Posted on March 6, 2024
The winter, the Minnehaha Creek Watershed District (MCWD) planned to dredge the Nokomis ponds. These ponds are called constructed wetlands and sequester sand and debris. The vegetation growth also takes up phosphorus before the water travels into Lake Nokomis. These constructed wetlands need periodic maintenance which includes removing invasive species, removing and replacing vegetation that takes up phosphorus, and dredging accumulations of sediment to restore capacity.
Five years ago I asked MCWD personnel why the wetlands on the southwest corner of Lake Nokomis, which appeared to be expanding, had not been dredged. I was told that, due to high precipitation, the area was too wet for their equipment. So the maintenance was postponed. Since then, the MCWD has given the vegetation a haircut, which removes some phosphorus buildup. But now the dredging has been postponed again because the ground was not frozen enough for the equipment.
Like the Lake Nokomis ponds, we have two more bodies of water that are also in need of attention. They are Minnehaha Creek and Lake Hiawatha.
In 2022, due to the drought, I had an opportunity to inspect Minnehaha Creek where it runs through Hiawatha Golf Course. The creek bed was totally dry and it was full of sand. I dug down at least six inches and could not find the bottom of the creek bed. This showed that, much like the constructed wetlands, the capacity of the creek had become compromised. This reduces the ability of the creek to handle high flows of water. This is also true of the creek outbound from Lake Hiawatha. Also, the buildup in the outbound creek elevates the level of Lake Hiawatha, reducing the lake’s capacity for handling water during high precipitation events.
Then there is the water quality of Lake Hiawatha. It has effectively become a constructed wetland. It accepts sand, debris and pollution from Minnehaha Creek and outfalls which collect in the lakebed. But there is no maintenance, as is evidenced by the two islands of debris in the lake, one at the inlet and one at the 43rd Street pipe outfall. Lake Hiawatha used to be dredged periodically to remove this accumulation, thus cleaning the lake and restoring capacity. But this has not been done for many years.
It is time for the MCWD and the Minneapolis Park and Recreation Board to provide the same maintenance for Minnehaha Creek and Lake Hiawatha that they propose for the Nokomis ponds, which is to clean them and restore capacity.
