What you need to know about this fall's historic drought

[MUSIC PLAYING] CATHY WURZER: In our top story, the majority of Minnesota communities are experiencing abnormally dry or drought conditions. According to the state DNR, two sections of Southern Minnesota are in extreme drought, including southwest Lyon and Redwood counties. And to the southeast, Hennepin, Carver, Sibley, and Scott counties.

Late fall is a critical time to get moisture into the ground. Here to talk about the situation is Pete Boulay. He's the assistant state climatologist with the State Department of Natural Resources. Hey, Pete. How are you?

PETE BOULAY: Doing fine, Cathy.

CATHY WURZER: Good. Glad you're here. Thank you. Well, as I just mentioned, we're heading into a critical time. We've got to get water in the ground. But explain why is late fall so critical?

PETE BOULAY: Well, this is about the time of year when farmers are out in the fields early in the fall. You still have a crop, the surface of the of the ground is sealed, so water can't penetrate to it. And we also have more intense rains early in the fall.

When you get in the late fall, which we're now getting into now, the fields have been tilled, there's no crop, less intense rain. So about 70% of what falls right now will be stored in the ground. So this is a very critical period, between now and when the soils begin to freeze.

CATHY WURZER: So I know we're in a deficit. How dry is the soil right now?

PETE BOULAY: Well, it's looking pretty bad. There's one place in the state that still measures soil moisture by weighing the soil. They take a column of soil going down into the ground, they weigh it, see how much water is missing. And that's at Lamberton at the Southwest Research & Outreach Center.

And on October 15th, there's about three inches short of normal. And basically, there's no moisture left at all in the top two feet of the profile. And that's about the same here in the Twin Cities too.

CATHY WURZER: Wow. So if we don't get the moisture that we need, which is we need several inches obviously, what happens next year?

PETE BOULAY: Well, I think the drought will probably get worse before it gets better. And then once we freeze the soils, we get locked in a bit. The big wild card, of course, is what happens in the winter too. It could range from only 5% of the moisture going the ground to 50% of the moisture.

If the soils don't freeze and we get a heavy, early snowfall, then it can percolate into the soil over the winter. So that's another thing that could happen too. But in general, it would be very difficult to totally lift Southern Minnesota out of the drought by the time spring comes at this point. We just need too much moisture to really erase that deficit.

CATHY WURZER: And just to be clear, are we talking what, eight, nine, 10 inches?

PETE BOULAY: Well, anything will help at this point. I'll take any precipitation, solid or liquid. In the Twin Cities, we're about 10 inches short since June 1st. Now, we wouldn't need all 10 inches to really help things out. The first thing that would happen, we have to saturate the soil. The more precipitation we get, then it would begin to run off into streams and help refill the lakes.

CATHY WURZER: I'm wondering here, should we be worried about consecutive drought years versus one dry year?

PETE BOULAY: Oh, absolutely. If you look at-- a good barometer of drought is looking at Lake Minnetonka water levels over time. And the multi-year droughts really stand out. The last one we had that lasted more than a year was the ADA drought, which Lake Minnetonka didn't really recover until 1991. So right now, Lake Minnetonka right now, today, is at its lowest level since 1991. So the big if is, do the rains return this fall into winter? And if not, we'll be starting out in a deficit when the ice comes off in the spring.

CATHY WURZER: A lot of people, of course, are talking about Minnehaha Falls dried up, the creek that leads to the falls just a few puddles. And gosh, it's a concern for many people. But this is not the first time that's happened?

PETE BOULAY: No, we've seen that a few times in the past. We've had these mini-droughts. 2009 is one. There was one in 2000. Any time we have a multi-month deficit of precipitation, they close the dam in Grace Bay. If there's anything left in the stream, it begins to dry up.

So this has happened before. I wouldn't be too concerned about it. I think Minnehaha Creek will return eventually. We'll just need some pretty good rains for it to look anything spectacular or photogenic.

CATHY WURZER: Lake Minnetonka is low. And I wonder, is it starting to affect ground water levels?

PETE BOULAY: We've seen some lower ground waters in the-- ground water levels in the state, compared to a year ago. It's really hit or miss. Some are still OK. One thing that's interesting about this drought, compared to last one, is that the Mississippi in Minnesota at least isn't really that low. We had such a wet spring, especially up in the headwaters and also the Minnesota River too. It's still not too bad.

Now, smaller streams is a total different story. Smaller streams are very low like the Sock River in St. Cloud, some streams in southern Metro. Here and there, they're very low. But the main ones aren't. So it's a mosaic of some places, including groundwater is still OK. Other places are low.

CATHY WURZER: What do you think of-- and I was just pondering this the other day. Last year, the drought was up north. Now, it's right across the Twin Cities and point south. Is that an odd pattern to have?

PETE BOULAY: Well, it's a big state. Any droughts we've had in the past has been like this where some places are just closer to the storm track. Northern Minnesota really stayed fairly wet most of the spring, especially the spring and into the summer. And right now, Northeast Minnesota, Northwest Minnesota, there's no drought at all.

Here in Southern Minnesota, we really never got in that good zone of storm track. We never really had those big storm complexes that usually happen in the middle of the night across Southern Minnesota. They never really happened this summer. So that was missing from the equation.

