Lake Needwood
Montgomery County, Maryland74 acresView mapDirections
MDE publishes the water-quality measurements for Lake Needwood. Here is what has been measured.
- Limited data
Lake Needwood in Montgomery County, Maryland has water-quality measurements published by MDE, shown here as reported. Water clarity: 3 ft visibility. Surface area: 74 acres.
Lake Needwood is a 74-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 2020-03-09. Methodology: how these readings are compared.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Lake Needwood 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 Lake Needwood
These are the measurements MDE publishes for Lake Needwood, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 3 ft of visibility. TSI 62.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3ft | 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. | 62 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Lake Needwood
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
74 acres
No bathymetric survey has been published for Lake Needwood, so its depth is not documented here.
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Stays near Lake Needwood
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Fishing Lake Needwood
Water quality readings over time
3 seasons of samples on record (2012–2019). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving3 years
Reservoir Info (USACE NID)
Lake Needwood is a man-made reservoir impounded by the Lake Needwood (completed 1965), built primarily for recreation on the Rock Creek; earth-type dam, 65 ft tall and 426 ft long.
- Surface area
- 74 ac
- Normal storage
- 600 ac-ft
- Max storage
- 7,023 ac-ft
- Drainage area
- 12.8 sq mi
- Hazard class
- High
- Owner
- MNCPPC-Upper Rock Creek
All listed purposes: Recreation;Flood Risk Reduction.
Source: USACE National Inventory of Dams, NID ID MD00046 · Operator website
Nearby Lakes in Montgomery County
Frequently asked questions about Lake Needwood
Where is Lake Needwood?
- Lake Needwood 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 Lake Needwood?
- Lake Needwood in Montgomery County, Maryland has water-quality measurements published by MDE, shown here as reported. Water clarity: 3 ft visibility. Surface area: 74 acres.
Is Lake Needwood safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Lake Needwood across LakeQuality
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Where this data comes from
226 measurements from 4 monitoring stations, 2019–2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Submitting organization not recorded for these samples226 samples · 2019–2020
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.