Tending to impaired waters

Talk about it

WORTHINGTON — One week after people gathered in Worthington to discuss the health of Lake Okabena, landowners and residents who live along the shores of Lake Ocheda met Thursday night to develop a consensus on how to best improve water clarity and water quality in the shallow prairie lake.

Organized by landowner Paul Langseth, the meeting included an overview of recent testing performed on Lake Ocheda, as well as a breakout session to give participants an opportunity to share their opinions.

“I’m concerned about the quality of the lake,” Langseth told the nearly 30 people in attendance. With the lake slated to join the Minnesota Pollution Control Agency’s impaired waters list this year, he said he wanted to be proactive in the approach to clear up the lake.

Nearly half of the meeting was set aside for Okabena-Ocheda Watershed District Administrator Dan Livdahl to give a report on the lake’s health. Livdahl, along with members of the Ocheda Beavers 4-H Club, completed a water sampling project on Lake Ocheda in 2008. Two years worth of samples were analyzed and the data submitted to the MPCA, ultimately contributing to the lake’s inclusion on the impaired waters list.

“(Lake Ocheda) is not alone by any means,” said Livdahl, adding that Lake Okabena is also expected to join the list this year. The channel that extends from Lake Okabena to Lake Ocheda has been on the impaired waters list since 2002. In each of the cases, the waters contain high nutrients and high levels of algae.

Livdahl said transparency tests performed on Lake Ocheda showed an average clarity depth of 8.27 inches. That compares to the 30-inch guideline the MPCA has set.

In terms of phosphorus, the nutrient that fuels algae growth in a lake, Livdahl said measurements averaged 227 parts per billion (ppb). MPCA wants that measurement lowered to 90 ppb.

Most of the phosphorus is tied to sediment particles suspended in the water, said Livdahl. Bottom-dwelling rough fish, such as carp, stir up the sediment particles and, because Lake Ocheda is such a shallow lake with a large surface area, the particles never seem to settle.

With an overload of phosphorus in the lake, algae will grow. Livdahl said samples tested for chlorophyll-a, an indication of algae growth, averaged 133 ppb — more than four times the standard level set by the state.

Call for action

The MPCA is expected to fund or conduct a study on Lake Ocheda sometime between 2011 and 2017. Livdahl said it will likely be done as part of a larger study on lakes and streams in southwest Minnesota that drain to the Missouri River.

“The thing about that is you can get lost and not get your individual needs met,” he added. “It would actually be better for us, if we can get the money, to get in earlier in the process.”

Access to funds would allow landowners in the watershed to implement programs that can help reduce the amount of sediment that gets into the lake. Agricultural Best Management Practices (BMPs) range from installation of terraces, grass waterways and filter strips, to implementation of conservation tillage and manure management practices. Replacement of septic systems, wetland restorations and water retention structures could also be funded.

Livdahl said BMPs can also be implemented in communities, and Worthington has already done work in the areas of storm water retention ponds, rain gardens, construction site erosion control, landowner education and regular street sweeping.

“All those things in the watershed will do some good,” said Livdahl. “I believe, and I think most people believe, that we also need to do some things in the lake basins themselves.”

Quest for clarity

“Everybody wants clear water in their lake,” said Livdahl. “In a shallow lake, it comes as a result of aquatic plants being in the bottom of the lake.”

In Lake Ocheda, there isn’t enough light penetrating the water to aid in plant growth.

Livdahl said if the lake could be drawn down for a period of time, and if the population of rough fish could be greatly reduced, it would help to establish aquatic plants. The plants would help stabilize the bottom sediments and, at the same time, provide good habitat for game fish.

At this time, Lake Ocheda has “pretty good populations” of northern and perch, although Livdahl said the populations are due to restocking, not reproduction.

“There really isn’t a lot of habitat for reproduction to be going on,” he added. “Unless you do something to change the environment, it’s going to stay like that.”

As for reducing the rough fish population, Livdahl said a chemical like Rotenone could be used. However with the waters from Lake Ocheda flowing into Lake Bella and the well fields that supply water to the city of Worthington, it isn’t likely that a chemical process would be approved. In addition to a temporary lake draw-down, other options include seining and controlling rough fish populations by stocking predator fish.

“My belief is that all of these would need to be used except Rotenone to control the carp,” Livdahl said.

A temporary lake draw-down would require approval from at least 75 percent of the landowners on Lake Ocheda.

The idea of dredging was raised during the meeting, although it would be an unlikely step.

“If you had all the money in the world and you could dredge Lake Ocheda, you’d still have water quality issues,” said Livdahl.

Coming to consensus

After attendees participated in small group discussions on the west, middle and east basins of Lake Ocheda, one commonality they all expressed was a desire to see a reduction in the rough fish and an increase in the game fish populations in the lake.

Those living on the east basin said they’d also like to see improved water clarity, a reduction in shoreline erosion and an increase in reed beds. On the west basin, residents would like to see a better functioning lake — one more useable for recreation and deeper than what it is now.

A couple of attendees questioned the methods the MPCA uses to improve lakes in the state.

Dave Vander Kooi, owner of Ocheda Dairy, said that because of the size of his dairy operation, he is required to have a CAFO (Concentrated Animal Feedlot Operation) permit and be regulated by the state for manure application. Other, smaller feedlots, however, continue to go unregulated, he said.

“At some point, they need to realize if they are going to make regulations for some, they need to make regulations for all,” Vander Kooi said. “There are some small feedlots that are causing problems in the lake.”

“As far as I’m concerned, if you want to do something, start by getting rid of the MPCA,” added Henry Pfeil. “Lake Ocheda is Lake Ocheda and you’re not going to do any good to change it.”

Rolf Mahlberg, who serves on the OOWD board, said it was important for the landowners to gather and learn more about the condition of the lake.

“We want public input,” he said. “If we came as a board with a plan and threw it at you, then you’d be mad that we never asked you.”

While no decision was made Thursday on the idea of forming a lake association, those present said they would like to gather again this summer, perhaps in a tour of the three basins.

Tags: lake ocheda, water quality, impaired waters, news, worthington, water