2016 Forum: The High Plains Aquifer: Perspectives from Oklahoma

2016 Forum: The High Plains Aquifer: Perspectives from Oklahoma


It’s good to be here. Yesterday I was
getting ready to travel to Tulsa – I had a talk on earthquakes, as usual – so
I’m glad to be here and talking about something else that’s closer to my heart.
But I was explaining to my daughter, she said, “Why do you always have to go places
to give these talks?” I said, “Well I’m important and people want to hear what I
have to say.” But yeah I was gonna follow up with – she’s 11 now so that’s not good
enough for her and she said, “Why don’t they just call you?” So I’ve been
racking my brain for the last day and a half to try to think of ways that I
could be more animated when I speak so that you actually have to see me and I
have to be present to give these talks. I haven’t come up with anything, so….
and I think it’s maybe fitting that I’m the last speaker here because the
Oklahoma story in terms of the High Plains Aquifer and how water is managed
and regulated is much simpler than all of the others. I think we have the
least regulation in terms of water permitting, and we don’t have ground
water conservation districts, groundwater management areas. Wow many
districts do you have within the High Plains Aquifer? About 20, so we’re the
simplest case of all. When I was invited we were
given the task of talking about the general geology and the trends that you
see in the aquifer in your region and then talk about the regulatory controls
and the state laws governing groundwater in the High Plains Aquifer. So starting
with some of the figures you’ve seen already – and I have to apologize here, I
think my references are not always current, but nonetheless you see the
geologic framework here. This is the base of the aquifer in Texas and Oklahoma and
so our groundwater region in Oklahoma encompasses the Panhandle region – there’s
three counties there – and we have about five counties that touch the High Plains
aquifer in this part of western Oklahoma, and the base of the aquifer is important
for understanding the saturated thickness that’s available for pumping,
so as we monitor groundwater levels over time, we will look at the change in that
saturated thickness, and in Oklahoma that’s an important consideration
because we basically will manage and regulate the the volume of water that we
can pump and permit for pumping based on the available saturated thickness. So the
base of the aquifer – and Oklahoma’s highest point is out here in the
Panhandle – so the base of the aquifer actually increases in elevation, as does
the ground surface, to the west. So if you look at the saturated thickness – this
next slide – you see that it varies from tens of feet in Oklahoma in yellow to
four hundred to six hundred feet in green, so it’s relatively thin, in some
areas very very thin, and we have a few places in the Panhandle where the
aquifer is not present – there’s no saturated thickness. So in Oklahoma the
Oklahoma Water Resources Board is the regulatory authority for setting the
rules and issuing permits for groundwater production
and/or surface water use, and it is a legal property tied to the ownership of
the land so if you own 1,000 acres you are issued a permit based on a
certain number of acre-feet per acre that you own per year, and so you have to
prove a few things to obtain a groundwater permit: that you will put the
water to beneficial use – that’s one important piece here – and that waste of
the water would not occur. So what I typically do when I investigate an area
in any state, including Oklahoma, is try to start with a kind of a water budget
and so I have a table that I’ll build out throughout this talk, starting with
of course how much water is in storage in the Oklahoma portion of the High
Plains Aquifer? so that’s the first line there, “A” – we have about 90 million acre-feet according to the Oklahoma comprehensive water plan that was
published in 2012, and the date of the volume there, the groundwater storage, is
in question – I’m not sure that it was actually that volume in 2012 – but
nonetheless that’s the amount of water we have to deal with, and because we
regulate the water as a non-sustainable resource,
we’re basically planning to use that water over a 20-year period of time. The
maximum annual yield (the MAY) is based on issuing permits to use that water in the
20-year time frame, so each landowner will get an equal proportionate share,
that’s their share of the maximum annual yield that they can take advantage of,
and that actually is capped at two acre-feet per acre per year so any landowner
can potentially extract up to two acre-feet per acre per year from their land.
And it might be scaled downward depending on the sensitivity of the
aquifer to climatic conditions and its general trend. So the High
Plains aquifer in Oklahoma has about four million acres of land, and the
recharge rate is very very small – it’s estimated in that OWRB comprehensive
water plan, and the final order that was established most recently for our
MAY, our maximum annual yield, to be less than one inch per year, and so if you do
the math there you get an acre-feet per year rate of two hundred forty four
thousand, very small amount of recharge. So in Oklahoma we do a study of the
aquifer about every 10 years, develop a maximum annual yield, divide up the
water within that aquifer to maintain it for 20 years,
giving the equal proportionate share to the landowners, so in in Oklahoma
the most recent MAY was official in March of 2002, so I’m interested in, if
we are planning to use this water over the next 20 years, where do we stand now
in 2016? So that was my approach here is to try to look at water permits and
water use and then water decline and see how they all match up, and if that water
budget kind of plays out we can learn something about the potential lifespan
of the High Plains aquifer beyond 2022, I guess would be the planned lifespan. So this chart at the bottom shows the number of wells that were permitted by
county and as I said we have seven counties that touch the High Plains
aquifer – the Cimarron, Texas, and Beaver County in the Panhandle are the biggest
users of water, they have the most wells, and everything’s bigger in Texas so in
Texas County we have by far the most wells in the Panhandle. And you can see
