Lodi Lake's visible water quality has improved by nearly 3 feet during the past year, says Kathy Grant, an active Lodi Lake docent and storm drain detective for the city of Lodi.
However, upstream on the Mokelumne River toward Woodbridge Dam, the water clarity isn't as good due to boating and water skiing on the river, Grant said.
Water clarity can be a measurement of healthy or unhealthy water, Grant said. Lodi's stormwater, or street runoff in the rainy season runoff, or landscape runoff drains untreated into Lodi Lake, the Mokelumne River or a local water body.
Participants used a Secchi Disk Dip-In, an 8-inch metal disk with alternating black and white quadrants, and lowered it into any lake, river, stream or body of water until it disappears. Grant said.
The depth that the disk disappears is carefully noted, she said. The depth of disappearance, called the Secchi depth measurement, measures the transparency, or clarity, of the upper water column, she said.
Lodi's measurements were taken Thursday at three sites on July 17, two of them at Lodi Lake and one was on the Mokelumne River, just upstream of Woodbridge Dam.
Grant says that lack of boating and swimming in Lodi Lake contributed to the lake's water clarity. Murkiness in the river was likely due to heavy jet-skiing and boating in the area, she added. More plant life grew on the bottom of the lake, perhaps caused by higher water temperatures, Grant said.
Detailed data will be posted on the city of Lodi's Web site, www.lodi.gov. click onto "storm drain detectives."