Here in Virginia,
there is an old saw about smallmouth fishing: when the leaves on the dogwood
are the size of a squirrel’s ear, it’s time to hit the river. For those
of us who go fishing regardless of the size of a squirrel’s ear, the information
is interesting but not critical. I for one have stopped trying to get the
squirrels to hold still long enough to make the comparison. That’s because
information is only as valuable as it is useful, and only as useful as
it is convenient.
In a recent article I quoted
river levels, rising and falling trends, temperatures, water clarity, and
the relationships between two major and several smaller tributaries in
the stretch of the Potomac that I fish, all in concrete numbers and all
for exact times of the day and night. A friend read the report and asked
me a simple question: “How the hell did you know all that?” For him, of
course, I just smiled inscrutably and let the impression flourish that
I had some mystical connection with the river gods. More like Rivergods.gov,
better known as the United States Geological Survey.
If information is only as
valuable and useful as it is easy to obtain, the USGS Real-time Streamflow
World Wide Web page is the ultimate source of information for river anglers.
With a bit of practice and some background, this resource can revolutionize
what you know about river fishing, and, I suppose, squirrels. Oh, and it
can save your life.
http://waterdata.usgs.gov/nwis/rt
Stream gaging is a major
activity for the government. (‘Gage’ is a variation of ‘gauge’.) Next time
you hear someone disparage the value of government, remind them of what
every citizen should know: there are 7,992 stream-gaging stations maintained
by the USGS and subsidiary state and local government agencies. That means
that at 7,992 points on American waterways--rivers, creeks, and a few reservoirs--a
mechanical device measures the water level and transmits it regularly to
the proper authorities, and, through them, to you. (For particular information
on the nature of these devices or any other information regarding the stream
gaging program, consult my primary source: circular 1123 of the USGS at
http://water.usgs.gov/ pubs/circ1123/). What’s really cool about this system
is the satellite uplink. Anybody with any sense can go to the river and
judge its suitability for fishing or wading, but in these fast modern times
to be able to access the river levels--here, there, and everywhere, where
they’ve been and where they’re going--is an invaluable resource for an
angler.
A bit of history and
purpose
The stream gaging program
serves many masters. In the west, where water rights can be matters of
life and death, minor changes in some stream gages are litigated like the
Microsoft breakup. Anywhere there is a large body of data (the majority
of stations have over fifty years of record) flood conditions can be predicted
with excellent accuracy. And long term river flows are extremely useful
to a huge number of research projects on every topic imaginable. In fact,
on the USGS list of uses for stream gaging, fishing does not appear. But
make no mistake, it’s your tax dollars at work.
In the old days, before
the invention of volcanoes, the lava had to be carried down the mountain
in buckets and poured on the sleeping villagers by hand. Before the invention
of remote stream gaging, people checked the gages, took the data down by
hand, and archived it. The present WWW page can access data from some stations
that is over 100 years old. The majority of stations came on line in the
past fifty years with the invention of remote gages that can be positioned
well away from the stream. Later inventions allowed data to be transmitted
by telephone from the gaging device to offices or other comfortable locations.
The real revolution came
with the cheap development of satellite uplink technology. This allowed
great flexibility with gaging stations, and permitted the hydrologists
to place gages in locations that suited their needs, not in locations that
were convenient. Some gaging stations are in quite remote areas and are
very rarely touched by an actual human being. For flood control this makes
obvious sense; when there’s a flood, when you need them most, it’s tougher
and more dangerous to take accurate measurements. Also, in places where
water rights are hotly contested, taking the human being out of the loop
makes it easier to secure the data and keep it reliable. Not to mention
the main reasons: machines are more reliable than people, and we want it
now, not when you get around to putting on your hipboots and starting up
that truck.
"If information
is only as valuable and useful as it is easy to obtain, the USGS Real-time
Streamflow World Wide Web page is the ultimate source of information for
river anglers."
