[00:00:00] Bridget Scanlon: Welcome to the Water Resources Podcast. I am Bridget Scanlan. In this podcast, we discuss water challenges with leading experts, and today I'm delighted to welcome Mike Dettinger, who is a senior research scientist at Scripps Institute of Oceanography in the Center for Western Weather and Water. We previously recorded a separate podcast on Atmospheric Rivers in November, 2022 and focused on droughts.
But since there's been so much activity in this space between November and Dec, or December and January in California, we thought it would be good to add some more material for that podcast. So, thanks Mike for joining me today. I really appreciate it. So, you've been following and tracking these atmospheric rivers in California since the holidays, and maybe you can describe what you were seeing over that time period.
[00:01:03] Mike Dettinger: Yeah, so as we talked about last time, California has been in a serious severe drought from the past three years, and in November we were kind of looking with some trepidation into the future and wondering whether anything, whether that was likely to change or whether pile another drought year on top of what had already been going on. And then in December, things turned around for us in a lot of big ways. At the early part of December, we continued to have conditions over the North Pacific that prevented storms from showing up in California. And specifically for our purposes, atmospheric rivers were just being held at bay by this high-pressure ridge that extended down from pretty much the Bering Strait offshore of California and was just acting as a barrier to storms reaching us. And then, I believe it was around the 18th of December of 2022, that ridge, that high pressure system started to break down. And ultimately by pretty much the holiday, by December 26th what we often say here is the door had opened and the first of a series of Atmospheric Rivers (ARs) arrived on the west coast in California, and for instance, at San Francisco, that first one, which kind of peaked it's landfall, on the 26thor the day after Christmas, arrived. And as I say, there was a whole sequence of them and we got, over the course of the next, let me say three weeks, so through the New Year's and for the first couple weeks of January, with a little bit of it, it gets hard at the end to figure out exactly where you've run out of them, because there were still some storm small storminess showing up and things like that.
But, anyway, we had nine of these things arrive. So with sort of some suitable, three day or four day gaps in the middle there, we basically had about two or three of these showing up a week for the next three weeks. And, they brought a lot of precipitation to us. And so we had a situation where the soils were dry.
There wasn't much snow anywhere to be found, and the reservoirs were low and the rivers were low for that matter. And at the beginning, at pretty much at Christmas and then, these storms started showing up, boom. One after another. and, let me see. My count was something like, yeah, my count was that we had three clusters of ARs. So like I say, you'd get two or three of 'em in a row and then there'd be a bit of a break, three or four days and then three or two or three more and so on. And, we had three of these clusters, which the term that we use now is families of ar. We had, let me see, so there was the one strong one in San Francisco? There was the one strong one at the beginning at December 26th And then we had three pretty minor ones, well, actually four pretty minor ones thereafter with, well, lemme think about that. Yeah. Three or a couple more, minor ones. And in between, sort of mixed in, there were some in between storms for this particular sequence.
When I talk about in between storms, basically I'm being very vague about this. Terminology for this. The terminology for this, is such that the first one, the big one that I keep mentioning, is in the realm that we consider to be most likely hazardous in and of itself, it's likely to cause issues.
The minor ones, we expect, and history tells us that, those are mostly beneficial storms. They wet the soils, they put some water in the streams, they put some snow on the mountains for the most part. It's not that nobody's inconvenienced, but for the most part they're just good news. We needed that. And then the in between one is kind of anyone's guess exactly how that's gonna play out. Those are the ones where we expect to see some winners and some losers, more so than the other extremes.
[00:05:46] Bridget Scanlon: and the classification that you're referring to, as beneficial or harmful or whatever.
Yeah. This is what Marty Ralph developed early on, or like a class, five different separate classes. yeah. With units of 250 each kilogram per meter per second.
