'Giant peninsula' in lake shows effects of drainage, but tile can be helpful, too
Administrator for Soil and Water Conservation District in Minnesota's Grant County says farmers need to think about entire watershed.
Jared House says he understands that field drainage is going to happen, but he wants landowners to keep the big picture in mind of how a project might affect a watershed.
“Some soil health practices work better on a properly drained field,” said House, the administrative manager for the Grant County Soil and Water Conservation District.
For example, improving water infiltration into the soil can prevent surface runoff that can lead to phosphorus, nitrogen and sediment washing into streams.
But drainage systems also can contribute to higher stream flows and have effects downstream.
“Everything we do in a watershed influences things downstream in that watershed,” House said, whether that is mowing a lawn, tilling a field or paving a parking lot.
House was sharing his observations at the Soil Management Summit in Waite Park in December, using a stream tray to model the effects of how water can move sediment and erode soils.
As a real-world example, House points to Lake Wilson in Grant County in west-central Minnesota, where House works.
He said satellite imagery shows that in 1991, it was a 30 to 50 acre lake on the Chippewa River that was 4 to 5 feet deep and a spot where locals might catch sunfish.
“Now it has a giant peninsula coming out of the middle of it essentially from 30 years of the river changing and depositing those sediments into the lake,” House said. “And a lot of those sediments did come from inside the channel itself because you have more water; it's scouring out that river and then it goes to an open basin and just dumps it out.”
He also points to Lake Pepin, the wide area on the Mississippi River south of Red Wing, Minnesota, that needs dredging regularly.
House said the Soil and Water Conservation District can help farmers with managing drainage and their soil.
“Our office can come in and help you look at what you can do with your soil to help amend it so that effectively, you'll have higher infiltration rates or water penetrating that background and getting to your tile systems and then out to the river or stream wherever it needs to go,” House said.
Different tillage practices or cover crops might help.
But House would like to see a slowdown in water runoff.
“I still think we need to hold water on the land, that we need less water entering our streams and our rivers for the effects that we see all over,” House said.
The right tile system can help reduce peak flows after heavy rains to avoid “flashy systems.”
“I also think there needs to be a lot more research on it (tile drainage); there hasn't been a ton done on that subject,” House said. “And one of the other concerns I want people to at least be aware of is groundwater penetration; we know nothing about what pattern tiling is doing for our aquifers. And that's just one thing I want people to be cognizant of when we move forward with these types of systems.”