Long Draught Branch Lake
Montgomery County, Maryland90 acresView mapDirections
MDE publishes the water-quality measurements for Long Draught Branch Lake. Here is what has been measured.
- Impaired · Algal growth
- Limited data
Long Draught Branch Lake in Montgomery County, Maryland has water-quality measurements published by MDE, shown here as reported. Water clarity: 8.5 ft visibility. Surface area: 90 acres.
Long Draught Branch Lake is a 90-acre lake in Montgomery County, Maryland. Overall water quality is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2017-10-23. Methodology: how these readings are compared.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Long Draught Branch Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen), sediment / turbidity. Check local advisories before you swim.
Whether Long Draught Branch Lake is safe to swim in today is a call for the Maryland Department of the Environment and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Long Draught Branch Lake
These are the measurements MDE publishes for Long Draught Branch Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 8.5 ft. TSI 46.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 8.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 46 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Long Draught Branch Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
90 acres
No bathymetric survey has been published for Long Draught Branch Lake, so its depth is not documented here.
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Fishing Long Draught Branch Lake
Water quality readings over time
3 seasons of samples on record (2014–2017). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving3 years
Reservoir Info (USACE NID)
Long Draught Branch Lake is a man-made reservoir impounded by the Seneca State Park Dam (Seneca Creek Road) (completed 1975), built primarily for recreation on the Long Draught Branch; earth-type dam, 64 ft tall and 580 ft long.
- Surface area
- 90 ac
- Normal storage
- 1,592 ac-ft
- Max storage
- 2,792 ac-ft
- Drainage area
- 2.9 sq mi
- Hazard class
- High
- Owner
- MD DNR-Public Lands, Engineering & Constr-Southern
All listed purposes: Recreation;Flood Risk Reduction.
Source: USACE National Inventory of Dams, NID ID MD00087 · Operator website · Matched by proximity (0.72 km)
EPA Impairment Status
Long Draught Branch Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Drinking water, Aquatic life.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MD-021402080857-Clopper_Lake · Official waterbody report
Nearby Lakes in Montgomery County
Frequently asked questions about Long Draught Branch Lake
Where is Long Draught Branch Lake?
- Long Draught Branch Lake is a lake in Montgomery County, Maryland. Its water-quality measurements are published by MDE and shown on this page as reported.
What is the water quality of Long Draught Branch Lake?
- Long Draught Branch Lake in Montgomery County, Maryland has water-quality measurements published by MDE, shown here as reported. Water clarity: 8.5 ft visibility. Surface area: 90 acres.
Is Long Draught Branch Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Long Draught Branch Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen), sediment / turbidity. Check local advisories before you swim.
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Where this data comes from
1,027 measurements from 4 monitoring stations, 2014–2017. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples1,027 samples · 2014–2017
Monitoring station identifiers (4)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database