The internet revolution
was the next step. In the eighties and early nineties, river level information
was available via a phone connection or on NOAA (National Oceanographic
and Atmospheric Administration) weather service broadcasts. In these cases,
however, the data was point-time; one gage level, which might be stale
by hours, and a prediction: falling, rising, or stable. They had more data,
but no easy way to convey it. Still, it was a great asset at that time;
the only alternative was to call someone by the river and have them look
out the window. With the internet uplink, the range of usable data for
anglers has exploded. There are some caveats, however. The main one concerns
the accuracy of the gages. Obstructions, ice, vegetation, and other accidents
of nature can affect gage readings. The devices themselves are somewhat
unreliable and accuracy declines between calibrations. It is important
to remember that these stations provide raw data and are no substitute
for caution and good sense. It goes without saying that the USGS and the
other organizations that provide this data accept no responsibility for
its use or misuse.
Uses, abuses, confuses
For fishing, the basic rule
of stream gaging is that experience makes the data most useful. To use
the gauges, you have to know how the numbers affect the river. The simplest
use of stream gaging technology is to judge the river level, or “stage,”
at that moment, in what the USGS calls “realtime.” One drawback to this
simple application is that gages are not on a normed or consistent scale.
5.5 feet at Harrisburg at noon on the tenth of March may not be equivalent
to 5.5 feet upriver at Sunbury or downriver at Marietta.
In fact, 5.5 feet at Harrisburg
is roughly equivalent in flow and level to 11 feet at Sunbury and 38 feet
at Marietta; those values do not reveal the terrible course of a wall of
water bearing down upon Bob Clouser’s shop, carrying the drowned fragments
of the Riverfront Campground and the Pennsylvania State Capital in its
terrible foaming maw. They represent stable/gradually falling levels on
the Susquehanna. To use a gage you must be familiar with the actual river
conditions as they relate to river level.
Another factor is the relationship
between river stage and flow. Both are simply different forms of the same
data, but the way that data affects fishing is up to you to judge. The
term “discharge” is used to describe the total amount of water passing
the gaging station per unit of time, usually expressed in CFS or cubic
feet per second. To understand discharge, simply imagine that the gaging
station is at the end of a large pipe; in reality, the water isn’t really
being “discharged” anywhere except down the next bit of river.
The relationship between
discharge and level is complex, just as the relationship between distance
and miles per hour is complex. This is the logic that every kayaker follows;
as level increases, so does the speed of water movement and, if you’re
a good kayaker, so does the fun. Therefore each additional foot of stage
multiplied by the number of feet across the river at that point doesn’t
translate simply to another cubic foot of water per second; the time it
takes the third (cubed) foot to pass the station has decreased as the flow
rate of water has increased. They learned this hydrological lesson the
hard way on the Mississippi--higher water goes faster. So a key river station
for our outfit, Paw Paw on the Potomac, a foot of rise in the midrange
of flow levels translates to a discharge increase of about 1200 CFS. For
the Harrisburg station on the Susquehanna, a foot of rise in the middle
range of flow levels translates to a discharge increase of about 18,000
CFS. A one-foot rise at Harrisburg equals a discharge increase of nearly
four times the total flow of the Potomac at Paw Paw. That’s a big river.
As I write this the Susquehanna is at 10 feet, about 137,000 cubic feet
per second of flow.
At low levels, of course,
another effect is present: zero flow. Gages are located and equipped with
different purposes in mind. Those on hotly contested streams in the West
tend to be more accurate as flows decrease; most Eastern gages are mainly
to collect data for flood control and monitoring. Therefore some of our
gages--including two that would be useful for my guide service, Harper’s
Ferry and Shepherdstown--don’t even function when the river is at low or
normal flows. Since we guide mainly in the warmer months, when low levels
are typical, the gage is too simple to be useful: if Shepherdstown is registering,
we don’t fish. Unfortunately, when the river flows are low the gage plays
a very important role. When the flow is very low small changes in flow
can make a large difference in fishing. That leads to a rule: for high
water we care about river level; for low water we care about change. An
application is obvious. In the Susquehanna, and to a lesser extent in the
Potomac, a summertime rise can hurt fishing. If the river is at 4 and the
gage rises eight inches, the effect will be much less than if the river
is at 2 and the gage rises eight inches: the proportion of rise to flow
is much greater in the latter example. Of course, the basic rule still
applies: Know your gages.
