The Little Seneca Creek Watershed

The Little Seneca Creek watershed is a large subbasin of the Great Seneca watershed and drains a significant portion of the western part of the County. The stream system originates slightly south of Damascus and drains areas of Clarksburg, Germantown, and Boyds before flowing into Great Seneca Creek just above Route 28 at Dawsonville. Little Seneca Lake, located near Boyds, is a large regional impoundment that serves as an emergency water supply source. This lake is the focal point of the Black Hill Regional Park and is known regionally as a prime location to view wintering waterfowl. It has been stocked with tiger muskie, largemouth bass, bluegill and channel catfish. Little Seneca Creek upstream of the lake is designated recreational trout waters by the state (Use IV-P) due to temperature and dissolved oxygen standards that make it suitable for an adult trout put-and-take population. Downstream of the Little Seneca Lake dam, cold-water discharges from the deeper part of the lake water column enable a natural trout waters designation (Use III-P) to the confluence with Bucklodge Branch. Rainbow and brown trout are found in this section, as well as a diverse cold-water community. Beaver have impounded large areas of Little Seneca below the lake, and massive beaver dams 5 to 6 feet high can be found.

Portions of the Upper Little Seneca Creek and Ten Mile Creek watersheds have been shaped by geological forces unique to this part of the County. A fracture fault line runs through these and the adjacent Little Bennett watersheds. These fault lines have influenced the channel morphology dramatically. The Ten Mile Creek watershed has an incredibly diverse and sensitive benthic macroinvertebrate community. Many different stoneflies and mayflies can be found in this high-quality stream. During warm winter days in late February, winter stoneflies emerge in large numbers and can be seen flying against the snow.

The Little Seneca watershed has a very mixed character of land uses, including rural areas around Boyds and the west side of Clarksburg, and higher density land uses in Germantown proper. Located along I-270, both Clarksburg and Germantown are "corridor communities" in the County's General Plan, and they contain existing and planned development in support of the County's housing and job needs. Southwest of Germantown, land uses in the watershed are typical of the agricultural reserve, with a mixture of farms and large-lot residential areas, interspersed with commercial uses at several crossroads.

Extensive planning efforts have occurred as part of the Germantown Master Plan and Clarksburg Master Plan to protect stream quality in Little Seneca Creek. These efforts include density limitations, stream valley park acquisition and dedication, reforestation, and designation of a part of Clarksburg as a Special Protection Area (SPA). SPA regulatory requirements include enhanced plan review, stream monitoring, and best management practice (BMP) performance monitoring for new development.

Over time, the character of the watershed will change considerably as the corridor cities develop. The upper sections of the watershed are still in good condition and should benefit greatly from the planning efforts that have occurred to protect water quality. Efforts taken now to address existing channel erosion and instability in the downstream reaches will be valuable in protecting the overall stream system from smaller cumulative impacts as the headwaters develop. This is particularly important for the tributaries in the Germantown area that discharge downstream of the lake. These tributaries have a direct effect on the portion of Little Seneca now designated as natural trout waters (Use III-P).

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1998 Conditions

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Little Seneca Creek Watershed Management Categories

Until fairly recently, much of this watershed consisted of rolling farmland. Changes from agricultural to suburban land use bring inevitable increases in impervious area. However, due to the planning efforts undertaken and improvements in environmental regulations and guidelines, these changes in the Little Seneca Creek watershed will be accompanied by stormwater management, stream buffers, and reforestation of riparian areas. Unlike in many older areas of the County that developed without stormwater management, these efforts should mitigate development impacts substantially. Existing problem areas showing instability from past land use and clearing activities need to be addressed to help avoid stream degradation as changes in hydrology occur in response to increased watershed development.

Existing Regulatory Special Protection Area: The County Council designated portions of the Upper Little Seneca Creek within the Clarksburg Planning Area as a Special Protection Area (SPA) in recognition of the special level of protection that would be needed to protect stream resources in the vicinity of the Town Center. Areas east of I-270 and portions of Ten Mile Creek west of I-270 were included in the SPA designation. Ten Mile Creek is an example of a sensitive area needing special protection where two different management approaches were combined to achieve the end result. SPA designation protects the drainage where high-density land uses were located along I-270, and low-density land use zoning was employed on the western side of Ten-Mile Creek.

Special level of protection: This category includes the areas above Seneca Lake outside the designated SPA, and the Milestone Tributary. The Milestone tributary is identified as needing special levels of protection, which have been provided through various efforts in the Germantown Master Plan and modeling, monitoring, and unique stormwater management controls designed to help ensure that the fragile Germantown bog area is not detrimentally impacted by proposed development.

Remedial level of protection: The Germantown Estates tributary and Brodsky tributary are recommended for remedial management efforts to address existing problems in these stream reaches.

Regular level of protection: The Churchill tributary is placed in this management category until further monitoring data are available to identify stream condition and refine a management approach.

Agricultural Watershed Management Areas: South of Boyds, land uses remain predominately agricultural in character, but several areas of large-lot residential uses are cropping up. Efforts to improve riparian buffers, particularly in the area below Route 117, are particularly needed, as are measures to address entrenched channel conditions. Efforts have shown that allowing a forested buffer to develop adjacent to streams is very effective in lessening the severity of channel erosion and instability problems on cultivated areas.

Watershed Restoration Areas: Two areas have been identified as needing restoration to address serious problems that have led to poor stream conditions: West Seneca Lake tributary and Unnamed tributary.

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Restoration Projects

Will be updated.

Watershed Studies

Will be updated.

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