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How to Use the Stream-Finder


Months Ahead, A Few Days Ahead, Hours Ahead


This set of directions should be used with the Stream-Finder guide to figure out the likelihood of which streams will be running months in advance (in case you’ve promised your local canoe club to lead a trip)  in the near future (like, a week), or within hours.  The Stream-Finder, is meant as an improvement on the popular American Whitewater website, here in the Washington-Baltimore area.  Here is how:


On AW, those streams in spate are nicely highlighted in green, those too low in a pinky-brown with links and all the rest.  While this works, it has several problems which this guide, also web-linked, seeks to correct or avoid.  While AW links each stream to but one USGS gauge, this guide sometimes uses on-line gauges on several creeks – the Lost uses 5 gauges, and Gaither Gorge uses 3. Too often AW gives the USGS gauge’s measures in feet, whose meaning is obscure to newbies and paddlers from out-of-area, whereas this guide uses the universally comprehensible and comparable cfs (cubic feet per second).  Reflecting the paddling community’s ancient custom, stage readings are retained for sections like Little Falls, the Staircase, and the James Fall Line.  The Stream-Finder groups the streams by watershed and by region to make a choice quicker.


A bit more challenging to use, the tables put you in charge as you select your stream. Here is the URL to put on your desktop:  LINK   If you lose it, look for it on the websites of local paddling clubs:


on the CCA website under: Trip Schedule,

on BRV: at the bottom of the home page or under Paddling Resource Links, Col 1, and

on MCC under: River Levels at #23 at the bottom or

under Canoe Clubs and More, at Personal Paddling Pages.  


Now for the steps:


Long Before The Trip


1 – Set up your own USGS Water Alerts – “In time of peace, prepare for war.”  Before the rains fall, arrange to get them sent to you by USGS when your favorite streams pump up into a navigable volume (above the minimum).  Go on the USGS site and on the particular gauge page you want to access – under Current Conditions/Historical Observations, look below and to the right of the gauge table for the Water Alert link.  Enter the minimum cfs you need to run the stream.  Some gauges ask you to enter your minimum reading not in cfs, but in feet.  If so, you must go to the two-column table for that gauge and by looking up and down, sometimes for months, to obtain that equivalent for your desired minimum cfs figure.  I have 17 ready to ping my e-mail telling that x, y, or z stream has just exceeded my designated minimum.


2 – Check the Average Volume of your stream on your desired date. GRAPH In USGS that is reached by scrolling down from the familiar Current Conditions/Historical Observations, to the next slot, called Time series: Daily Data.  Here you choose “Discharge, cubic feet per second.”  Set it for as many days as you need and set the right hand Output Format button on Graph w/ stats.  On the graph pay attention to the yellow line, which gives you the “median daily statistic” over the life of the gauge (for Buckton – 82 years). For a Table giving 365 days of such figures (the mean discharge at each gauge since it was installed) on the Summary of all Available Data, click on Daily Statistics.  On the baby blue screen that results, ignore all the choices under Choose Output Format and click “Submit” at the lower left.


A third way is in your USGS Real Time Stream Flow (see #5, below) shown by the string of small yellow triangles arrayed along with the blue line showing the hourly/daily discharge (volume) passing the particular gauge.  Say you want to lead a group down Passage Creek in mid-August. In the Stream-Finder click on the relevant gauge (here: Buckton) and the yellow triangles indicate that the average flow in that month is just 14 cfs – far too low, as the S-F tells you that [150 cfs] is the minimum for that trip.  And, remember, in most cases, you’ll have more fun at volumes twice the minimum or more.



A Few Days Before The Trip


3 – Look at the QPF – Quantitative Precipitation Forecast – for 2-5 days ahead - [on the Stream-Finder’s home page click on Weather Appendix, and go to #3 b.] DEAD -->    These maps with the green and blue amoeba blobs tell when and how much the rains will be. 