Better and deeper and
faster
The best value of the gage
pages is their ability to keep data in a historical perspective--from days
to decades. Couple that with an intimate knowledge of your watershed and
you have a tremendous forecasting tool. An example: in 1994 I met a client
despite my worries about the river conditions. It had rained hard and long
in the Potomac basin well upstream of our float section, and I was worried
that the river wouldn’t be fishable. News from the gages was sketchy and
inconclusive; I feared that there was a lot of water coming down but I
couldn’t track it. Unfortunately, I couldn’t contact the client soon enough
to pull the plug on the float so I drove out to the river anyway. Once
there I was surprised to find that the level hadn’t changed much and the
clarity was still good. We discussed it and decided to go ahead with the
trip.
We weren’t long out of the
gates when I saw an odd sight upriver: what appeared to be a flock of seagulls
riding down toward us. It wasn’t seagulls; it was a flotilla of trash,
mainly white plastic bottles and styrofoam, the first stuff to break lose
and float down when the river comes up. The white wave was the harbinger
of a sharp rise, and within an hour the river conditions had deteriorated
sharply. A sharp summertime rise can produce a window of good fishing for
big bass along the more obvious shoreline cover; in the first two hours
of the flood we boated six smallies over 17 inches. But then it became
a boatride worthy of an amusement park. We passed Harpers Ferry at a river
level of 8.5; ran Whitehorse Rapids in a brown muddy maelstrom (What’s
a class IV rapid with logs and propane tanks in it?) and went flying down
the Brunswick lake watching for cottonwood blowdowns that would surface
behind us like U-boats. At the ramp I rowed the boat up onto the trailer
without moving my truck. (OK, that’s a slight exaggeration.) That day the
river came up from 3 to 13 in about eight hours.
With the current WWW pages
I’d never be caught by surprise by such a change. The gages are spaced
up the river at intervals that allow you to track the approach of a “slug”
of water and make an accurate prediction of what might happen on any given
day. Needless to say, I was glad to be in a very solid whitewater raft
with a good knowledge of how to handle it on that day; a jet-boater or
canoeist would have had to break for the shoreline or sprint downriver
to escape the flood and its dangerous cargo of trash.
More common is the practice
of assessing the effect on your stretch of river of the past several days
of weather. If you can index that to previous experience on the river,
you can eliminate much doubt about the conditions you will be fishing on
any given day, or even time your trips to coincide with optimum conditions.
You don’t even have to go fishing. If you drive over your river or take
a turn past the boat ramp, then check the river level on the computer--bingo!
Information!
Where are you and what’s
coming your way?
Remember the effect of the
position in the watershed of the area you want to fish. The more gages
upstream of you, the more reliable your data. There are two reasons for
this. The obvious one is that more stations equals more data; the less
obvious one is that the higher in the watershed you are, the more volatile
the stream conditions will be. Last spring I made a trip several hours
to fish a small stream in southwest Virginia. The night we arrived, we
were dismayed to find that the river was out of its banks and clearly unfishable,
even though we’d been closely monitoring the gages for the previous week.
The next morning, however, the river had fallen enough to fish, and one
day later it was in perfect condition.
On the other hand are the
largest rivers, especially the Susquehanna. Things happen very slowly up
there. You can see trouble coming for days in advance, and the profusion
of tributary streams and main-stem gages gives you plenty of data to assess
change--perhaps even too much data.
