should have been. PCC reported it to the city of Des Moines, who realized there had been a water main break upstream of the testing site. What We Know About the Water Quality in Polk County About ten years ago, much community attention and public dialogue was swirling around the topic of Iowa’s water quality. There was speculation related to nitrate levels or other contaminants, and even the degree to which and how these things may be harmful. But the true reality was, there was very little reliable, consistent data to inform the conversation, much less practice and policy. Polk County Conservation (PCC) launched its water quality monitoring program in 2015 to fill the data gap. “They were able to stop a water main break just because they were really familiar with the site and they knew that there should not be that kind of water coming down after not having any rain,” said Malcomson.

The PCC program has been critical in helping Iowans get a better understanding about the state of water quality in Polk County. In addition to the resulting data being more widely publicized and available to decision makers, public involvement in ongoing monitoring and bi-annual snapshot events has created a small army of passionate water quality advocates. To Brown, having an informed understanding of the situation is critical to bringing people together to create solutions. “We need to realize that we have an issue, and we need to work together to try to figure it out. That’s my biggest hope,” she said.