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Water Quality Reports - 2023

2023

Cross Lake’s water quality in 2023 was excellent! Although we had some ephemeral algal blooms along shorelines in the late fall, there was not a "lake-wide" bloom, as shown in the water clarity chart. Our water clarity average was 3.5 meters (~11.5 feet), deeper than our recent annual average of 2.7 meters (~9 feet). We take biweekly Secchi Disk Transparency (SDT) readings at Station 1 (the “deep hole” close to the public boat launch) biweekly.

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Phosphorus (P) is a plant nutrient that in excess from the watershed causes algal blooms. The total phosphorus (TP-C) average of the sample results in 2023 was 12 parts per billion (ppb), much less than our recent annual average of 17 ppb, and below our Watershed-Based Management Plan (WBMP) 10-year goal of 14 ppb average TP. TP-C is the total phosphorus in a “Core” sample collected to a maximum depth of 10 meters (~33 feet), sometimes less. TP-G is a “Grab” sample collected one meter off the bottom of the lake, which we collect in August and September only. The TP-G results are higher than the TP-C results due to phosphorus released from the sediment.

 

Algal blooms are more likely to occur when chlorophyll-a (Chl-a is the green pigment in plants, including algae) is above 8 ppb. The average in 2023 was 8 ppb; our WBMP 10-year goal is 4.7 ppb. 

 

It could be an anomaly, but we hope it’s a trend and is due to the great work the NRCS in Fort Kent is doing with the Cross Lake Watershed National Water Quality Initiative (NWQI) funding and our grant work. Many thanks go to Alex Zetterman, NRCS District Conservationist, and his staff! We need at least 10 years of data to establish a trend.

 

We also take dissolved oxygen (DO) and temperature (T) profiles at Station 1 biweekly with the water clarity readings and monitor Station 3 in the north end of the lake monthly.

 

The colorful DO Profiles chart shows that in the spring and fall when the lake is mixed, the DO remains high throughout the water column, but in the summer when the lake "stratifies" into different temperature layers, deeper than 5 meters or so the DO goes below 5 parts per million (ppm) (called "hypoxia"), which is stressful to coldwater fish (salmon & trout), and is depleted to less than 2 ppm ("anoxia") at deeper levels, where coldwater fish cannot survive. That's why summer fishing for trout and salmon is generally not good in Cross Lake, although white and yellow perch and other “warmwater fish” do fine.

2023 Station 1 TP & Chl-a Results.jpg
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Learn more about Cross Lake

Explore more data and reports for Cross Lake here at Lake Stewards of Maine. Cross Lake's Midas number is #1674.

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