Another interesting effect
of gages occurs in large main-stem rivers. At Duncannon, where the Juniata
joins the Susquehanna, the river is nearly 3/4 of a mile across. Often
one or the other river will be affected by a rise, but the river is so
large that the water mixes slowly and I have often run an entire float
trip down one bank or another to avoid very different conditions on the
other side. Also, it’s possible to look at the condition of tributary streams;
even after downpours muddy the water along the bank you can find a stripe
of clear water in the middle of the river, and it may be that boundary
line between clear and stained water that is most productive. Catfish anglers,
for example, might watch the gage for that first sharp rise and head for
the river to meet it.
Remember also that the gage
can defy simple observation or logic. At Harpers Ferry, the midpoint of
our usual float trip, the Shenandoah joins the Potomac. At the mouth of
the river the two flows seem equal, but they’re not; it isn’t always clear
where the most water comes from, and it’s easy for us to forget that the
Shenandoah is much smaller than the Potomac (see table.) Add to that the
fact that the Shenandoah and Potomac watersheds are separate enough to
have quite different rainfall and you have a really useful application
of real-time gage data as long as you understand the relative discharge
of the two rivers and take that proportion into account.
Another key consideration--and
another situation where experience is the best teacher--is the effect on
river levels and water clarity. Sharp rises in the summer; rainfall after
drought; gradual rises; secondary rises--all have a particular effect on
water clarity. That perhaps is another article but it is generally true
that the higher in the watershed, the clearer a stream will run and the
faster it will clear. Also, of course, certain tributaries are notorious
for running dirty at the least provocation. The Monocacy near Washington
is one of those; if the Monocacy is high, or even a bit above average,
it will contribute significant mud to the Potomac. The same is generally
true of the Shenandoah, though it’s a different kind of mud--agricultural
vs. silt. Therefore a gullywasher in the Doah basin in high summer might
lead to an algae bloom, thanks to the continued practice in Virginia of
fencing cattle pastures down to the water’s edge to give the cows a way
to cool off on those hot summer days. That’s another article, too.
In the Washington area,
weather often breaks on an east-west axis, so that rainfall can differ
sharply just fifty miles to the west. Add to that the tendency of streams
in the area to muddy up fast due to development in the suburbs, and you
have another use of the gage for our guide service. A simple observation
of the river at the Cabin John Bridge on the Washingon Beltway might be
misleading until you check the gages upriver and compare that to the flow
of the major local tributaries such as the Monocacy River. It may be that
the river you are aiming at--say, the Shepherdstown area of the Potomac--is
actually fishable even though the eyeball evidence downstream is bad. Again,
it’s the habit of use that makes the information more valuable.
Where, what, when, and
how
The first-time visitor to
the USGS main webpage for river gages might be intimidated. On the other
hand, you should know what you’re getting into. Judge according to your
own appetite for technology and computer use. In the paragraphs below I’ll
talk you through the entire architecture of the site and also supply you
with the simple URL’s to get what you need quickly and get out so you can
leave the computer and go fishing.
The USGS site is quite streamlined
and clear considering the source; since the USGS is a government agency,
it has certain bureaucratic tendencies. When you remember that it’s handling
an enormous amount of information updated in 15 minute intervals and kept
forever, the clarity of the site is pretty impressive. At http://www.usgs.gov
you will hit the home page of the United States Geological Survey. At this
point you can go three ways: use a search utility, surf in an orderly fashion,
or wander haphazardly around until you hit something interesting. If you
have a particular river, region, or station in mind, you may have to make
a more careful approach; it’s a big domain.
The best approach is to
find the sites you want and bookmark them, but the site designations are
not set up for convenience. Each site is given an 8-digit designation to
distinguish it from every other site. This is useful when you remember
that there are lots of Black Rivers and Muddy Creeks in the country, but
tough when you want to search for a particular gage out of the almost 8000
that are out there.
