Chippewa River E. coli spikes at confluence

Area of impact at north branch near park

Levels of E. coli in the Chippewa jumped to double the state’s safety standard in the latest testing by the Saginaw Chippewa Indian Tribe where the river meets its north branch just downstream from Meridian Park.

Both the daily mean of 652.3 and the 30-day mean of 485.73 more than double state safety standards of 300 and 130, respectively. A mean — more commonly known as average — is calculated by adding all of the test results and dividing them by the number of times tested. The testing

was conducted on June 22.

The results of the testing are expressed as colonyforming units per 100 milliliters of water. It is an estimation of the number of viable bacteria.

A result of higher in either category means people in and around the river are advised to only have partial contact with the water.

Downstream in Chipp-awaters park, levels fell to a quarter of the daily mean at 159.7, below the state standard of 300. The 30-day level stood at 154.95, which is above the state’s safety standard.

By the time the river reached its next testing point at Chippewa Road, E. coli levels fell below both safety standards, with a daily mean of 116.3 and a 30-day mean of 101.9.

All but one test results from the river upstream from the Chippewa’s confluence with its north branch were below state safety standards.

The outlier was the 30day mean at the Coldwater Road bridge of 152.35. The daily mean there was 83.3.

Testing in Merdian Park itself produced a daily mean of 76 and a 30-day mean of 94.68. At School Road, the remaining testing site, the daily mean was 16.7 and the 30-day mean was 22.6.

ERIC BAERREN — MORNING SUN The swimming area at Mt. Pleasant’s Millpond Park was empty Thursday afternoon. E. coli levels in the Chippewa River spiked where it meets the North Branch of the river, but fell by the time the water reached Mt. Pleasant.