[00:06:01] Mike Dettinger: Yeah. So actually the trick with the scale that Marty developed, is that what you know, his insight and I remember being at some meeting or other and sitting out in the meeting hall and talking with him about this when he started really saying: We need a scale because people don't know if you are increasingly failing to understand not all ARs are huge storms and flooding and all that stuff.
We need some way of actually categorizing and describing ARs so that people will get a better handle on both our fellow scientists and the news media, and the public will develop a better sense that, oh, there's an AR coming, but it's, don't panic. This is actually good news. Versus there's ARs are coming, man, you better look at your flood ditch and see whether or not you know it's, you want to clean it out because there's gonna be some water in it soon. That sort of thing. Trick or the innovation that Marty suggested was that rather than just say, oh, this AR is carrying a lot of water, the units you were talking about. The other thing that really matters is in addition to how much water it's carrying is how long it's gonna be sticking around and dumping water on you.
Some of the AR ARS will reach the west coast and sort of zip down them over the course of a day or two, and never in no single place did they ever get much time to really put a bunch of precipitation down, total precipitation and other, whereas other storms will reach the west coast. And for a variety of reasons, they will stall and they'll sit over you for, a day or two days or even, three days. We'll see sometimes and under those conditions, basically it multiplies. The amount of precipitation you get is the rate of precipitation, which an AR that's carrying a lot of moisture will drop water fast. But also how that rate of precipitation is coming down on you. And so we have this scheme that is where the AR one first category is the beneficial end of the spectrum. And those, they're either very weak in terms of not much specific, yeah, not much precipitation is following in the inches per minute or whatever you want to call it. But it doesn't, also, doesn't stick around that long and you can get a situation where it can stick around a while, but if it's really weak and yeah, just it's drizzling for a day, we can live with that At the other end of the spectrum, you can get a wider range of things and you can either get an AR that is just dumping water like crazy and those can do a lot of damage even in a short period of time. But other storms will be dropping precipitation, rain or snow at a pretty steady clip. But they also stick around for two or three days and they, that is, they end up being the equivalent or worse than that, than a storm that is fast but doesn't stick around. And so we have this grading scheme that takes both of those into account.
[00:09:35] Bridget Scanlon: Right. And so, from that record that you sent from San Francisco, it seems like the durations ranged from about,11 hours to 63 hours or something like that, based on their classification. And then, the intensity ranged all the way from like, 25, maybe over a thousand kilogram per meter per second. And, the first one was the most intense it looked like. That's right.
[00:09:57] Mike Dettinger: That's for San Francisco. One thing you need to understand is that these storms, they evolve the whole time and coming across the Pacific, but also as they move along or down the west coast, they evolve. And so actually if I moved down to LA during the same period, it was the last one, they got a grand total of call it five ARs in that same period that managed to get all the way down to Southern California, and it was the last one there that was actually the highest score, let's call it that. And that one was the highest score, was the most hazardous because it ended up sticking around for an extended period. by the the time it got down there. Right. It wasn't markedly more intense than the others that reached there. It just hung around long, but it just hung around more. And so, one of the complications of this whole business is that, these storms do evolve. And so I can make a wonderful statement about, oh, what, here's what happened at San Francisco. Somebody sitting down in Los Angeles will say, that's not how I remember it. So, right.
[00:11:17] Bridget Scanlon: So, I mean, these ARs then they would qualify as drought busters, based on, well,
[00:11:22] Mike Dettinger: That's a topic of, like some serious conversation. and the thing is, if you wanna look at the whole state of California, there's a good, I would say there's a good third, the central third of California looking from north to south is, the precipitation deficits that we had built up over the past three years. And the reservoirs, I don't have data in my hand, but I'm assuming the soils and vegetation got enormous relief. They were, that central part of California was, for the most part it was a bit over a year's worth of precipitation behind over the past three years.
