Welcome back the sago pondweed to Storm Lake

Sago pondweed on the north shore of Storm Lake.


A sign of a healthier ecosystem, and no cause for alarm

The loon liked it



Weeds are finally returning to Storm Lake, and that’s a good thing.

Increasing water clarity is supporting a growing stand of sago pondweed just off the north shore between Scout Park and Methodist Manor. “That’s an indication that things are healthy. It’s pretty neat to see,” said Iowa Department of Natural Resources Fisheries Biologist Ben Wallace of Lake View, who oversees Storm Lake.

I have noticed it develop over about the past five years on dog walks along the lakeshore. It was just a little sprig off Lighthouse Drive a few years ago, but has spread into a substantial patch surrounding the Scout Park canoe launch.

Wallace attributes it to water clarity — plants cannot grow without sunlight — brought about by lake restoration. He adds that pondweeds like sago are important habitat for all sorts of aquatic life. Smart anglers know it is a spawning bed for yellow perch — one of the best-eating fish in the world that used to be thick in Storm Lake.

Also, the plant is rooted in a tuber and produces seeds that are especially popular with diving ducks and other water birds. The sago pondweed can provide up to half a duck’s diet during the warm months. Which explains to me why we witnessed a loon — the Minnesota state bird — taking up right in that spot near Methodist Manor for at least a week. At first glance I thought it was a mudhen, but what a delight.

Aquatic biologists consider sago an extremely important part of a healthy lake ecosystem. It is common and native to Iowa lakes that have some clarity. It holds soil in place, consumes nitrate and phosphorous to tamp down unhealthy blue-green algae blooms, and has become a bed teeming with life.

With water clarity at 36 inches commonly this summer, or better, the sago pondweed finally had the right conditions to flourish.

No doubt, people might become concerned about it, but they should check their alarm.

This plant can expand. It also can be easily controlled by IDNR. While it is true that Black Hawk Lake was overwhelmed by vegetation after rough fish were removed, it is important not to confuse Black Hawk with Storm Lake. They are very different. Black Hawk has more protection from the wind and is narrower. Storm Lake is a big bowl with a constant wind that promotes turbidity, even after dredging. The clarity we have seen consistently this year, safe to say, has never been seen in my lifetime. Now, clarity is ebbing as turbidity increases in the later summer. That annual cycle should hold most vegetation in check.

To be clear: Sago pondweed is not an invasive species. It is a beneficial species.

IDNR has been careful to listen to boaters who are concerned that water clarity could choke recreational activity. It cancelled plans to chemically clarify the water after boaters revealed their fears of a tangled green mess. Weeds have not been and will not be a problem at our boat launches or along the sandier southwest shore. We are most likely to see emergent growth around Scout Park because it has always been a silt collector and around Chautauqua Bay. According to everything I read, sago can be easily controlled by mechanical (mowing, which IDNR does at Black Hawk) and chemical means.

Diving ducks, rough fish and catfish also can uproot it. Sago has not had an easy time establishing itself here for many reasons.

Sunday, the patch was bubbling everywhere. The water around the patch was pretty clear but it was cloudy within. That tells me that all sorts of little critters are flitting around in there. Wallace said it is a refuge for zoo plankton that are the foundation of the aquatic food chain. If you pull up a plant it is likely to be lined by snails and small aquatic life. Big bubbles from one spot indicated to me that a turtle was down there, or that loon has a bigger set of lungs than Aretha Franklin.

For all the complaining that people do about Black Hawk Lake, fishermen will tell you that walleye angling improved there after rough fish were removed. The walleyes caught there are fatter than the ones caught in Storm Lake. They have a better feed source. I also have heard my friends tell about catching perch this spring, good perch. They go in cycles, but everything appears to be telling me that Storm Lake is coming back to life because of 20 years of dedicated effort by the city, the county, the state and the Lake Preservation Association.

Storm Lake has been devoid of vegetation and as such hasn’t had much for crappies and perch in years. Walleyes have not been able to reproduce in Storm Lake because it its turbidity. Maybe all that can change with smart management.

For now, let’s look at that patch of weeds as a victory. If or when it becomes a problem the IDNR will deal with it. In the meantime, may you find many perch this fall. And fat crappies too.