China Lake:  Damaging the Water Supply

A proposal that would have charged some central Maine water utility customers an extra fee to help pay for efforts to restore China Lake is dead in the water.  A legislative committee recently voted down the bill that would have added a $5-per-year surcharge to the bills of each Kennebec Water District meter customer for 15 years. The plan was to let the town of China use the money to fund projects that would improve the quality of China Lake, which is the source of the district’s water.

China Lake’s water quality took a nosedive in the 1980s when an increase in residential development created more runoff into the lake, contaminating it with phosphorous. Around that time, algae blooms increased and the U.S. Environmental Protection Agency deemed the lake an “impaired water body.”

China Lake in China and Vassalboro, Maine, covers 3,937 surface acres with its two basins. The circular west basin is relatively deep with a maximum depth of 85 feet and an average depth of 33 feet. The well-forested Bradley Island is the only island in this basin. Largely undeveloped, the shoreline of the west basin is primarily owned by the Kennebec Water District.

In Maine, lakes located in more highly developed watersheds have higher total phosphorus levels than lakes located in less developed watersheds. Phosphorus entering lakes from erosion runoff increases five to ten times when natural watersheds are converted for commercial and agricultural uses. Increased phosphorus loading potentially results in algal blooms, which turn lakes green and are associated with foul odors and bad tasting water. Repeated algal blooms, and the associated decrease in dissolved oxygen, may result in fish kills and can drastically affect the deep, cold-water fisheries.

The first recorded algal bloom on China Lake occurred in 1983. MDEP now lists China Lake as a lake that frequently blooms. China Lake typically blooms three times, once each in the spring, summer, and fall. The spring and fall blooms most likely the result of turnover redistributing phosphorus and dissolved oxygen within the lake. The phosphorus brought to the surface becomes available for use by primary producers and results in an algal bloom.

Several treatments exist to combat total phosphorus concentrations in lakes. One treatment option involves applying alum to a lake. The alum prevents phosphorus release from the sediment, preventing internal phosphorus loading. An alum treatment was applied to Threemile Pond in 1988 to prevent internal loading of phosphorus. This program appeared to be successful and China Lake was set to be treated next. However, in 1994, Threemile Pond bloomed again. Rather than invest in a treatment that might not work, an alum treatment feasibility study was conducted to determine if the treatment would succeed on China Lake.

Study results indicated that internal loading accounts for three times as much phosphorus in the lake as external sources. It was thought that at best, the treatment would prevent algal blooms in the China Basin for eight years. Since the treatment was going to cost $1 million and did not guarantee success, MDEP did not recommend an alum treatment for China Lake.

Local communities have taken many innovative steps to improve the water quality of China Lake. The China Region Lakes Alliance and China Lake Friends work to raise awareness of issues relevant to water quality and organize remediation actions. Federal funding in the form of a Community Development Block Grant was dedicated for point source remediation.  The first Youth Conservation Corps in Maine was founded to address water quality issues of China Lake.  Many programs have involved the local communities in making improvements to the watershed to help prevent harmful runoff from entering the lake. Though the water quality has not been restored to pre-1980 levels, the actions taken by the community have stabilized the water quality.

With these active and responsible organizations in place to deal with the water quality issues, considerable time and effort have been spent assisting lakefront and watershed landowners to implement non-point source best management practices to control soil erosion. In the Summer 2009 China Lake Association Newsletter, president Dave Landry wrote: "Since the China Lake Restoration Project was started in 1990, over 300 erosion control type projects have been done in the watershed of China Lake, all aimed at improving water quality."

Landry notes that the water quality has improved over the last 15 years but more work needs to be done to control erosion and create vegetated buffer strips. "The primary mission of the China Lakes Association is ‘to preserve and protect the water quality of China Lake,' so it is great news when we can report that last year China Lake had the best water quality that we have seen in 15 years! . . . One year of great water quality does not signal victory in the battle over seasonal algae blooms, but it is encouraging."

Keoka Lake Association, PO Box 97 Waterford, ME  04088