| Official Name: | Thunder Lake Township, Minnesota |
| Settlement Type: | Township |
| Pushpin Map: | Minnesota#USA |
| Pushpin Label Position: | left |
| Pushpin Map Caption: | Location within the state of Minnesota |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Minnesota |
| Subdivision Type2: | County |
| Subdivision Name2: | Cass |
| Unit Pref: | Imperial |
| Area Total Km2: | 94.4 |
| Area Land Km2: | 83.5 |
| Area Water Km2: | 10.9 |
| Area Total Sq Mi: | 36.4 |
| Area Land Sq Mi: | 32.2 |
| Area Water Sq Mi: | 4.2 |
| Population As Of: | 2000 |
| Population Total: | 262 |
| Population Density Km2: | 3.1 |
| Population Density Sq Mi: | 8.1 |
| Timezone: | Central (CST) |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Elevation M: | 407 |
| Elevation Ft: | 1335 |
| Coordinates: | 46.9444°N -93.9658°W |
| Postal Code Type: | ZIP code |
| Postal Code: | 56672 |
| Area Code: | 218 |
| Blank Name: | FIPS code |
| Blank Info: | 27-64876[1] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 0665787[2] |
Thunder Lake Township is a township in Cass County, Minnesota, United States. The population was 262 as of the 2000 census.[3] This township took its name from Thunder Lake.[4]
According to the United States Census Bureau, the township has a total area of 94.41NaN1, of which 83.51NaN1 is land and 10.9km2 (11.52%) is water.
As of the census of 2000, there were 262 people, 134 households, and 84 families residing in the township. The population density was 8.1 people per square mile (3.1/km). There were 541 housing units at an average density of 16.8/sq mi (6.5/km). The racial makeup of the township was 95.80% White, 3.44% Native American, and 0.76% from two or more races.
There were 134 households, out of which 14.9% had children under the age of 18 living with them, 55.2% were married couples living together, 5.2% had a female householder with no husband present, and 37.3% were non-families. 34.3% of all households were made up of individuals, and 14.9% had someone living alone who was 65 years of age or older. The average household size was 1.96 and the average family size was 2.38.
In the township the population was spread out, with 14.1% under the age of 18, 1.9% from 18 to 24, 16.0% from 25 to 44, 38.5% from 45 to 64, and 29.4% who were 65 years of age or older. The median age was 57 years. For every 100 females, there were 109.6 males. For every 100 females age 18 and over, there were 106.4 males.
The median income for a household in the township was $32,083, and the median income for a family was $38,750. Males had a median income of $31,563 versus $20,417 for females. The per capita income for the township was $20,111. About 5.4% of families and 8.6% of the population were below the poverty line, including 3.2% of those under the age of eighteen and 3.8% of those 65 or over.