01589197 - Gwynns Falls near Delight, Md.

Location - Lat. 39° 26' 35", long. 76° 47' 02", Baltimore County, Hydrologic Unit 2060003, on downstream side of bridge on Gwynnbrook Avenue, 1.2 miles east of Delight, 1.6 miles north of Owings Mills, and 1.6 miles northeast of Belltown.

Gaging station may be reached from intersection of I-795 Northbound and Owings Mills Boulevard as follows:

Parking, looking east from gage

From I-795 Northbound, take exit 4 (Owings Mills Boulevard). When exit ramp splits, stay to the right and merge onto Owings Mills Boulevard. Follow Owings Mills Boulevard 0.5 mile through intersection with MD-140 (Reisterstown Road), and another 1.7 miles to intersection with Gwynnbrook Avenue. Turn left onto Gwynnbrook Avenue. About 200 feet past the turn, pull into entrance to fenced sewage-dumping station on the right and park vehicle, just prior to crossing railroad tracks. Bridge crossing Gwynns Falls is visible just beyond the railroad tracks. Gage is located on the downstream side of the bridge on Gwynnbrook Avenue, on the opposite side of the railroad tracks from the sewage-dumping station. See map for route to gage.

Establishment - September 10, 1998.

Drainage Area - 4.23 square miles (measured on USGS topographic maps).

Datum of Gage - 534.196 above National Geodetic Vertical Datum of 1929 (NGVD), from field survey.

Intake and static tube, from left bank

Gage - Steel shelter mounted on a 3" diameter, schedule 80 galvanized riser pipe secured to downstream, streamward end of concrete bridge pier adjacent to right bank. The 3" pipe is connected to a short length of 2" diameter, schedule 80 galvanized pipe by a 3" to 2" reducing tee. A galvanized static tube is attached at the end of the 2" pipe.

Pertinent elevations:	Gage Height (feet)
Top of instrument shelf	11.61

Equipment shelf Rain gage Staff gage and crest-stage gage

Equipment - Sutron 8400 electronic stage recorder (15 minute scan interval) with stage kit. J+S RG-400 tipping bucket rain gage is mounted on top of a 6" x 6" timber fence post on the left overbank just downstream of the bridge and wired into the Sutron stage recorder (15 minute scan interval). Outside gage is a vertical enameled staff (0.00 - 6.74 ft.) attached to 2" x 10" x 6.8 ft pressure treated lumber, bolted to concrete facing on downstream end of bridge pier, adjacent to toe of left bank. A standard USGS 2" diameter crest-stage gage is attached to the downstream, landward side of the concrete bridge pier adjacent to the left bank.

Pertinent elevations:	Gage Height (feet)
CSG (base cap)	1.941
CSG (length of stick)	--
Top of OG backer board	6.846
Maximum recordable stage	--

History

1. Station 01589200, Gwynns Falls near Owings Mills, Md., was operated during 1958-75, approximately 0.25 mile downstream of the current location. No previous station has been operated in the current location.

Vertical Controls

[BM = Bench Mark; R = Reference; RM = Reference Mark; RP = Reference Point]
R-13 (1935, Basic)	National Coastal and Geodetic Survey standard disk, stamped R-13, set in top, downstream end of left abutment of railroad bridge, approximately 210 feet south of intersection of railroad tracks at Gwynnbrook Avenue. Elevation 7.519 ft., gage datum; 541.715 ft. above NGVD.
RM-1 (1998)	Chiseled square on top, downstream side of left bridge abutment. Elevation 9.938 ft., gage datum; 544.134 ft. above NGVD.
RP-1 (1998)	Painted square on corner of instrument shelf. Elevation 11.606 ft., gage datum; 545.802 ft. above NGVD.

Last levels run on September 28, 1998.

Looking upstream from gage Looking downstream

Channel - The channel bed is composed of predominantly gravel, cobbles, and sand. The channel banks are composed of silt and clay, with small amounts of sand. Channel alignment through the bridge is fairly straight. Low flows are confined to middle bridge opening, but higher flows will pass through bridge openings on the left and right overbank. The downstream channel is straight for approximately 80 feet, then bends to the left. Higher flows are confined by a railroad embankment on the left overbank. The right overbank is wooded, with gradually increasing elevations to confine higher flows.

Control

Control - Low-water control is rock riffle located approximately 40 feet downstream of the gage. Channel control at medium stages. High-water control is railroad bridge, approximately 250 feet downstream of gage.

Wading measurement Bridge measurement

Discharge Measurements - Low-water measurements can be made by wading about 10 ft. below the gage. Medium and high-stage measurements can be made from the downstream side of the highway bridge.

Floods - Flood of July 22, 1999 reached a stage of 6.81 ft., based on CSG mark. Flood of September 16, 1999 reached a stage of 5.57 ft., based on recorded data.

Point of Zero Flow - Varies due to shifting rocks in control area, but is stable during extended periods of lower flows.

Winter Records - Stage-discharge relation may be affected by ice during periods of extended cold.

Regulation - None.

Diversion - None.

Accuracy - Good records should be obtained.

Cooperation - Baltimore County Department of Environmental Protection and Resource Management.

Photographs - See station files.