Spring is in the air… let’s hope fertilizing is not! Lake Cavanaugh’s water quality is at risk every time someone fertilizes their lawn, or uses phosphate soaps or detergents in their house, on their roof or surrounding property. Typically, algae growth is limited by the amount of available phosphorus in lakes. So even if there is excess nitrogen, it will keep things in check if phosphorus remains low. But phosphorus builds up in the lakes over time. It gets used by plants, then when they die and decompose, the phosphorus returns to the water. It doesn’t go away. So if people are pouring more and more phosphorus in the lake by fertilizing lawns, it causes persistent algae blooms and eventual lake “extinction” events that require chemical treatment interventions.
The monthly water quality testing at Cavanaugh now includes monitoring for phosphates and nitrogen. Spikes in phosphate levels are being seen at beaches where green lawns are present. These phosphate level spikes are approaching the high-risk zone for algae blooms (0.07 ppm). One alternative to consider, is planting micro clover (Trifolium repens var. ‘Pirouette’) instead of grass. It stays green naturally, never needs fertilizer, and requires less mowing. We all need to be vigilant about not using phosphates around the lake. Please consider attending the next LCIA meeting on May 24th to hear more about the water quality program and results. Thank you for helping keep Lake Cavanaugh clean!