Waterlands
Difficult Run
USGS · 01646000
DIFFICULT RUN
USGS · 01646000LIVE

DIFFICULT RUN NEAR GREAT FALLS, VA

RESTON, VA38.9759°N, -77.2458°W Updated 20 hr ago
FLOW RATE
47cfs
GAUGE HT
3.18ft
WATER TEMP
78°F
AIR TEMP
76°F
WIND
1mph S
FISH INDEX
75SCORE / 100
GREAT · 4 OF 5
Flow Rate Historical Avg
MEDIAN FLOW RATE · 7 DAY
47cfs 5.6% vs avg
Optimal band: 20–26 cfs
PERIOD HIGH
158cfs
PERIOD LOW
7cfs
RUNNABLE
13%
last 7 day in band

Gauge Height

3.18ft

Water Temperature

77.7°F

Water Turbidity

Precipitation History
Your History · DIFFICULT RUN NEAR GREAT FALLS, VA

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Weather Conditions
WEATHER CONDITIONS
TODAY
81°
71°
MON
87°
67°
TUE
93°
65°
WED
101°
75°
THU
93°
77°
FRI
85°
67°
SAT
86°
64°
TIME
SUN
8
NOW
9
pm
10
pm
11
pm
MON
12
am
1
am
2
am
3
am
4
am
5
am
6
am
7
am
8
am
9
am
10
am
11
am
12
pm
1
pm
2
pm
3
pm
4
pm
5
pm
6
pm
7
pm
8
pm
9
pm
10
pm
11
pm
TUE
12
am
1
am
2
am
3
am
4
am
5
am
6
am
7
am
8
am
9
am
10
am
11
am
12
pm
1
pm
2
pm
3
pm
4
pm
5
pm
6
pm
7
pm
8
pm
9
pm
10
pm
11
pm
WED
12
am
1
am
2
am
3
am
4
am
5
am
6
am
7
am
8
am
9
am
10
am
11
am
12
pm
1
pm
2
pm
3
pm
4
pm
5
pm
6
pm
7
pm
8
pm
9
pm
10
pm
11
pm
THU
12
am
1
am
2
am
3
am
4
am
5
am
6
am
7
am
8
am
9
am
10
am
11
am
12
pm
1
pm
2
pm
3
pm
4
pm
5
pm
6
pm
7
pm
8
pm
9
pm
10
pm
11
pm
FRI
12
am
1
am
2
am
3
am
4
am
5
am
6
am
7
am
8
am
9
am
10
am
11
am
12
pm
1
pm
2
pm
3
pm
TEMP
hourly forecast
77°
mild
77°
75°
73°
71°
70°
69°
69°
68°
67°
67°
68°
68°
72°
75°
78°
80°
82°
85°
86°
87°
87°
87°
87°
85°
81°
78°
75°
73°
72°
70°
69°
68°
67°
66°
65°
68°
73°
77°
81°
84°
86°
89°
91°
93°
93°
93°
93°
91°
87°
84°
82°
80°
79°
78°
77°
76°
76°
76°
75°
76°
80°
84°
87°
91°
94°
96°
98°
99°
100°
101°
101°
98°
92°
88°
87°
86°
85°
84°
83°
82°
80°
78°
77°
78°
80°
84°
87°
88°
89°
93°
92°
88°
90°
92°
90°
86°
84°
82°
80°
78°
76°
74°
73°
72°
70°
69°
68°
67°
70°
72°
75°
78°
80°
82°
83°
84°
WIND
mph · gust · dir
1mph SSW
G 11 mph
1
G11
SSW
4
G10
SSE
4
G12
SE
5
G13
SSE
2
G9
ESE
3
G6
ENE
2
G3
NE
3
NE
3
G5
ENE
2
G5
NNE
2
G6
NE
3
G7
E
4
G11
E
5
G10
SE
4
G9
SE
4
G10
SE
4
G9
SSE
5
G7
SSE
5
G6
SSE
5
G7
SSE
5
G7
SE
5
G6
SE
5
G6
SSE
5
G7
S
4
G11
S
5
G10
SSE
5
G12
S
3
G11
SSE
2
G10
SE
2
G11
SSW
2
G9
NE
1
G10
NNW
2
G11
S
0
G10
S
1
G9
NE
1
G6
N
4
G11
SW
4
G8
WSW
4
G6
WSW
5
G7
SW
5
G6
SW
5
WSW
5
G6
WSW
5
W
5
G6
W
5
G6
W
5
G7
W
3
G5
WSW
4
G6
SSW
5
G12
SW
6
G15
SW
5
G15
SW
5
G16
SW
6
G18
SW
5
G11
WSW
4
G6
W
4
G7
WNW
4
G10
WNW
5
G12
W
5
G16
W
6
G18
WNW
7
G17
WNW
8
G15
WNW
8
G13
WNW
8
G12
WNW
8
G11
NW
8
G11
NW
8
G12
WNW
6
G12
WNW
6
G12
W
6
G13
WNW
4
G7
NW
4
G8
NNW
4
G11
N
4
G7
NNW
4
G5
NW
5
G13
NW
5
G16
NW
6
G15
NW
4
G10
NW
4
G8
NNW
5
G9
NNW
3
NNW
4
G6
NNW
2
G4
NNW
4
G9
NW
7
G14
WNW
9
G16
NW
9
G16
NW
9
G16
NW
10
G16
NNW
5
G11
N
11
G17
N
12
G19
N
12
G21
NNW
11
G25
NNW
12
G27
NNW
12
G28
NNW
10
G29
NNW
9
G29
NNW
8
G28
NNW
7
G26
NNW
7
G24
NNW
7
G22
NNW
7
G20
NNW
7
G21
NNW
8
G22
NNW
8
G20
NNW
8
G17
NNW
8
G16
NNW
9
G15
NNW
9
G15
NNW
9
G14
NNW
9
G15
NNW
10
G15
NNW
9
G15
NNW
PRECIP
chance %
6%
6%
3%
1%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
1%
1%
1%
1%
1%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
1%
1%
1%
1%
1%
1%
7%
7%
7%
7%
7%
7%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
3%
3%
3%
3%
3%
3%
7%
7%
7%
7%
7%
7%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
7%
CLOUDS
cover %
95%
overcast
95%
100%
100%
81%
24%
88%
39%
19%
18%
100%
100%
76%
16%
25%
33%
16%
16%
27%
26%
35%
38%
26%
13%
41%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
5%
5%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
5%
10%
45%
85%
16%
10%
12%
62%
39%
11%
0%
46%
62%
7%
7%
47%
100%
7%
80%
24%
97%
100%
100%
100%
100%
81%
100%
22%
79%
100%
100%
100%
100%
100%
100%
90%
100%
100%
100%
100%
100%
8%
11%
10%
100%
100%
75%
14%
0%
0%
1%
0%
0%
0%
0%
0%
0%
0%
PRESSURE
hPa · trend
1012
10121013101510141012101310131010100710061007100510021003100310021003100610091009
TemperatureWind / GustsPrecipitationCloud coverPressure
Nowscroll →
FISH INDEX
75
Temperature
Warm
Wind
Calm
Pressure
Stable
Moon Phase
Average
DAYLIGHT
SUNRISE
05:53 AM
SUNSET
08:35 PM
14H 42M OF DAYLIGHT
MOON PHASE
Waning Crescent
4% illuminated

Station Location

38.9759, -77.2458
Loading map…
DATA · USGS · NOAA · NWSUPDATED 2026-07-12 00:00 UTC
Site #01646000·USGS

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