Phosphorus Reductions in the James River and Table Rock Lake


A Brief History of Water Quality in Table Rock Lake

Table Rock Lake has long been a popular destination, offering a variety of recreational opportunities. One aspect of the lake that helped draw both those within and outside of the state back year after year was the clear, blue water. Water clarity in Table Rock Lake has always been exceptional, with transparency readings that are over 3 times deeper than the Missouri average.

In 1995 University of Missouri researchers identified a trend of decreasing water clarity near Table Rock Dam. Decreased water clarity was attributed to an increase in the amount of algae in the lake, which was directly linked to increases in the plant nutrient phosphorus. While phosphorus is a naturally occurring element, human activities lead to increased amounts within our rivers and lakes. Prior to the 1995 finding, the human population in Table Rock Lake’s watershed had increased considerably, translating to more phosphorus entering the lake. During this period there was also an increase in livestock agriculture (e.g. poultry) within the watershed, another source of nutrients.

Algae bloom on the James River

Aerial photo of 1999 algae bloom in the James River arm of Table Rock Lake (Missouri DNR photo)

Citizen concern over changes in water quality in the lake, especially in the James River Arm, led to the formation of groups such as the James River Basin Partnership and Table Rock Lake Water Quality, Inc. These groups provided a focus on the issues and a voice for the growing concerns. In 1998 and 1999 two large algal blooms occurred on Table Rock Lake, with one of them being followed by a fish kill. These events occurred during peak tourist season, giving the region a glimpse of Table Rock Lake’s future if changes within the watershed were not made.

In 1999 Missouri’s Clean Water Commission passed regulation limiting the amount of phosphorus allowed in the outflows of sewage treatment plants located in the Missouri portion of Table Rock Lake’s watershed. Springfield’s Southwest Treatment Plant started meeting the required phosphorus reductions in March of 2001, two years earlier than mandated.

The following series of graphs show how the reduction in phosphorus output at the Southwest Treatment Plant have impacted the whole James River Basin. Phosphorus concentrations at seven sites in the basin are presented with a comparison of values from before and after the treatment plant upgrade. The response of algal levels and water clarity to phosphorus reduction at four sites in the James River Arm of Table Rock will also be reviewed.


Printer-Friendly Version Here

Brought to you by the Lakes of Missouri Volunteer Program