From Paul Robertson
Devils Lake Water Improvement District
The Harmful Algal Bloom that began around parts of the lake in mid January to early February in what is often our coldest times of the year morphed into not only a lakewide bloom, but most recently into one with colors and looks unfamiliar to most of us. The white, blue-gray, green, blue-green, oily, latex paint looking scums seen around the lake in the earlier part of the week have fortunately dissipated. However there exists a strong potential for scums to form again should the winds die down or if the blue-green algae are blown along the shorelines as the lake is an aqua-marine color and thus very much in a bloom, it is just mixed throughout the water column and thus toxins may be present.
Remember as Oregon Health Authority will say that anytime of the year, the best precaution for recreating on lakes is “If in doubt, stay out.”
Samples taken today are being processed for toxins and total blue-green algae concentrations. Data should be back by the end of next week.
In the meantime we can say this; the odd colors we have seen lately are consistent with Blue-Green Algae Blooms. As far back as 1994 the lake suffered a similar documented bloom as shown in the slideshow last night. One of the primary risks associated with Harmful Algal Blooms are toxins, so as mentioned we are working on getting updated information. Other primary issue is oxygen depletion as the bloom dies and decomposes. Testing today confirms this is an issue in Devils Lake.
The dissolved oxygen in the lake is between 35% and 65% of normal for the main lake. Low oxygen stresses and can kill fish and wildlife. Following a recent stocking of rainbow trout dozens of fish were found dead near where they had been stocked the day before at Regatta Grounds. Thousands of fish have been stocked over the last month or so, so thankfully we have not heard of any other fish kills. All other measurements, pH, conductivity, temperature, were within the normal range of the lake as shown below:
Dissolved Oxygen Saturation: 30% – 70% in water column
Dissolved Oxygen Concentration: 3.93 – 7.17 mg/L in water column
Lake Temperature: 12.4 C to 14.5C (54F to 58F) in water column
pH: 6.31 to 6.61 around the lake
Conductivity: 113 to 127 uS in water column
Lake Level: 9.70′ (Maximum summer time impoundment is 9.53′)
Look for future updates at the normal weekly interval and through our website next weeks as we get an early start to the monitoring season and get fully ramped up with all the water quality data including E.coli and others as we have done for the last several summers.