4 – Check the Local Forecast – On the left of the QPF page – type in the nearest City and State, and up come nine little pictures of weather happening – under which is your “Detailed Forecast.”  Over on the right is the Radio & Satellite Images - with the map with the Sterling Loop  and the Hourly Weather Graph  -  rich with wind, temperature, precipitation, relative humidity, chance of precipitation, and even wind chill data - by the hour.  Pass your stylus over the chart to the time of day you want, and you will see the values also displayed below the several charts.  On the chart two days worth of data are displayed – for farther into the future, above and to the left of the charts - at “48-Hour Period Starting:” click on the “Submit” button.  Or at the top right, it offers tabs saying “Forward 2 Days” and “Back 2 Days.” You can also display these numbers in tabular form.  Go one table below this for the vertical green bars predicting rainfall by the hour – and summing up how many inches may fall in a certain period.



Just Before the Trip


5 – USGS Real Time Stream Flow No more predicting, we’re ready to find out what’s running right now.  So return to the Stream-Finder home page and go to the stream tables by clicking on the name of the State where your hoped-for brook dwells.  When the tables appear, click once again on the large blue or purple state name to get the stream flow.  These are the maps with the blue and green, etc. dots for the gauges telling relative volumes on that date.  N.B. They can indicate, but do not promise, that there is sufficient water in the particular creek.  You can push the + or - sign to expand or contract the maps.  The lay of the black or dark blue dots indicates where the chances of water are best (or where to stay away from – and wait until tomorrow).


6 – Using the Stream-Finder Tables In the Stream-Finder go back to the State table in which you’re interested.  In that portion of the tables, click on the gauge that relates to your stream.  Be guided by the square-mile figures as to where to look for a likely brook – with more rain falling or snow melting outside – look at the smaller creeks and higher on any particular one.  Compare the real-time gauge reading on USGS with the “Min CFS” shown in the S-F’s next column telling the lowest volume at which the streams can be run.  On the USGS graph, look at the steepness of the line depicting how fast the water is diminishing and figure if you can get there in time (incl. setting shuttle).  Some streams (in Baltimore: Gwynns Falls, Jones Falls, and Herring Creek; around DC: Pohick Creek, Cabin John Creek, and Pimmit Run) often have to be run in the rain.  For that reason, in the last column there are links to various rainfall gauges – see also the WEATHER APPENDIX - #5.


7 – Longer Streams The Potomac, the Shenandoah, the James, and the Rappahannock/Rapidan have multiple USGS gauges, so a bubble (an unusually large volume of water from a rainstorm, snowmelt, or dam release) often can be traced for several days from upstream to paddling favorites like the Needles, Little Falls, the Fredericksburg and Richmond Fall Lines, or the Staircase.  At higher levels, of course, the rivers run faster.


a - Potomac – The upstream Point of Rocks gauge tells what will be at Little Falls in another 9 hours.  Above that is a 40-hour stretch leading down from the Hancock gauge.  The typical 1,000 cfs release at Bloomington (Barnum) or the next-door Savage takes roughly 6 days to reach Little Falls.  And don’t overlook flows from the Monocacy (Jug Bridge) or releases down Seneca Creek (Dawsonville).


b - James – For the Fall Line, look upstream to the Cartersville gauge for what should happen at Richmond in 17 (14) hours.  Another 16 (13) hours upstream, the Scottsville gauge is also indicative.  (The figures in parentheses are for swift running high water [6,000 cfs]).  Above that are multiple gauges, but intermediate dams can trip up these calculations.


c - Shenandoah South Fork – For the Staircase, the gauges upstream from Millville (3,041 sq mi) are Front Royal (1,634 sq mi/ 20 hrs), Luray (1,372 sq mi / 20 hrs), and Lynnwood (1,079 sq mi / 8 hrs), plus, near Grottoes and Port Republic, a threesome (951 sq mi) of the South, Middle, and North Rivers. So the Lynnwood gauge foretells Millville two days before, as does the Mt Jackson (508 sq mi) gauge on the smaller (800 sq mi) North Fork.


d - Rappahannock-Rapidan – For the Fredericksburg Fall Line, look upstream to Kellys Ford (Remington) and Culpeper on the Rapidan – each about a day away from Kellys Ford.