This is one way I like to measure how deep the drought has gotten, so, it was a full year behind, over the past three years, and most of that central third of the state. Now, if you look over the past three years plus, our water year to date now, no longer has a deficit. It's slightly normal over the, over that period. And that really came from December, January, with a little bit of help from February. Just a small amount of help from February. And so, okay. The central part of the state, in a precipitation sense is kind of, I would say arguably, yeah, this broke the drought in terms. At least the major rivers in that area are flowing. But remember there were those big reservoirs, there were lots of reservoirs, for instance, in the Sierra Nevada that were pretty darn empty. And so it's not like we're seeing big floods or something coming out of those rivers.
For the most part, it's just that they're falling enough to have done really good things for our reservoirs. And indeed, right now, literally outside, it's been, I'm sitting here in Carson City, it's snowing a little bit and it's gonna snow a lot more in the next couple days. And on California side of things, people are really kind of jittery about whether or not, with all the snow that got laid down in Jan, December, January in the mountains, that this storm it's March, approaching the middle of March-ish. It's gonna be a warm storm, and so there'll be a lot of rain, more rain in it than in the storms that we're talking about earlier. And so we expect to see rain falling on snow and rain running off of the snow. And in the process probably melting, especially some of the lower altitude snows.
And so people are starting to get nervous about flooding and yeah, people are watching and worrying about the possibility of flooding. The reservoirs were low, but, storms that we went through in December, January, did in fact refill, in some cases just refilled the reservoirs and others.
They filled it up a lot more. And so now, if a bunch of water comes down, you have to start worrying about possible floods again, because the reservoirs won't necessarily be able to hold it, but that's the middle of the state. And the debate is that when people will say, oh, California's outta the drought.
These storms largely missed the very northern end of the state up around and north of the northern end of the Central Valley. If you know your California geography at all, they certainly really missed the desert part of the state, which is down in the southeast corner of the state, the Mojave Desert and the Colorado River Desert. And pretty much that didn't get anything. And so, when somebody says California's out of drought, I always cringe because it's like, eh, it depends on where you are.
[00:15:25] Bridget Scanlon: If you look at the US Drought Monitor and the time series for the state, Yeah. It almost stops overnight, yeah.
[00:15:31] Mike Dettinger: yeah. And that is, you mentioned drought busters and that kind of one of the realizations as we dove into this atmospheric river stuff is we really started looking at how droughts begin and end with an eye towards, okay, how do these big storms interact with droughts? We occasionally, and actually it's not rare, it's just occasionally we get floods in California, right in the middle of droughts.
We get a storm in that will put enough water down that will end up with having flood damages and things in sort of selected areas in a particular storm. And then, if that storm ends and fall back into the same patterns that gave us a drought before. We pretty much never really left the drought.
We just had a burst of water that ran through the system, flooded and was on its way. So floods and droughts are not, mutually exclusive in California. But one of the things you noticed when we started asking, let's all look at the floods. Look, let's look at the droughts and how they begin and what we found.
Was that historically we found something that actually applies across almost the entire US that was part of the surprise, but was that droughts begin, we go into droughts relatively slowly, but historically to a really great extent, droughts tend to end with the arrival of a wet month or two. In California, I was able to sort of chase it down to just looking at the wettest three days in a given month, in each month. And it comes down to, you can turn around of drought in a three day storm sequence in California. Some of these droughts like we were just in, that were really pretty severe. They were both warm and dry so that they really tended to dry out the soils and everything with a lot of evaporation going on. Those can take a bit more, but California sort of serves it up in see things like this December, January period we just went through where, like I say, nine of these big storms blew in and the combination of nine well, three or four of them were pretty good size storms. And of the nine, well, then just having nine of 'em. Even those beneficial storms, they basically set the stage so that when a big storm blows in, you don't get any benefit of the water sinking into the ground or that sort of thing. The ground's already wet because you had some of these beneficial storms and so, these sequences of storms are really, they certainly do a good number on ending these droughts, busting these droughts.
