Water levels continue to decline at Lake Fisher, one of the City of Concord’s raw water supplies, causing some areas to continue experiencing reduced water clarity. The City of Concord Water Resources Department is working to remove the discolored water as quickly as possible from the system. Despite the unappealing aesthetic, the water continues to be safe for normal use and consumption and residents do not need to boil their water.
Water levels at Lake Fisher have reached extremely low levels. The lake is currently about 7.5 feet below normal water level. As water levels naturally dropped, it caused an excess amount of air to be drawn into the city’s water intake structure. This caused increased turbidity, or cloudiness, in the finished water supply. Turbidity is a measure of water’s relative clarity.
The Water Resources Department adjusted the city’s water intake to correspond with declining water levels at Lake Fisher. Specifically, there are several intake valves which enable the department to adjust to natural fluctuations in the lake’s water levels. The city is able to close valves that are above the water line and open valves at appropriate levels below the new water level.
As the lake levels drop, the city’s water intake structure pulls water that is closer to the bottom of the lake. On the bottom of the lake is sediment that has collected over many years. This sediment has concentrated levels of manganese, a naturally occurring mineral found in rocks and soil. Manganese is also found in many foods we eat and our bodies need some manganese to stay healthy.
Although not required, the city tests its water supply for manganese every day, 365 days a year, and removes it through the water treatment and filtration process. During normal conditions where the lake is full, the concentration of manganese is less. However, with higher concentrations resulting from current low water levels, the city’s ability to remove all of the manganese from the finished water is adversely impacted, causing the discolored water that many customers are experiencing. The department will continue to adjust treatment processes to maximize removal efficiency.
The Water Resources Department worked to flush as much of the discolored water from the system as possible. The continued decline in Lake Fisher’s water levels, however, requires additional actions to expeditiously improve the clarity of the city’s finished water. The city has begun pulling additional water from Lake Howell and Albemarle to relieve pressure on Lake Fisher and allow time for water levels to naturally improve. Initiating this change in the system requires the water to change directions within the network of pipes. This change of water direction may result in continued water discoloration for a short time.
The Water Resources Department is continuously analyzing the water to ensure its safety; all water quality measures continue to be met. While the discolored water is visually unpleasant, it remains safe for normal use and consumption.
Low water levels at Lake Fisher Intake Structure
Low Water Levels at Lake Fisher Boat Ramp & Intake Structure