Water Quality In Johnston

In 2013, the City of Johnston began a water quality monitoring program using funding from the Johnston Stormwater Utility fee which is collected from property owners each month. To begin monitoring the water, the City contracted with the University of Iowa Hygienic Laboratory (UHL) to collect and analyze water quality samples from ten locations across the city (PDF). This sampling is scheduled to occur three times each year, in April, July and October so the impacts of various weather conditions and their impacts on water quality can be monitored over time.

The monitoring is conducted by UHL staff who visit the designated sites, and if flowing water is present, water samples are collected and analyzed. Samples are analyzed for pH levels, turbidity (water clarity), and levels of E. coli bacteria, nitrate, total phosphorus, and total suspended solids. A summary of each testing parameter and why it’s tested is available here (PDF). UHL staff also photographs the site at the time of the visit and provides lab analysis results to the City. These results are then reviewed for trends. It is also anticipated that potential contamination sources can be identified and the effectiveness of water quality practices can be determined over time.

The following reports summarize the collections completed to date:

By month summary reports

Yearly summary reports

Water quality monitoring is an important process to improve the water quality flowing in and through Johnston, especially since the streams that flow through Johnston ultimately drain to the Des Moines River, which borders the city to the east and is one of the main sources of drinking water for the entire Des Moines metro area. Beaver Creek, the major stream that flows through Johnston before draining to the Des Moines River, is designated by the state as an A3 stream (Children’s Recreational Use) due to its proximity to a number of residential properties and public park and trail areas and is often used for recreational purposes such as kayaking. By collecting this data, it allows the City to identify possible sources of pollution and take corrective action, if possible, to keep this water safe.

In an effort to improve the frequency of water quality monitoring in the Beaver Creek watershed, the City of Johnston in 2017 began participation in the Polk County Water Quality Monitoring Program (PCWQMP) which is led by Polk County Conservation. The City of Johnston has had two employees trained in the water quality monitoring procedures utilized by this program and these employees have begun bi-monthly visits to Little Beaver Creek to monitor the quality of the water. These samples are taken at the same time as other samples are taken throughout Polk County. As more site visits are completed a baseline will begin to be established allowing for reporting of the ongoing health of the Little Beaver Creek watershed. Additional sites may be added throughout the City of Johnston in the future. For more information about the County’s monitoring program, please visit Polk County Conservation.

Questions about the city’s water quality monitoring program may be directed to David Wilwerding, Community Development Director. He can be reached at 515.727.7775 or by e-mail.