Furthermore, sites are indexed,
organized, and funded by state. The Potomac is a border river for West
Virginia, Virginia, and Maryland at various points along the way; yet,
due to the pre-revolutionary agreement about the river, Maryland owns it
to the high water mark on the other shore. Therefore gages on the east
bank may not appear on the same web page as gages on the west bank because
the states in question may not be inclined to undertake the expense of
maintaining a gage on somebody else’s river. Of course, the floods don’t
respect the fine print of a 350-year-old land grant. Anyway, some states
spend more energy and money on gaging than others so Potomac gages in West
Virginia appear on Maryland pages, which is fine because West Virginia
gages are less reliable and less accurate than the Maryland gages. Experience
and a little research will reveal how your state and watershed line up.
Recent organizations of
this data have grouped sites more by river than by administering authority,
but it’s still not easy to find every useful site. One way is to navigate
your way to the Real-time Water Data page (http://waterdata.usgs.gov/nwis/rt)
where a large clickable map is displayed. The key steps: From http://www.usgs.gov
hit the “water” button at the top of the page; that takes you to http://water.usgs.gov/.
Once there, choose “real time” and go to http://waterdata.usgs.gov/nwis/rt.
Remember to bookmark well; these pages are large and take a long time to
load. I keep the realtime page on my bookmark list for when I am curious
about locations that I haven’t fished before, and I occasionally check
up on sites I fished and loved long ago, much the same way we occasionally
look up old girlfriends in the phone book. (What? You don’t do that?)
Before clicking on the map,
note below the map that you have choices: ten closest gages, state list,
or state map. You can also scroll down to the rack on the left and hit
your state. The main problem here is that the map is small and choked with
sites, and it’s sometimes tough to hit the right spot in the east where,
I am proud to note, there is a whole lot of gagin’ going on.
The return from an area
click will be arranged in distance from the point you hit; that can make
for some confusion about the actual location of the sites you’ve found.
One way to check is to go to the page and read the fine print on the gage
location. Some pages include a link to a map of the drainage area and other
interesting data, usually found under “Historical daily mean or peakflow
data for this station.”
Another approach is to navigate
through by state, which is easy if your river isn’t a border. Eventually
you’ll wind up with a list of stream gages arranged from upstream to downstream
along each branch of the river. Become familiar with the place names of
the gages, monitor their changes, and you will be linked up. State and
national maps are interesting in that they give a quick picture of the
flow situations. Each station is represented by a dot; the color of the
dot signifies flow relative to historical averages (actually means; “mean
daily exceedance” is another measure of daily flow relative to the history
of that site). At the moment the national map reflects low to very low
water from Texas to Michigan and high water to record high water in the
mid-Atlantic, especially in the Appalachians and around Philadelphia. If
you are a flexible angler, more willing to change locations than fishing
days, these maps allow a quick glimpse of the “big picture”. All the maps
are clickable for the particular gage situations.
Once you are on individual
gage pages, the data becomes more directly applicable to fishing conditions.
Remember to bookmark the site, but be careful; some web browsers only record
url (web address) and title, and the title probably won’t refer directly
to the station--the text of the web address, which the computer copies,
isn’t set up for convenience. You’ll need to go into your bookmarks and
title each one in your own words. For example, before I edited the title,
my bookmark for Susquehanna at Harrisburg read “Hydrograph and station
description for 01570500” which wasn’t much use.
Each page has three main
representations of data: stage, discharge, and exceedance. Stage and discharge
are charted on a weekly interval; that is, the line of the chart is always
seven days old, with one day of space ahead of it so you can extrapolate
the level. Running across the chart is a blue line to represent the water
levels. On the flow chart the mean levels are represented by blue triangles.
Remember that these are means for the particular day of the year, which
is how much of the data is organized. Exceedance is also a measure of daily
flow over years of record in cfs. Each page also has a ton of basic information
about the gage sites, which can help you to decide if it’s the right place,
or even help you to find the gage on your next trip down the river. I once
was astonished when I searched the web and found a certain river running
at a tiny fraction fo the flow I expected, and it took me a few minutes
to realize that I was looking at a different river of the same name in
Wyoming.
From these pages you can
access great piles of data on that site. To illustrate the disastrous Potomac
floods of 1996 (and the very high flows all summer between them) I have
downloaded the entire year’s data and charted it to quantify the term we
used that summer: crappy fishing. (4-foot banner versions of this chart
are available.)