We went through this, yeah, a few years ago. Yeah, we had a right four year drought, 2012 to 2015. 16, and 16 was sort of a nearly normal year, but after the end of a long drought, a nearly normal year, just sort of holds it. It's just a placeholder. It doesn't get you out of the drought. It just sort of holds so that drought isn't getting a whole lot worse.
And then along came 2017 and it was a big year like this. It just booming with lots and lots of ARs showing up. I think, over the course of the entire water year. As I recall, the number for California was something like 23 or something like that. AR has arrived, so it just was, they came scattered over various months.
But man, it was just a big water year and a big storm year and it complete, that just erases the drought for everyone, except for the folks, a lot of us out there who worry about groundwater too, and that's the place where I've learned never to say the drought is truly over too loud because I, can absolutely guarantee that somebody will stand up and say, but the wells you, the water tables still are a hundred feet down. That sort of thing. To which I have to just sort of roll my eyes and say, you're blaming 50 or a hundred years worth of overdraft of sustained, unsustainable pumping from the aquifers in California. You're trying to blame that on the weather and it's, it's not, it's people, it's agriculture, it's just, we've been doing it so long.
[00:20:06] Bridget Scanlon: So how do you compare this, recent AR families with the 2017, do you think they're comparable, in terms of aerial extent? And then of course you had issues with the Orville Dam and stuff in 2017. But again, I mean if you look at the US Drought monitor, you see the drought ending in 2017 in January, just kind of like it did recently. Yeah. but I realize it's a lot more nuanced than that. And then some areas are not truly getting it.
[00:20:33] Mike Dettinger: Yeah, so comparing the two and it's a real natural thing to do. 2017 is recent enough that most people remember it and it was big enough that it's, a good comparison and it was at the end of a drought, all that stuff.
So it's a good comparison, but so, kind of going down the list, precipitation wise, the December, January, February period, precipitation in that central third of California is generally a little bit more this year than it was in 2017. By that I mean it might tend to not quite 25% more across most of that central third of the state.
So it was, it was as bad if it, one of the things about 2017 is that it, the AR has kept coming for a couple months, after that also, well, as I say, it's snowing outside today and we're expecting a pretty big strong AR that will happen to be pretty warm and rainy rather than snowy over the next few days to a week.
And so, this one's acting a lot like 2017 in that regard too. But anyway, so, it's comparable. I would say plus or minus 15%. Pretty comparable because that's a single number that I'm applying to a broad area. But anyway, so yeah. There are places where we're looking at twice as much precipitation this year.
In this winter, this December, January, February, as in 2017 in that realm. But they're bit spotty and the really big areas like that are actually on the rain shadowed side of the Sierra. On the eastern side of the Sierra, we had this storm sequence. We had a lot of precipitation and a lot of the storms, instead of really kinda raining out or snowing out, as they reached the Sierras, there was snow and rain blowing over, but also the storms just kept raining for a while after they went over the Sierras. And so there's a broad area of Easternmost California where it got a lot more than normal 2017 precipitation out of this sequence. But, In part that's because it typically doesn't get much from them, and so when it gets a decent amount, it's a lot more than normal.
Yes. You mentioned Feather River, Oroville Dam. That's an area where for the most part we're looking at, areas that got, well, they didn't get anywhere near as much. They might have gotten 50%. of 2017 numbers up there so far, at least in the December, January, February period, we'll see as, as March happens and and maybe even into April and such, whether this year catches up.
But I mentioned earlier just that the northernmost part of the state really didn't get to partake of some of this bounty of precipitation that the, central part of the state did. And that's important. Number one. I mean, Oroville, to date has never been in any particular danger of overtopping or getting into trouble this year. And it's filled up really nicely, this year, from the precipitation that we did get. There's that, the other thing to know about why that's important that the northern state didn't get that much per year. Didn't get as much precipitation as in, say, 2017. Is That's where the water, when we talk about California as a state where all the rain falls in the northern part of the state, and all the people use the water in the southern part of the state.
