Minnesota watershed district talks tile intakes

WORTHINGTON, Minn. -- The Okabena-Ocheda Watershed District is working on several projects over the coming months and years in hopes of improving water quality in its trio of lakes, and it may be adding another project to their list.

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This rock inlet was installed by the Heron Lake Watershed District in a farmer's field. The rock inlets help filter out nutrients and sediment before the water reaches the underground tile. They also make it easier for farmers operating large equipment. (Special to the Daily Globe)

WORTHINGTON, Minn. - The Okabena-Ocheda Watershed District is working on several projects over the coming months and years in hopes of improving water quality in its trio of lakes, and it may be adding another project to their list.

During a meeting of the board of managers Tuesday, chairman Les Johnson raised concerns over surface tile intakes. Many farmers have them in their fields but the intakes are also prevalent in road ditches, carrying water away from land and into nearby streams and ultimately into our lakes.

Last fall, the watershed district discussed no longer permitting open tile intakes in farm fields, encouraging farmers instead to install more environmentally friendly rock inlets. While the district has no written policy on surface intakes, OOWD Administrator Dan Livdahl said permits for surface tile are denied unless they are part of a conservation practice built to specifications by the Natural Resources Conservation Service.

Instead, the OOWD encourages alternative tile (rock) inlets and provides a $300 cost-share to farmers within the district to replace existing surface tile intakes with them. The alternative inlets have been around for more than 20 years, but are gaining interest as farm equipment gets larger - and as it becomes more difficult to maneuver around the surface tile intakes typically marked by posts in farm fields.

The rock inlets allow for equipment to drive over them, and they are easier and cheaper to maintain. They work by installing a 15-foot-long perforated tile about 3- to 4-feet-deep, connecting with a tile line. Pea rock, or rock of one-quarter-inch to seven-eighths-inch in diameter, is placed around the perforated tile and acts as a filter, removing sediment and phosphorus from the water before it reaches the tile line.


According to a study completed by the Heron Lake Watershed District, one alternative rock inlet can reduce sediment loading by 400 pounds per year and phosphorus loading by one-half-pound per year. Livdahl said those numbers could vary depending on drainage characteristics and soil type.

Johnson said there are several surface tile intakes in his neighborhood, and with visible signs of soil erosion around them, he fears a lot of that soil and the nutrients it carries is ending up in Lake Okabena just a couple of miles away.

“We’re allowing a direct pollution source,” Johnson told the board. He’d like to see all of the tile intakes in road ditches replaced with alternative rock inlets.

Paul Langseth, a member of the OOWD Advisory Board and also a township supervisor, said there’s been no push in townships to replace surface tile intakes.

“We could start the ball rolling,” Langseth said. “You could have some early adopters, some mid-range people and, 10 years from now, you might have townships that haven’t done anything.

“If there’s a push to switch those inlets, I think it will happen,” he added.

The issue of who would pay for the replacement of surface tile intakes with rock inlets. The ditches are managed by townships, but owned by the landowners.

“If you’re serious about addressing tile intakes in the road right-of-way, I think you’re going to have to offer to pay 100 percent of the costs,” Livdahl said, noting that if multiple alternative inlets were constructed at one time, there could be a cost savings.


Manager Jay Milbrandt asked if the watershed district could identify some strategic areas where the surface intakes could be replaced with rock inlets.

“We’re doing so much on the west side and the north side … it seems like those are the natural places to start,” Milbrandt said. “I can see a lot of reason for us to fund the complete project.”

Johnson said the city of Worthington and perhaps the Lake Okabena Improvement Association would be willing to contribute to the project as well.

“How can we ignore a non-disputable direct pollution source?” Johnson asked. “Is there a worse source of pollution than to have a direct tile carry (surface water) right into the lake?”

Manager Rolf Mahlberg, while saying he supported switching out the surface intakes, also offered concern about utilities located within the road ditch rights of way.

“My electric, my phone, my rural water (lines are in the right of way),” Mahlberg said. “These rock inlets require space. Just be cognizant - my ditches are full of lines.”

Livdahl said he would look into the drainage issues further, and the board can further discuss ideas at its April 4 meeting.

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