01589238 - Gywnns Falls Tributary at McDonogh, Md.

Location - Lat. 39° 24 ' 01", long. 76° 46' 14", Baltimore County, Hydrologic Unit 02060003, on left bank 650 ft upstream of confluence with Gwynns Falls, on grounds of McDonogh School, 0.7 mile northwest of McDonogh, 0.8 mile southwest of Garrison, 1.4 miles southeast of Owings Mills, and 650 ft upstream from mouth.

Gaging station may be reached from intersection of I-695 and MD-140 (Reisterstown Road) as follows:

Parking, at top of watershed

From I-695 westbound, take exit 20 for MD-140 (Reisterstown Road). The exit ramp splits at the intersection with Reisterstown Road. Bear right at the split onto Reisterstown Road northbound. Follow Reisterstown Road for approximately 1.1 miles through 4 traffic lights. Turn left at the 5th traffic light, which is McDonogh Road. Follow McDonogh Road for approximately 1.3 miles to Barn Farm Road. Barn Farm Road is approximately 0.3 mile past the railroad overpass and 0.25 mile past the bridge over Gwynns Falls. Turn right onto Barn Farm Road and follow 0.33 mile to bend in road. Just beyond the bend in the road is a small unmarked road on the right that leads to the McDonogh soccer/lacrosse fields on the left and a cropped field on the right. The ADC map refers to this road as Barn Hall Road, but it is currently unmarked. Turn right and follow this road approximately 0.3 mile to a small grass path on the right side of the road. If weather conditions are dry, follow this grass path around the perimeter of the soybean field approximately 0.4 mile to gage on left. If the ground is saturated or weather conditions are wet, park on the shoulder of the paved road and walk along the grass path to the gage. See map for route to gage.

NOTE: Before going to station, send e-mail to Martin Schmidt (mschmidt@mcdonogh.org) and Rob Smoot (rsmoot@mcdonogh.org) informing them of who will be on the school grounds and when. Contact person for McDonogh security is Gary Godfrey (410-581-4792).

Establishment - November 30, 1999.

Drainage Area - 0.033 square mile (21.08 acres), measured on USGS topographic map.

Datum of Gage - 472 feet above National Geodetic Vertical Datum of 1929 (NGVD), from Rockwell Global Positioning System unit.

Intake and static tube

Gage - Steel shelter mounted on a 3" diameter, schedule 80, galvanized riser pipe. 3" pipe is connected to a 6-foot length of 2" diameter, schedule 80 galvanized pipe by a 3" to 2" reducing tee. The 2" pipe extends into the stream from under the left bank. A PVC static tube is attached at the end of the 2" pipe.

Pertinent elevations:	Gage Height (feet)
Crest of weir plate	0.59
Top of instrument shelf	4.60

Equipment shelf

Equipment - Sutron 8400 electronic stage recorder (15 minute scan interval) with stage kit.

Staff gage

Outside gage is a vertical enameled staff plate (0.00--3.34 ft) attached to a 6" x 6" pressure-treated lumber backing, anchored into base of left streambank.

A standard USGS crest-stage gage is attached to the upstream end of the 6"x 6" outside gage backing.

Pertinent elevations:	Gage Height (feet)
CSG (base cap)	1.48
CSG (length of stick)	3.97
CSG (top lip of pipe)	5.45
Top of OG	3.34
Top of OG backing	4.28
Maximum recordable stage	3.26

History

1. No other gages previously operated on this stream.

Vertical Controls

[BM = Bench Mark; RM = Reference Mark; RP = Reference Point]
RM-1 (1999, Basic)	Top of 1/2" rebar post set in concrete on left overbank, 9 ft downstream of weir and 22 ft landward of left streambank. Elevation 4.965 ft, gage datum.
RP-1 (1999)	Upstream landward corner of instrument shelf (marked in black with permanent marker). Elevation 4.596 ft., gage datum.
RP-2 (1999)	Top of 1/2" galvanized lag bolt set in base of streamward side of 36" diameter tree, 11 ft. downstream of weir and 5 ft. landward of left streambank. Elevation 4.049 ft., gage datum.
RP-3 (1999)	Top of 1/2" galvanized lag bolt set in base of streamward side of 13" diameter tree, 14 ft. downstream of weir and 16 ft. landward of left streambank. Elevation 5.776 ft., gage datum.
RP-4 (1999)	Top of 1/2" galvanized lag bolt set in base of 28" diameter tree at top of right streambank, 31 ft. upstream of weir. Elevation 5.727 ft., gage datum.

Last levels run on December 3, 1999.

Looking upstream from gage Looking downstream

Channel - The main channel is approximately 3 ft. wide. The channel is straight for approximately 30 ft upstream of the gage and then bends to the left. The channel is fairly straight for approximately 60 ft downstream of the gage and then bends to the right. The left bank will overtop at a gage height of approximately 1.5 ft. The right bank is approximately 5-6 ft. high along the gage reach. The channel is composed mainly of sand, silt, and some small gravel.

Control

Control - Control is a 7 ft x 2 ft, 3/8 inch thick aluminum weir plate with a 2 ft by 0.5 ft V-notch in the center. Crest of weir becomes control above gage height of 0.59 ft.

Wading measurement

Discharge Measurements - Wading measurements can be made at low flows by improving the cross section below the gage.

Floods -

Point of Zero Flow - 0.09 ft. (determined by levels on December 3, 1999).

Winter Records - Control pool may freeze during periods of extended cold weather.

Regulation - None.

Diversion - None.

Accuracy - Good to fair records should be obtained.

Cooperation - Baltimore Ecosystem Study, Long-Term Ecological Research; University of Maryland, Baltimore County.

Photographs - See station files.