Well, it's that northernmost part of the state that is the source of our federal Central Valley project, which is this enormous system of dams and canals mostly, and that sort of thing that that brings water from the far north end of the state down to all through the Central Valley for irrigation and the like.
And in the State's Water project, geographically, a bigger program or system of dams and canals and the like, that brings water to the central Valley, to the lower southern parts of the Central Valley, but also all the way over into Southern California, down to the urban areas and even out into the Mojave Desert of Southern California.
Yeah, the sources of those are big water systems in California aren't in that northern most part of the state? And I mean, I look at it and I think that, I would've loved to have seen lake Shasta, which is the source of the federal system, get a bit more runoff into it. It's still further down than I would like to see it, but Oroville is the headwaters of the state's system.
It's gotten to a place where it's pretty much, you don't want too much more water in that thing because, you end up having to manage around it if there's ever any flood, floods and that sort of thing. Shasta could take a pretty healthy flood at this point and never even notice it. It definitely is.
has improved a lot. Yeah.
[00:26:06] Bridget Scanlon: I downloaded the data the other day and Shasta was like 61% and Orville was 74% of capacity. So, this pathway for these ARs, was pretty consistent throughout the whole time period this time, so it seemed to follow the same sort of track and the same area got more and more rainfall, so it didn't, it wasn't like bouncing around all over the place.
[00:26:30] Mike Dettinger: Yeah. the way that we look at these things, the way you have to look at these things. There, we talked rivers and narrow bands of vapor transform, that sort of thing. But that's really in a meteorological use of the word narrow. These things are typically, depending on how we define the edges, they're typically on the order of, 800 to a thousand kilometers yeah. North to south, more or less. And that's a distance that is pretty much the distance, more or less between Los Angeles and San Francisco. That's a big area. But yeah, these things, they, these swaths across the central third that I'm talking about really storm after storm this winter is pretty much that LA to San Francisco band. So they really were just sort of teeing off on that particular area through this winter. And, notably, again thinking about this from a sort of meteorologist point of view, would you have to, because I'm talking about storms, is that actually Washington and Oregon have been really notably dry this whole time. So we were, it's not a stretch at all to say we were getting the storms that in an average year we would've at least split with Washington, Oregon, and probably gotten the smaller part of them than Washington, Oregon. And we were just getting them and they just were teeing off on the central third of the state, I have to say, the water from these storms, coming off the ocean, it was reaching all the way to Salt Lake City.
So all the way over into Utah and I saw a map the other day of all the places that had record breaking December, January, February, precipitation totals in the continental U. There's this amazing map that comes across the middle third of California and, you just see lots of stations and the like there that had record breaking totals, not hugely record breaking compared to 2017 or 1983 and some of the other big years. But, record breaking tools goes across, nor more or less northern Nevada in over to, Salt Lake and Utah. And then, the band of record-breaking totals continues on over, oh, clips the, northwest corner of Colorado. And frankly, it goes all the way over to the Upper Peninsula of Michigan. I mean, it just continues on over and frankly, I've got, colleagues at CW 3 (Center for Western Weather and Water) who, we all sort of jumped on this map, which somebody, a fellow Brian up in Alaska had tweeted and I noticed and brought it back to the center and, we've been sort of looking at that and trying to understand, it's highly unlikely that this is actually some AR pathway because there's a lot of mountains and things to bust up and to rain out in the AR once it gets inland very far, it's not rare to see them get to Salt Lake. and it certainly happens that some of them actually make it all the way into the northwest corner of Colorado.
But those are, they're relatively rare. They're just, they're, well, when we see 'em, we kind of hoot and holler and are excited about it. But the notion that it could then pass all the way over the Rockies and keep going is that's just, yeah. I think that's just crazy. But, so we were trying to figure out, okay, what is happening here? How are these things lining up in this weird way?
