WATER QUALITY MONITORING

There are many imminent threats to Maine lakes. Near the top of the list, and perhaps the most pervasive, is the potential for lakes to become nutrient enriched and more biologically productive as a result of development in lake watersheds. This condition is characterized by declining water clarity (transparency), resulting from an increase in the growth of algae. Excess algae in lake water can cause a disturbance to the normal equilibrium of the aquatic ecosystem. As algae die and decompose, bacteria consume oxygen that is dissolved in the water. Increased algal growth can lead to a decline in oxygen levels, especially during the warm summer months. Oxygen loss can reduce critical habitat for coldwater fish (trout and salmon), and it can accelerate the decline of water quality.

The enrichment of lakes with the nutrient phosphorus and excess algae, resulting from watershed development, is referred to as “cultural eutrophication” (CE). Stormwater runoff from disturbed or developed areas of lake watersheds typically carry high concentrations of phosphorus, sediment particles, and other pollutants considerable distances, eventually flowing into a lake. Lake watershed boundaries may be situated close to the shoreline, or they may extend for miles away from the lake. In either case, stormwater runoff from developed areas of lake watersheds is a potential threat to water quality, unless conservation practices are in place to control stormwater runoff.

WATER QUALITY RESOURCES

LAKE STEWARDS OF MAINE TRAINING & CERTIFICATION

The LSM trains and certifies volunteers to collect scientific water quality data of the highest quality. Each volunteer participates in an initial training workshop and is re-certified on a regular basis. Most volunteer lake monitors collect transparency (water clarity) data with a Secchi Disk and a viewing scope.

MEASURING LAKE CLARITY

The primary focus of volunteer water quality monitoring is the collection of information related to changes in lake biological productivity over time. Water quality data gathered by volunteers can be used to determine whether individual lakes are becoming more productive, less productive, or are stable. Many years of data are generally required to make these determinations with confidence.

KEOKA WATERSHED PROJECT

The Keoka Lake Watershed Project involved surveying, documenting and then fixing areas within the Keoka Lake Watershed that were eroding and causing a negative impact on Keoka’s water quality. During the survey portion, volunteers from the Keoka Lake Association and residents from within the watershed as well as staff from the Department of Environmental Protection, the Soil and Water Conservation District and LEA helped locate, map out and document 65 sites where erosion was occurring. This information was then compiled into the Keoka Lake survey report which functions as a landowner handbook and reference for future mitigation work.

KEOKA WATER QUALITY REPORTS

Long-term trend analysis indicates chlorophyll–a concentrations in Keoka Lake are stable, total phosphorus concentrations are decreasing, and clarity readings are increasing. The average color reading for 2020 was 19.00 SPU, indicating that water in Keoka Lake is moderately colored. Suitable cold water fish habitat was present through June. As water temperatures increased and deep water oxygen was consumed, cold water fish habitat became moderate in July and became unsuitable from August through September.

Keoka Lake's Water Quality Reports (PDFs):

2024 Algae Monitoring Summary,

2024 Mid-Season, 2024, 2022 Mid-Season, 2021, 2020, 2019, 2018, 2017, 2016, 2015, 2012, 2011, 2010, 2009, 2008, 2007