An Easy Starting Point
A simpler and more elementary
source of river condition data is the web page of the Middle Atlantic River
Forecast Center, or MARFC. Operated from an office in State College, PA,
MARFC organizes a diverse set of data including river levels, precipitation,
and water temperatures in a concise website at http://marfchp1.met.psu.edu/Forecasts/WBC/index.html.
For levels and stages it is useful though less thorough and sophisticated
than USGS (from which it gathers its gage data) but this site is excellent
for one other bit of information: water temperatures. Especially in the
spring and fall, temps are hugely important for us smallmouth anglers.
The temps are only measured and reported for a gage site well down the
watershed but it’s a simple matter for us to extrapolate with experience
and jump on those critical windows of rising temperature.
Whassup?
As I’ve said a bunch of
times, the key element to this resource is the user’s built-up fund of
experience and understanding of the data represented there. For the most
part that data is highly specific to the locations you fish, but there
are a few details that might help you to judge what’s up with your river.
One detail concerns upriver obstructions to flow, most specifically dams.
Most of the rivers in the nation are affected by dams, and familiarity
with the effect of dams can explain much about river conditions in your
area.
The most obvious dam effect
is the stair-step. This is a very distinct change in flow as it is dictated
by the dam release. A flat, stair-stepping line is common data from a gage
that is located very near a dam. This is important as it affects fish behavior,
habitat quality, and safety. A good example of this effect can be found
on the Jackson River in southwest Virginia, which is entirely controlled
by the flow from Gathright Dam. The Jackson is an excellent trout tailwater,
but it is also the conduit through which water travels to a massive papermill
in Covington, VA. (and away from the papermill, carrying far fewer trout
and far more other stuff.) Because the dam and river exist for more than
just trout, the dam releases and river levels are not entirely logical
to the trout fisherman (though the trout don’t seem to mind as long as
the bugs keep coming.) Jackson River levels can take on some oddly uniform
shapes.
Even a great distance downriver--all
the way into the James, the river that receives the Jackson’s flow--the
effect of these releases can be seen as regular though by now a bit fuzzy
changes in the river level--unless a tributary between the dam and the
gauge delivers a slug of water. Another example of that, common here in
the East, is the effect of diversion dams--obstructions which do not completely
control the river flow but either hold and release some water or divert
some water for other uses. This often causes the distinctive “heartbeat”
pulse on the gage when river flow is momentarily held, then released. These
pulses are very distinct at the dam and for a few miles below; how they
affect fishing is another question.
In the chart the actual
river flow is clear if the spikes are factored out. There are other significant
causes of gage variation, including accumulation of vegetation, ice, or
debris; changes in generation needs during peak or low use periods; flood
control; even accommodation of construction or recreation needs in the
watershed.
During the past summer’s
historic drought, river levels on the Potomac were supported by releases
from the Jennings Randolph dam--over 100 miles upstream. Though we benefitted
from the water, it was mainly intended to keep the residents of the Washington,
DC area clean and well-hydrated. The releases were visible only in a gradual
uptick of the river level from its lows of about .68 feet up to about 1.4,
then back down over a twelve hour cycle. These examples of local or particular
variation are only intended to illustrate again the need to use these pages
with a grain of salt, and the best seasoning is experience. I’m sure it’s
possible to have too much information, but why ignore it when it’s there
and it’s free?
As I write I’m looking ahead
to a trip in three days, and I need my gages. It rained 1 1/2 inches here
yesterday, and though we’re in a drought that’s a lot of water in the creek.
The outfitter has just e-mailed me to say that the river’s up; the clients
are worried that their trip will go off. It’s early season; I want conditions
to be just right. In the next 48 hours I’ll be able to make a very confident
prediction about river levels, water clarity, level change, and even temperature,
and satisfy everybody. Without looking at a squirrel or any other rodent,
except perhaps a mouse.