[00:30:20] Bridget Scanlon: . So, they'll be reporting the snow pack and the snow water equivalent in the near future. Yeah. Is early April one or something like that. But looking at the preliminary numbers, they look really high in the Sierras. I mean, and so you've got a really nice storage there, so that's great.
[00:30:36] Mike Dettinger: Yeah, we've had not unexpectedly, pretty weak. So years during three years of drought to date, and this one is really, there's a lot of snow there and in particular in the southern half of the Sierras, which is the highest parts of the Sierras, that's where Mount Whitney and the highest point in the US is, it's got some pretty remarkable snow pack.
I mean over 200% of normal. For this time of year, and we're rapidly approaching April 1st, which is kind of our benchmark for when we categorize whether a year was snowy or not, is what's standing on the ground in April 1st. And we're getting close to April 1st, and so the numbers start to converge, but over 200% for this time of year, and I believe it's like 180% of the normal April 1st amount.
[00:31:33] Bridget Scanlon: That's great. I mean, that's really a lot of water in the bank, that should get you through the summer and, if it's dry or whatever, Yeah.
[00:31:40] Mike Dettinger: Well, well this being California, let me just take you on a little ride. Everything always seems to have a well, but, attached to it, and, right now some of my colleagues and I are kind of looking at what, at that situation in the Southern Sierra, which drains into the southern two thirds of the Central Valley, and I'm being a little bit cagey there because the way the Central Valley works is the northern third is the Central Valley. The middle third is the San Joaquin Valley, and we tend to think the whole southern part of the thing is the San Joaquin but then there's a large area, roughly equal to the other two in area, each of the other two in the area. That's the Tulare Basin? . And it's connected directly to the San Joaquin Basin, but it's actually a low point in the Central Valley. It's one of the low points in the Central Valley. And so in before development there was a huge, like shallow lake there that was Tulare Lake and with development, one of the big advances is that they started routing water away from that lake. And it, freed up, large area of, agricultural land. This wonderful central valley flat as a pancake sort of, and deep soils land, some of us are kind of looking at the situation and there are fewer reservoirs in the Southern Sierra than in the rest of the Sierra, largely because it's just a steeper part of the range.
And so you can't build big sprawling reservoirs, and so we're looking at this and wondering, my, by my estimates, what that's worth. We're looking at something like three to almost four times as much water in the snowpack up there in the Southern Sierra right now, as there is capacity.
If you dried up the reservoir completely and then said, I'm gonna catch all that water. Well, the capacity of those reservoirs in the Southern Sierra is about a third or a quarter of the amount of water that's sitting up there in snowpack right now. And so, we're all kind of looking and wondering how that water's gonna get out of the system. Cause it's gotta go quite a ways north to get out of San Francisco Bay to get out of there. And we're wondering if you know you're gonna see some, well, if you're gonna, there're gonna be some risks of Tulare Lake, frankly, filling again, which is not a good thing for the agriculture interests. It means some of the lands go underwater and that sort of thing. And historically that was where if you were driving through the Central Valley, you'd see cotton fields and these sort of low value crops, out there in that part of the valley. But, in the past, well, in the past decade and maybe longer, but I think it's accelerated in the past decade, they've changed the crops there to vineyards, a lot of vineyards now, and, now trees, almonds and that sort of thing.
And both of those are now crops that, you plant them and you let 'em grow for. Five years and five years and you start to get a crop out of them. and, in other words, you can't just go in, call this year a write off. If you lose those trees to inundation, you can't just write 'em off for this year and then figure you'll make it back next year and make the money back next year.
