Henry Hagg Lake
Washington County, Oregon1,157 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- Impaired · Oxygen depletion (low DO)
- #1 of 2 in the county
- Public access
- Limited data
Henry Hagg Lake in Washington County, Oregon has a water quality grade of A (Excellent). Chlorophyll-a (algae): 1.5 µg/L. Surface area: 1157 acres.
- Area
- 1,157 acres
- Type
- Oligotrophic
- Chlorophyll-a
- 1.5 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch Henry Hagg Lake’s letter
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Henry Hagg Lake is a 1,157-acre cold, clear oligotrophic lake in Washington County, Oregon. Water quality is graded A based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 1 other monitored lakes in Washington County, Henry Hagg Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2025-10-14. Grade methodology: LakeQuality methodology.
What Henry Hagg Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Big water1,157 acres
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The A is nutrients and algae, not a swimming clearance. Henry Hagg Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for oxygen depletion (low DO). Check local advisories before you swim.
Water Quality Grade: A (Excellent)
No clarity data. Chlorophyll-a 1.5 µg/L. TSI 35. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 1.5 µg/L | Good |
| Trophic State Index (TSI) | 35 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 1,157 acres |
| Public Access | Yes |
No bathymetric survey has been published for Henry Hagg Lake, so its depth is not documented here.
Recreation & Access
- Henry Hagg LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Henry Hagg Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Chlorophyll-a | ↑ Improving | -0.2 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Henry Hagg Lake is a man-made reservoir impounded by the Scoggins Dam (completed 1975), built primarily for irrigation on the Scoggins Creek; earth-type dam, 151 ft tall and 2,700 ft long.
- Surface area
- 1,157 ac
- Normal storage
- 59,910 ac-ft
- Max storage
- 60,000 ac-ft
- Drainage area
- 38.57 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
All listed purposes: Irrigation;Water Supply.
Source: USACE National Inventory of Dams, NID ID OR00685 · Operator website
EPA Impairment Status
Henry Hagg Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit OR_LK_1709001002_02_100840 · Official waterbody report
County Ranking
Ranked #1 of 2 lakes in Washington County
Nearby Lakes in Washington County
Frequently asked questions about Henry Hagg Lake
Where is Henry Hagg Lake?
- Henry Hagg Lake is a lake in Washington County, Oregon. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Henry Hagg Lake?
- Henry Hagg Lake in Washington County, Oregon has a water quality grade of A (Excellent). Chlorophyll-a (algae): 1.5 µg/L. Surface area: 1157 acres.
Is Henry Hagg Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Henry Hagg Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for oxygen depletion (low DO). Check local advisories before you swim.
Are there boat ramps on Henry Hagg Lake?
- Henry Hagg Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Henry Hagg Lake. Public access is listed as yes.
Explore Henry Hagg Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at Oregon's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Where this data comes from
7 measurements from 1 monitoring station, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Department of Environmental Quality - State of Oregon
OREGONDEQ7 samples · 2024–2025
Analytical methods
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Named boat-access points from the USGS National Boat Ramps inventory