8 – Small Creeks – (4-50 sq mi) and any urban creek – These run out of water fast (“flashy”), so you must act fast – within three hours of a rainfall in some cases.  Once you start looking for these, you’ll be sadly impressed at how often rain – falling at around 6-9 PM – will have peaked in these brooks and be gone by morning.  If you want to bag a rivulet, you must be ready to ride at crack of dawn. 


9 – Orders Of Magnitude - Choosing By Stream Size – Here, in descending order of likelihood that there will be sufficient water, are the choices:


a - The Big Three – As the rains taper off at season’s end, for whitewater there are only three major games in town – and for two of them you must drive far:  First is the Lower Potomac (11,385 mi²), with Little Falls (Cl. III), the Chutes, Anglers to Lock 10 (Cl. II), Violettes Lock Loop (Cl. II), and Mather Gorge, (Cl. II+) – which are always up. Also the James Fall Line (6,753 mi², Cl. III) and the Lower Yough (1,029 mi², Cl. III+).


B - Mid-Sized Rivers are the next most likely: – Rappahannock Fall Line (1,600 mi²), the Potomac Needles (6,311 mi², Cl. II) and Shenandoah Staircase (3,041 mi², Cl. II (III) at Harpers Ferry, Monocacy River (817 mi², Cl. I), S. Br. Shenandoah (various, see 7c above), Brandywine (Pa+Del) (300 mi², Cl. II+)


C - Dam Controlled Rivers – Upper Gunpowder Falls (81 mi², can flow unexpectedly in August and September), the mid Patuxent - fairly constant flow (79 mi², 80 cfs, Cl. 1) at Brighton Dam, and the Savage at natural flow; Seneca Ck (101 mi², Cl. I), the Stonycreek, Pa (450 mi², Cl. III), the North Anna (~450 mi², Cl III), the Lower GPF (340 mi², Cl. III) and, of course, again the Lower Yough (1,029 mi², Cl. III+)


D - Smaller Rivers – Patapsco (dam influenced – 285 mi², Cl. I),  Antietam (200 mi², Cl. II),  Codorus (266 mi², Cl. II+),  Casselmans (382 mi², Cl. II+),  Maury (~300 sq mi, Cl. III+), Rappahannock at Kellys Ford (619 mi², Cl. II+), Goose Creek (340 mi², Cl II+) CURRENTLY OFF LIMITS , Cedar Creek (56/100 mi², Cl. II), Potomac So Fk, So Br (Moorefield Canyon) 100 mi², Cl II+), Hopeville Canyon (No Fk, So Br, 304 mi², Cl. III), mid Cacapon (330 mi², Cl II+), Brandywine, Pa/Del (300 mi², Cl. II+)


E - Large Creeks – Muddy Ck, Pa (138 mi², Cl. II+), Lost R (177 mi², Cl. II), Passage Creek (83 mi², Cl. II+), Marsh Ck, Pa (75 mi², Cl. II+), Stony Ck, Va (75 mi², Cl. II+), Middle Hughes (43 mi², Cl. II), Thornton R. (35 mi², Cl. II), Tye (30 mi², Cl. III)


F - Close-by Creeks –Rock Creek (67 mi², Cl. III), Little Patuxent (38 mi², Cl. III), Accotink Ck (37 mi², Cl. II), Pohick Ck (21 mi², Cl. II+), Cabin John Ck (18 mi², Cl. III)


10 - River Temperatures – As the season winds down, these become of vital interest as they drop  below 50 degrees.  Most gauges do not have them, but look at Little Falls (Potomac), Cartersville (James), Friendsville & Ohiopyle (Yough), Brighton Dam (Patuxent), Chadds Ford (Brandywine), and Parkton (Upper Gunpowder Falls)



Alf Cooley  - 21 Jan 2015, 24 Feb 2018, comments & corrections, please