Most of the discussion about droughts and agriculture in the Central Valley in the past year, few years has been about how there has been this transition to these higher value, frankly more, more permanent crops in the Central Valley. From a drought perspective, it's like, okay,in a drought you can't fallow, yeah. You can't fallow these things because they will die and you'll have lost 10 years worth of, and you'll put more money into it to keep it going because of the investment. Yeah. And we're suddenly realizing, hey, wait a minute, If in fact, we get into a situation where parts of the Central Valley are flooding due to say, a really fast snow melt from a really large snow pack this year, we had met, we had I was talking with some colleagues and just saying, I really don't remember anyone mentioning the flip side of that problem that in a wet year, they aren't the best thing to have around.
[00:36:21] Bridget Scanlon: I mean, some of the folks in UC Davis, Helen Dahlke and others, I mean, they look at this flood managed aquifer recharge, so they flood those fields, to recharge the aquifer, but I'm not sure, is that fallow land or.
[00:36:34] Mike Dettinger: It's often shallow land or, yeah. Or, that's part of, that's part of why, it hasn't been as simple as just saying, Hey, there's water, there's empty aquifers. Let's do this thing. Right, right. Because you kind of have to figure out where you're gonna let it happen. Because some places you, you end up actually causing damage, right. Other places it's like, well, that land, even though if I lose that crop again, it's like, I'll make it up next year, because there'll be more water in the aquifer and I'll be in a better position if I need to pump the water, that kind of thing. So this, it's these places where you're looking at trees or well trees, pretty much if you view a vineyard as a bunch of little tiny trees. Yeah. And anyway, so yeah, very high, very large. If you wanna, when anyone talks, if you hear on anything where they're record breaking snow pack this year one way, or they're talking about the southern, right. Southern end, and as I say, they, it could be detrimental that part of the Central Valley. It is arguably, and I'm, this is talking with people at our Department of Water Resources as well as other folks. it's not crazy to say, yeah. There's a risk that we're gonna see. Let Tulare Lake, a big chunk of Tulare Lake kind of reemerge for a little while Right. Because I know I'm jabbering, but one more thing that I think you'll like and that, viewed from an even longer perspective. I mentioned, 50 or more years of unsustainable pumping, overdraft in the Central Valley and in California more generally. But in the Central Valley. Well, the southern, the Tulare area is kind of the locus of these major, land subsidence issues. if you pump the water out of the aquifer protection, they, they can hold less weight. And so then it land subsides and in some places it's like 30, 40, 50 feet. I mean, literally, that's not an exaggeration of photos of where they were marking on power lines and the like, where the land surface was at various times in the past. Land doesn't happen uniformly over a large area. It happens differentially, it happens more here, less there, depending on the soil. not the soils, but the geology, depending on where the pumps die on all that sort of thing. And so the land subsidence is differential. And one of the things that ends up doing is taking all these canals and rare channels and the like.
Are how we typically get the water so it doesn't go to Tulare Lake and head it, send it elsewhere, send it around the Tulare Valley, but also send it north up through the rest of the Central Valley. a lot of these things, some of 'em, very precision engineered 50 years ago or 40 years ago, that sort of thing, those slopes and therefore those conveyance capacities, how much water will run through these canals and things to get it out of the area, is really, has really been changed over the past 60 ish years.
Right. On the whole and so the capacity to get water away from Tulare Lake is actually reduced and this isn't me just speculating. This is something that our groundwater folks know, but also our Department of Water Resources that is, that runs the canals and things is fully aware of, is that we've simply, there's less conveyance capacity now than there was in the past just because some places the slope of the canal has leveled off a little bit more, or, I don't think I've ever heard of any places where the canal is actually flowing the wrong way now. But that's, some of 'em are close enough that's not unthinkable in the future. Right. And so in California, everything ends up being totally, just a mishmash. Any problem you think that you can put to the side and deal with later always comes back to bite you later.
[00:40:44] Bridget Scanlon: Right, right. Yeah. So I mean, all of these things are sort of trade-offs and stuff, but, you think something is a big advantage, but then there could be some unintended consequences in other areas. And, yeah, we need to be kind of aware of all of those things and as we try to manage the water
[00:41:01] Mike Dettinger: Talking about the drought busters and I'll just say, yeah, drought busters. When you're looking for a drought buster because you're in a drought, it's like, oh my God, I wish we would get a good wet year. I'm tired of being in a drought.
