Can I eat the fish?
Not on list
No lake-specific listing was found in this design review; statewide general guidance still applies. Check the Wisconsin DNR advice for Lake Mendota before eating fish.
Lake Mendota Water Quality
Public record · Dane County, WI
Most recent update · Sample:
Advisories & Listings
What state and federal agencies have on record for Lake Mendota.
Sample summaries for design review; these agency findings are not verified.
Are there swimming advisories?
On list · Current
Gov. Nelson State Park Beach is proposed for an E. coli listing — a public record exists; no bacteria value is shown.
Source: Wisconsin DNR Beach Health
Has a harmful algal bloom been reported?
On list · Current
Public record 2023
Is the lake on the state's impaired waters list?
On list · Current
Total phosphorus — listed 2012 for recreation use; high phosphorus and excess algal growth. TMDL approved 2011.
Are invasive species recorded?
On list · Current
Wisconsin DNR records include verified zebra mussel, spiny waterflea, Chinese mystery snail and rusty crayfish populations. Inventory records do not describe current abundance.
Source links remain available when a lake is not listed or its status is not on public record. A source link does not establish a lake-specific listing. Lakes can be added to or removed from agency lists between Lake Atlas updates. Lake Atlas is updated quarterly, not daily. Always check with the issuing agency for current advisories before you swim or eat fish.
Something missing or not accurate? Contact Lake Pulse.
Lake Profile
Public facts about Lake Mendota.
- Name (and other names)
Lake Mendota
Sample · Source: Wisconsin DNR- State
Wisconsin
Sample · Source: Wisconsin DNR- County
Dane
Sample · Source: Wisconsin DNR- Nearest community
Madison
Sample · Source: Wisconsin DNR- Latitude / longitude
43.1, -89.4
Sample · Source: Wisconsin DNR- Surface area (acres)
9,781 acres
Sample · Source: Wisconsin DNR- Maximum depth (ft)
83 ft
Sample · Source: Wisconsin DNR- Mean depth (ft)
42 ft
Sample · Source: Wisconsin DNR- Shoreline length (mi)
- Not on public record
- Elevation (ft)
- Not on public record
- Lake type
Natural lake
Sample · Source: Wisconsin DNR- State waterbody ID
- Not on public record
- HUC-8 watershed
- Not on public record
- HUC-12 subwatershed
- Not on public record
- Major river basin
Yahara River
Sample · Source: Wisconsin DNR- EPA Level III ecoregion
- Not on public record
- Public access
- Not on public record
Something missing or not accurate? Contact Lake Pulse.
Water Quality Record
The most recent public value for each key measure, with its date and source.
Sample values shown for design review — each is a placeholder with a placeholder 2023 date, pending verified pulls from the sources below.
| Parameter | Most recent value | Unit | Date | Source |
|---|---|---|---|---|
| Secchi depth | 5.8 | ft | 2023-08-15 | Wisconsin DNR (sample value) |
| Total phosphorus | 24 | µg/L | 2023-07-11 | EPA Water Quality Portal (sample value) |
| Chlorophyll-a | 18 | µg/L | 2023-07-11 | Wisconsin DNR (sample value) |
| Dissolved oxygen | Not on public record | |||
Values come from public agency, university and federal monitoring and reflect conditions on the date sampled. Older values are shown with their dates. This is not an inspection or disclosure, and Lake Pulse does not verify third-party data.
Something missing or not accurate? Contact Lake Pulse.
About Lake Mendota
The lake
Lake Mendota is a lake in Dane County, Wisconsin, at the top of the Yahara chain. Its outlet flows via the Yahara River into Lake Monona.
Source: Wikipedia, CC BY-SA
The land
Lake Mendota lies within the homelands of the Ho-Chunk Nation; the Ho-Chunk name for the Madison area is Teejop (“four lakes”).
[To be written: the Ho-Chunk name for Lake Mendota and the lake’s history.]
[To be written: early settlement and the history of the Yahara River dam and locks.]
Sources: Ho-Chunk Nation
Learn more
Something missing or not accurate? Contact Lake Pulse.
About Lake Atlas
Lake Atlas is the public record for thousands of lakes in the lower 48, gathering water quality data, advisories and lake facts from state agencies, universities and federal sources into one open page per lake. It's built for anyone who needs to know a lake before they act: residents and lake associations, buyers and real estate agents, anglers and swimmers, consultants and lake managers, and the agencies whose data it credits. If you live on or near this lake and it's the one you care about most, join this lake's Lake Pulse community for the data, testing and insights on its lake health and safety that aren't available in Atlas.
About this data
Wisconsin DNR, U.S. EPA, USGS and other public agencies already collect and publish data on Lake Mendota. Lake Atlas brings that public data together in one place so it's easier for residents, businesses, government and visitors to find, with links back to each source. All data shown comes from public sources: state agencies gather and share it, and Lake Atlas aggregates it. We're grateful to the agencies and volunteers who gather it.
Sources & methods
- Wisconsin DNR Lakes & Surface Water Data pulled 2026-09-30
- Wisconsin DNR Beach Health pulled 2026-09-30
- Wisconsin DNR Fish Consumption Advisories pulled 2026-09-30
- Wisconsin DNR Harmful Algal Blooms pulled 2026-09-30
- Wisconsin DNR Impaired Waters (303(d) list) pulled 2026-09-30
- U.S. EPA ATTAINS pulled 2026-09-30
- Water Quality Portal (USGS/EPA) pulled 2026-09-30
- Wikipedia (CC BY-SA) pulled 2026-09-30
Are we missing data on Lake Mendota?
Agencies, associations and residents: if you know a public source we haven't included, tell us.
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