Luna Lake Issues To Finally Be Addressed

Luna Lake [Forest Service photo]

Chronic and long-term water-quality issues at Luna Lake near Alpine are finally being addressed by the Arizona Game and Fish Department. The Department is collaborating with the White Mountain Lakes Foundation and the Apache-Sitgreaves National Forest to install the first aeration system at Luna Lake during the spring of 2019.

Eventually other lakes located on the national forest: Carnero Lake, Lee Valley Lake and Crescent Lake could receive aeration systems.

If the concept and approach prove successful at Luna, funding for installation of aerators at the other three lakes will be pursued.

“Once started, installation of the aeration system at Luna should be finished in only a few months,” said Dave Weedman, Arizona Game and Fish Department (AZGFD) Aquatic Habitat Program Manager. “Luna Lake is the most cost-effective option because it is more easily accessible during the winter for maintenance than the other three lakes, and we have numerous partners in the area that will assist in the maintenance and upkeep of the facility.”

AZGFD biologists are monitoring water quality at all four lakes in an attempt to identify the causes for the water quality problems. Each of these lakes has periodically suffered from winter or summer fish die-offs as a result of poor water quality, low dissolved oxygen (DO) in the winter or excessively high pH in the summer. AZGFD has already solicited plans for installation of aerators to address low oxygen during the winters, and is pursuing the needed environmental clearances to pave the way for installation and operation of the equipment.

According to the Department, each of these lakes is different and will require a multi-faceted approach to address the water quality causes for the fish die-offs:

Crescent Lake receives an elevated level of nutrients from the watershed that contributes to excessive plant and algae growth. During the winter, as the lake ices over, transfer of oxygen from the air to the water is cut off, as is production of oxygen through photosynthesis by the plants and algae, while decomposing plant matter under the ice burns up all the oxygen, leaving none to keep fish alive. Aeration, in combination with nutrient control, may prove to resolve this issue.

Luna Lake suffers from a similar condition during the winter, as well as an elevated pH and low oxygen problem during the summer as excessive plant growth and blue-green algae absorb carbon dioxide, causing the pH to rise during the day. At night, when photosynthesis shuts down, the production of oxygen also shuts down. Respiration by zooplankton and decomposition by bacteria consume oxygen, causing a daily low DO condition that may stress and/or kill fish.