It's costing, I mean money if I'm a farmer or whatever. Nothing's ever done halfway here, just , So drought busters really are a pain in the behind too. But that's kind of how our droughts end. And so we need the drought busters to get out of droughts, but boy, we wish they would, the drought busters would, settle down a little bit.
[00:41:34] Bridget Scanlon: but I mean, I think that the Murray Darling basin in Australia, has similar issues with those extremes, extreme droughts and then, floods and back and forth, so I understand the state said that they would, transfer maybe 30 to 35% of the water from the north to the south this coming year.
[00:41:53] Mike Dettinger: Yeah. So they, because of the drought, it's not, yeah, this sounds astoundingly small, during some recent droughts, the corresponding number of how much water will be delivered of all the contracts that the state has to deliver water, five, a 5% delivery has gotten to be something that we've seen. Okay. So we're in the drought. That's what that means. And we went into this. This water year, the state was warning that, well, this is, this, if nothing changes, this is likely to be a fire, another 5% delivery year by January. The state had, kind of said, oh no, okay, we can revise that now.
And the number that was on that's on the table is about 35%. So major increase in that.
[00:42:45] Bridget Scanlon: So it doesn't seem like a lot relative to what they're supposed to deliver, but still it's a lot relative to what they have been getting.
[00:42:51] Mike Dettinger: Yeah. you gotta come, you have to understand the contracts, which I won't claim I actually do, but you kind of have to understand the contracts in the sense that it's, I'm trying to think of a good analogy, and I don't have one offhand, but it's a situation where, if I'm a, if I've got a, need for water. If I'm an irrigator, I would rather, have contracts for more water than I would typically use than less. So that nice one, I can get more. Yeah. 35% of a larger number is bigger than 35% of just exactly the minimum I can get away with, And also it's just a matter of, California water supplies.
Just, we're either in a drought where we're looking at, total precipitation, 30% down from where we would nor on average year , or we're in a wet year like this where we're probably gonna end up looking at 170 to 190 or more percent of normal water out there. And it just bang between those two limits.
You can't, it's like water rights you can't get away with. Water rights don't work if you only have as many water rights as the normal amount of water. Because in a wet year you got a lot of water that then no longer has a home. Yes. Slash destination. And so you would rather have more water rights than the normal amount of water, and it's, I think the contracts work that way. As I say, I don't claim to be an expert on the contracts. Right. But that's how I've sort of rationalized the fact. I mean, I don't know, but I've ever heard of a year where a hundred, they said, oh, we're going over a hundred percent. I don't, yeah, sort of doesn't work that way.
That's not what it, that's not what they're intended for.
[00:44:44] Bridget Scanlon: I mean this has been a very interesting few months and, we have, learned a lot and every time we experience these atmospheric rivers we learn more. And yeah, it was great, all the previous knowledge that you had, that you were able to forecast them at least a week ahead of time. You were tweeting them in mid-December and preparing people, and so water managers had a good handle. So, in as much as they could prepare. And so, so that's fantastic. And you mentioned before that these have to transfer, across, the Pacific. So they're sort of self-forecasting. You've all that period for them to evolve and stuff. And, it is great to learn about these things and, really appreciate all the work, that, you are doing in this field and educating us and keeping us informed. Is there anything else you would like to add at this point?
[00:45:32] Mike Dettinger: No, I think I've talked your leg off. No,I think I've said everything I can think of Right. And more promptly, but yeah.
[00:45:41] Bridget Scanlon: So well than you so much for your time. This is, Mike Dettinger and he is at the Scripps Institute and Center for Western Weather and Water, CW three E.
And, look for his, blog posts and other things on ARs. Thank you so much, Mike. Sure.