those wells that are permitted are shown in blue and just a satellite
image in the background, and then I also have two background colors here. This is
the equal proportionate share for the Panhandle – that was issued at two acre-feet per acre per year so if you own land in the Panhandle you can pump two acre-feet per acre that you own but in the western part of the state – the other five
counties – if you own land your equal proportionate share is only 1.4 acre-feet per acre per year – that’s a mouthful – and I think that has a lot to
do with the saturated thickness. The aquifer is thinner here and the recharge
rate potentially is lower there and the current status is actually
probably better in this part of the state. So you can see Texas County the
most wells, second-most Cimarron County, Beaver County, and then Ellis County has the most wells in the western part of the state. So fortunately all of
those permitted wells are not pumping at the permitted rates, otherwise we would
we would be depleting the aquifer much faster. This is the rates of the permits
as they’ve developed over time, and I’m going to mention here that I’m missing
data in the 1930s and 40s – there certainly were permits issued
back then and water was being pumped, but this is what we have record of. Again,
everything’s bigger in Texas, so that big green wedge is the permitted pumpage
from Texas as it’s developed over time, and so today in 2016 we have issued
permits for 6 million acre-feet per year. And so I’m adding that to my stat sheet
among other things. This is where we left off last time, this is the Panhandle –
these three rows here – 2 acre feet per acre per year, this is the area of the
Panhandle, and this is what I would calculate as the maximum annual yield
for the Panhandle region. My numbers might not match the OWRB’s numbers
perfectly because I just did the calculation with my GIS rather than
referring back to the final order, but nonetheless they’re in the same ballpark,
so about 6 million acre-feet per year can be permitted in that Panhandle
region, and the the northwestern part has a lower equal proportionate share, a
smaller area, and a smaller total allowable permitted amount. So
if I looked at the permitted withdrawals in 2002 when that MAY was issued, we had
about four and a half million acre-feet per year of issued permits, and in 2016
that’s crept up to over six million acre-feet per year. But like I said, we aren’t
using water at the same rate that it’s permitted, fortunately, I think Jim Butler
mentioned this earlier, that we don’t always have a good handle on how much water
we’re using and certainly in Oklahoma we do not. This data set that I’m showing
here, the red bars are the estimated High Plains Aquifer water use from USGS
reports. They generally have a 5-year report of water use – estimated water use
– and so you can see our estimated water use peaked at about 700,000 acre
feet in 1995 and it looks like it’s declining. I’ve estimated water use in
1985 and 2010 because we don’t have reports in those years, so it looks like
our water use is dropping off. Most of the water use certainly is for
agriculture as you see from this pie chart here at the bottom. And then I’m investigating recharge – had
a little project in Ellis County, and they wanted to understand the
sustainability of water in that county so I ran this little recharge model
called “WHAT” and basically estimated baseflow as a proxy for recharge, so you can
see the red is base flow, which means almost all of the creek flow or stream
flow in this area is driven by groundwater. And so to get to the trends,
this is a pre-development-to-2000 trend. These are probably not the correct
publications and this certainly is not either but this is similar to the
diagram that I think Jim Butler showed earlier for a well in Oklahoma in
Texas County, and that is prior to any of my own investigations into the High
Plains aquifer of Oklahoma, that’s the trend that I thought in the back of my
mind was occurring everywhere, but you can see in the western part over in
Ellis County it’s actually going up or it’s holding steady, there’s essentially
no change there. Most of the decline is certainly in the Panhandle in Texas
County. And so as the only hydrogeologist in the state of Oklahoma
I often have to do a quick and dirty look at what the trends are in different
aquifers, so this was my first attempt to do that. I looked for data on NWIS to
look at the longest-term trends that I could find for the High Plains Aquifer
and this is the one that I could find. It goes back to 1956, and you can see all of
these wells are primarily up here in the Panhandle and they are all declining
pretty steadily. Now when I did a more focused study in Ellis counting, these
wells here, I found that most of those were holding steady,
not really declining so much, so I was validating some of this data. And what I found is the average water level decline aquifer-wide is about 10 feet over this 14-year timeframe. So adding some more things to my table here – and
I’m going to wrap it up in the next slide – I estimated the recharge rate
using that WHAT model and looking at baseflow, and I think the
recharge rate is much lower than even 0.7 inches per year. I think it’s 0.08 inches per year in that region and that would mean the recharge rate
aquifer-wide would be even smaller. And what I see in the change of
storage, if I map it out I get about four million acre-feet decrease in storage
from 2002 to 2016, which is pretty close to our permitted withdrawals in 2002, and
consistent in a sense with the declines that we saw in this time frame. So things
are making sense – this is kind of just a wrap-up slide that shows the change in
water levels in Oklahoma from 2002 to 2016. I used about 87 wells to run this
just the other day, there’s roughly 200 that are accessible from NWIS that I
could incorporate here, but the declines, the largest declines are obviously in
Texas County and down here in Cimarron. I’m gonna blame this one on Texas, I think
they’re doing something here, we need to investigate further, but we do have
some areas where we have very little decline or actually an increase in water
levels over time. And I’ll wrap it up there – thank you.

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