ECWA - Water Quality Data for Ellerbe Creek

0.47” (measured at 6:30 am on April 4; gage had been emptied at 1:00 on April 3)
Data from Trinity Park, Durham Data from Trinity Park, Durham (www.wunderground.com graphs used with permission)
April 4:
April 3:

0.04” (measured at 1:00 pm on April 3)
1.09” (measured at 8:15 am on April 1)
0.33” (measured at 6:00 am on March 31)
0.26” (measured at 10:00 am on March 30)
-----
1.72” TOTAL
Data from Trinity Park, Durham (www.wunderground.com graphs used with permission)
April 1:
March 31:
March 30:

0.17” (measured at 9:00 am on Thursday March 20).
Data from Trinity Park, Durham (www.wunderground.com graphs used with permission)
March 19:
March 20:

Rain started at about 4:30 pm on Saturday March 15.
0.85" (measured at 10:00 am on Sunday March 16)
Data from Trinity Park, Durham (www.wunderground.com graphs used with permission)
March 15:

It rained on and off yesterday.
- 17-Acre Wood Crest Gauge: 5 1/2 inches Rain Gauge: a few drops (7:15 am); 0.1 inch (4:30 pm)
- Washington St. Crest Gauge: 1 3/4 inches
The difference between the two could result from localized differences in the intensity of the rain.

It rained most of the day yesterday.
- Washington St. Crest Gauge: 2 ft 6 in
- 17-Acre Wood Crest Gauge: 3 ft 6.25 in. Rain Gauge: 1.8 in / 4.5 cm
- Water level is roughly even with the base of the gauge. There is some current; I didn’t have my stopwatch, but estimate that it was taking ~27 seconds to flow 20 feet.
USGS: Peak height: 7.46 ft; peak discharge: 1,280 cfs. (4:45 pm)

Washington St. Crest Gauge (5:10 pm): 1 ft 7 in
- Water height is >1 inch lower than bottom of gauge stick; flow is very slow (unmeasurable).
17-Acre Wood Crest Gauge (5:20 pm): 2 ft 5 in (note discrepancy with measurement taken during storm). Rain Gauge: 1.35 in / 3.4 cm
- Water height is >1 inch lower than bottom of gauge stick; flow is very slow.

TIME	TOTAL PRECIP	17 Acre Height *	17 Acre Flow	17 Acre Discharge (cfs) **	Wash St Height *	Wash St Flow	Wash St Discharge (cfs) **
11:45 am					1 ft 10 in.	3.4 sec	112
12:10 pm	1.35 in / 3.3 cm	3 ft 5 in.	6.6 sec	150
12:40 pm					1 ft 7 in.	3.7 sec
1:50 pm	1.35 in / 3.4 cm	2 ft 6 in.	7.7 sec
2:05 pm					0 ft 9 in.	7.1 sec
* Height above base of crest gauge yardstick + 6” at 17-Acre Wood; Height above base of crest gauge yardstick + 4” at Washington St. ** cubic feet per second

17-Acre Wood Discharge in cfs = (3.4’x17’)(20’)(.85)/6.6 sec
(x-sectional area)(float distance)(roughness coefficient)/float time
Wash. St. Discharge in cfs = (1.8’x14’)(20’)(.8)/3.6 sec
It rained pretty hard during mid-morning. Still raining hard when I headed for the creek. Had slowed but was still raining steadily when I collected the 11:45 measurement. Rain began to tail off; pretty much ended by 12:40 measurement. Some drizzle / very light rain by the time I left after 2:05 measurement, but didn’t last long.
I used short lengths of thick sticks as my floaters. It was tricky to throw them in the fastest part of the flow, so I made many measurements (8 or so per effort). The shortest times reflected measurement errors (too slow hitting the button on the stop watch at the start, for instance), so I counted the fastest time I was able to get repeats of and felt confident about.
USGS Monitor, near Gorman: Peak height, discharge recorded at 2:15 pm. Rise began at ~11:15 am; tailed off until ~midnight. Peak height was 5.01 ft; peak discharge was 679 cfs.

Emptied 1 drop of water from rain gauge.
Crest gauge reading from 17-Acre Wood site: very clear line (moisture + cork) at 7 ¼ inches. A sparse scattering of cork without moisture up to 9.5 inches; I don’t know if this means anything or not (experience will tell). It is unlikely that the little bit of rain on Dec. 23 caused either; the 7 ¼ inch reading is almost certainly from the rainfall event about 1 week previous.

Crest gauge reading from Washington St. site: 6 ¾ inches (from rainfall event about 1 week previous). (I couldn’t remove the Cap from the 17-Acre Wood gauge.)
It rained for ½-1 hour after noon. I arrived at the Washington St. site at 1:00; it had just stopped raining. The stream height was ~1 inch below the bottom of the crest gauge yardstick. Flow was very slow; I tried 4 times to float an apple, but it got hung up on rocks or in shallow areas each time. If it had made it through, the time would have been more than 4 minutes.
Rain gauge installed at 17-Acre Wood (at 2:15 p.m., after rain ended). The stream level was ~1 inch below the bottom of the crest gauge yardstick.