It all adds up month-over-month. Ever since June, every month has been a deficit basically in east central Minnesota, southwest Minnesota. So it's adding up one month at a time. And as soon as-- what we need is the storm track to change and has to be in direct line of these storms.

CATHY WURZER: It looks like the storm track is going to change-- well, I shouldn't say change fully here, but it looks like we're going to get some moisture this weekend, at least Sunday into Monday.

PETE BOULAY: Yeah. And we only need about another five or six or seven of those, and then that would help.

CATHY WURZER: But we're looking at what, one to two inches of water possibly?

PETE BOULAY: If we're lucky, it would be nice that I've been-- we keep track of these two on the models. And of course, Paul Huttner will probably have more to say about it than I would. But definitely anything like that is, we're optimistic that hopefully things will change and we'll get something. It'd be nice to have a large system to cover a good chunk of the state and maybe favor southern, central Minnesota.

CATHY WURZER: Yeah, we'll see what happens. Pete, thanks for taking the time to talk with us.

PETE BOULAY: Great to be here.

CATHY WURZER: Pete Boulay is the assistant state climatologist with the DNR. Now, a listener in Roseville wrote in with concerns about urban trees being stressed because of the drought, which is a really good point. So we wanted to bring in another expert. Ralph Sievert is the director of forestry for the Minneapolis Park & Recreation Board. And he's on the line right now. Hey, Ralph, welcome.

RALPH SIEVERT: Hello. Good to be here.

CATHY WURZER: Hello. Thank you. Well, you just heard here and, of course, you'd know, you've been on the ground, that the Metro area has been in a pretty serious drought for months now. What's happening with the trees in the area?

RALPH SIEVERT: Well, as was mentioned, we've got a combination of one year followed by another year where it's so dry. That does take a toll. And so the newer trees, especially when they're still establishing a new root system, it's harder for them to do that.

But also, the mature trees. People have trees in their yards, and a lot of times they think, well, that tree is established. It's been there. Even the dryness can affect that big tree and even, in some cases, make it more susceptible to what we call secondary pests that take advantage of a tree that's stressed, especially with lack of water.

CATHY WURZER: Now, in the next few weeks, until the ground freezes, how often should folks water their trees and shrubs?

RALPH SIEVERT: Well, we always recommend at least once a week. More than that is more beneficial, but at least once a week. And if you've got a larger tree, you almost want to make sure you're saturating what we call the out to the drip line. In other words, as far out as the branches go.

Because those roots are out there into the soil. And roots grow like a pancake. They don't grow super deep. They're really in that top to feed. So the more you can saturate that area under the drip line of the tree, that's the best thing.

Smaller trees, you can almost do by letting a hose trickle, especially the ones that were just planted this spring. But those bigger trees, really a sprinkler is the better way, or a soaker hose is the better way to go.

CATHY WURZER: I was going to ask, how do you water such a large tree if you've got a big tree around the drip line? Just go almost in a clock like noon, just go around in a circle? Is that the best way to do it?

RALPH SIEVERT: Yeah. As long as you just periodically go-- like once an hour. You could move that sprinkler around every hour to really saturate. Now, if we do get some rain this weekend, that helps. But it's not going to hurt to do more in advance.

I know that this weekend, knowing the weather is going to be halfway decent, I've got some big trees in my yard, and I plan on putting that sprinkler out there. And sometimes, people look and think that's odd because they don't think things are growing. But you're really getting things ready for the spring by really getting that moisture into the tree now. Because we're not fully dormant. The trees that still have leaves, they're still bringing up moisture from the soil.

CATHY WURZER: Before you go here, Ralph, could you tell us what you think the state of the trees are in Minneapolis? How would you describe their overall health?

RALPH SIEVERT: Overall health is good. It just depends on how long we keep seeing repeated droughts in subsequent years. Because in 2019 and 2020, we actually had a decent amount of rain when it comes to trees. Last year and this year is a different story.

So like in our case, we planted 9,000 plus trees the last two years. So we've had crews working overtime the last two summers just to get water on those trees and get them through the summer.

But this is still a crucial time, this time of year, to make sure we keep them hydrated so when the spring comes-- and it's similar to what was just being described in terms of the farmer's crops, in terms of the soil being ready. And then when spring comes, they've got that moisture that has already hydrated the tree.

The other thing too are conifers, the evergreens. Those are the trees that you don't think about it, but they've got green needles all winter long. And so they are actually losing moisture in the winter when there's winds and that, sort of, thing.

So in some cases, you can see conifers or the evergreens even desecrating or looking-- turning out to be brown in the spring because they just didn't have the moisture in their system to get them through the wintertime.

CATHY WURZER: And I'm bet-- I'm betting if they come through the winter dry, that leaves them in a deficit and that they could be susceptible to bugs and that, kind of, thing?

RALPH SIEVERT: Right. And probably the most notable one for oak trees, especially the bigger burr oaks is called two-lined chestnut borer. It's an insect that takes advantage of a big oak tree that's been stressed from not having enough moisture. And so we're seeing some of the those symptoms now.

CATHY WURZER: All right. Thank you so much for your time here. We appreciate it, Ralph. Thank you.

RALPH SIEVERT: You're very welcome.

CATHY WURZER: Ralph Sievert is the director of forestry for the Minneapolis Park & Rec Board.