Yes, Como Lake stinks. But that’s not unusual for this time of year, the Capitol Region Watershed District says. The short explanation: Blame the odors on a combination of more sun, hotter temperatures, aquatic plants dying, algae growing, and heavy rains that wash nutrients from our yards into the lake, says project manager Britta Belden.
It’s a vicious cycle, she says. Summer weather itself promotes the growth of algae. Summer weather also promotes the decomposition of curly-leaf pondweed — a nasty invasive that out-competes native plants, alters the lake’s overall ecosystem, then dies out naturally at the end of June. As dead curly-leaf pondweed decomposes, it promotes the release of more phosphorus, which feeds more algae growth. Decomposition also reduces oxygen levels and releases odoriferous gases such as methane and hydrogen sulfide. That’s what we smell. Making things worse: this year’s excessive rains, which create more storm water runoff, which adds more phosphorus to the lake, which feeds the cycle.
The water quality of the lake — though “very compromised” overall — currently is about what’s normal by historical Como standards, Belden says. Recently collected water quality readings are consistent with the lake’s historical July data. In fact, while phosphorus concentrations currently are very high, bacteria readings actually are very low, she says.
See how the watershed district is trying solve this problem long-term by targeting curly-leaf pondweed and other steps.