Smithville Lake by Dam
Clay County, Missouri7,190 acresView mapDirections
This is the name Missouri DNR records for this water. It can describe one sampling location rather than the water as a whole.
Missouri DNR publishes the water-quality measurements for Smithville Lake by Dam. Here is what has been measured.
- Eutrophic
- Impaired · Algal growth
- Public access
Smithville Lake by Dam in Clay County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 37.7 µg/L. Chlorophyll-a (algae): 25.4 µg/L. Surface area: 7190 acres.
Smithville Lake by Dam is a 7,190-acre productive, nutrient-rich eutrophic lake in Clay County, Missouri. 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 4 other monitored lakes in Clay County, Smithville Lake by Dam ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-09-12. Methodology: how these readings are compared.
At about 7,200 acres, Smithville Lake by Dam is large enough that where you stay decides which shore you see most of. It has one public boat landing. If you are planning to stay, you can search lake houses and cabins around Smithville Lake by Dam on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
What Smithville Lake by Dam is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Big water7,190 acres
Swimming conditions
Readings onlyAlgae risk
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Smithville Lake by Dam is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
Whether Smithville Lake by Dam is safe to swim in today is a call for the Missouri Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Smithville Lake by Dam
These are the measurements Missouri DNR publishes for Smithville Lake by Dam, 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 3.3 ft of visibility. Phosphorus 37.7 µg/L. Chlorophyll-a 25.4 µg/L. TSI 60.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 37.7µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 25.4µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 60 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Smithville Lake by Dam
Answers come straight from the public measurements and survey records on this page.
→ Smithville Lake by Dam water level: the live USGS gauge reading
Water Temperature
Smithville Lake by Dam typically sits around 76°F at the surface in September. Summer average is about 81°F. Usually warmest in Jul (about 83°F) and coldest in Apr (about 57°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (57°F) to its warmest (83°F).
Typical surface water temperature by month, from 82 field readings (2010–2024) via the EPA Water Quality Portal. See the full Smithville Lake by Dam water temperature breakdown →
Lake Details
Surface area
7,190 acres
Public access
Yes
Listed by Missouri DNR
No bathymetric survey has been published for Smithville Lake by Dam, so its depth is not documented here.
Recreation & Access
- Little Platte ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Smithville Lake by Dam
Compare lakeside cabins, hotels, and vacation rentals near Smithville Lake by Dam in Clay County, Missouri — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Smithville Lake by Dam are listed below.
Top-rated places to stay near Smithville Lake by Dam
Prices for Oct 23–25, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip? Cabins and lodging at Smithville Lake by Dam → · more Missouri lake trips
Follow Smithville Lake by Dam’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Smithville Lake by Dam
Water Quality Trend: Improving
Based on 5 years of monitoring (2020–2024).
Water clarity
Stable4 years
Phosphorus
Stable+0.25 µg/L/yr5 years
Chlorophyll-a
Improving-0.66 µg/L/yr5 years
Reservoir Info (USACE NID)
Smithville Lake by Dam is a man-made reservoir impounded by the Smithville Dam (completed 1979), built primarily for flood risk reduction on the LITTLE PLATTE RIVER; earth-type dam, 105 ft tall and 4,000 ft long.
- Surface area
- 7,190 ac
- Normal storage
- 144,600 ac-ft
- Max storage
- 246,500 ac-ft
- Drainage area
- 213 sq mi
- Hazard class
- High
- Owner
- USACE - Kansas City District
All listed purposes: Flood Risk Reduction;Other;Fish and Wildlife Pond;Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID MO12084 · Operator website · Matched by proximity (0.52 km)
EPA Impairment Status
Smithville Lake by Dam is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life.
Source: EPA ATTAINS assessment unit MO_7077.00 · Official waterbody report
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Smithville Lake by Dam under Clean Water Act (NPDES) discharge permits, including 2 classified by the EPA as major dischargers. 2 facilities have a reported Clean Water Act violation in the past three years.
- Smithville WwtpSmithville · 2.1 mi away · NPDES MO0055204MajorRecent violation
- Kc Rocky Branch WwtpKansas City · 4.2 mi away · NPDES MO0048305MajorRecent violation
- Raptor Recycle And Transfer SmithvilleSmithville · 3.2 mi away · NPDES MONX01016
- Pcrsd South Gale WwtpSmithville · 4.9 mi away · NPDES MO0128074
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Clay County
Frequently asked questions about Smithville Lake by Dam
Where is Smithville Lake by Dam?
- Smithville Lake by Dam is in Clay County, Missouri. This is the name Missouri DNR records for this water. It can describe one sampling location rather than the water as a whole. Its water-quality measurements are published by Missouri DNR and shown on this page as reported.
What is the water quality of Smithville Lake by Dam?
- Smithville Lake by Dam in Clay County, Missouri has water-quality measurements published by Missouri DNR, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 37.7 µg/L. Chlorophyll-a (algae): 25.4 µg/L. Surface area: 7190 acres.
Is Smithville Lake by Dam safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Smithville Lake by Dam is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
What is the water temperature of Smithville Lake by Dam?
- Smithville Lake by Dam typically sits around 76°F at the surface in September, from 82 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
Are there boat ramps on Smithville Lake by Dam?
- Smithville Lake by Dam has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Little Platte Park. Public access is listed as yes.
Can I fish at Smithville Lake by Dam?
- Smithville Lake by Dam has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Missouri's fish and wildlife agency, so check its current regulations before you go.
Explore Smithville Lake by Dam across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at Missouri's top lakes, each with its readings
Missouri's cleanest lakes, ranked on agency measurements
More lakes in Missouri
Other Lakes in Missouri
Eutrophic Lakes in Missouri
Where this data comes from
83 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC83 samples · 2020–2024
Analytical methods
- Depth, Secchi disk in meters
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (1)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory