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South Dakota: Build a month-by-month exposure map
Start with EIA: supply, demand, weather and storage price drivers. The table below links this decision to the represented gas companies in South Dakota. It does not establish service or supplier availability for every account.
Use weighted prices
For each month, multiply projected therms by that month’s assumed supply price. Add applicable fixed fees separately. An unweighted average gives a low-volume summer month the same influence as a high-volume heating month.
Separate price exposure from operating exposure
A fixed commodity component does not establish firm transportation or remove a curtailment obligation. Ask operations to review notice and response requirements independently of finance’s price scenario.
South Dakota utility application
| Gas service company | Seasonal cost and service exposure | Primary reference |
|---|---|---|
| NorthWestern Energy | Tariff qualification, contract demand and responsibility for daily gas needs | Official program / tariff |
| Montana-Dakota Utilities | Transportation qualification, balancing and any negotiated service agreement | Official program / tariff |
| MidAmerican Energy | Tariff qualification, contract demand and responsibility for daily gas needs | Official program / tariff |
| Watertown Municipal Utilities | Municipal gas service conditions and availability of the requested arrangement | Official program / tariff |
NorthWestern Energy: the program detail behind this decision
The South Dakota PUC lists distinct commercial sales and transportation schedules by gas company. NorthWestern lists Rate 87 transportation; MidAmerican lists monthly-metered transportation and transportation of customer-owned gas. These require their own qualification and agreements, rather than statewide small-business open enrollment. Sd Current Tariffs.
Apply the evidence to an account file
In the monthly budget, keep Sales gas-cost component versus transport, balancing and supplier costs visible. Obtain the service response for Tariff qualification, contract demand and responsibility for daily gas needs before assuming that a winter price arrangement also guarantees the required operating flexibility.
Worked check: an average can hide the heating load
Assume a hypothetical two-month illustration uses 3,000 therms at $1.00 and 1,000 therms at $0.60. The commodity total is $3,600 and the usage-weighted price is $0.90 per therm. The simple average price is $0.80; applying it to 4,000 therms understates the illustration by $400. No fees or delivery charges are included. This is arithmetic, not a claim about which local months or prices will be higher. Use all twelve actual delivery months for the real budget.
Turn the review into a calculation
Build a monthly weighted budget. Enter documented assumptions in matching energy units. Keep any charge outside both supply offers separate; the result does not establish eligibility or an available quote.
Read the South Dakota utility guide for the wider service-company distinctions. Convert billed gas units using the bill’s heat-content factor when moving from volume to energy.
Sources and review notes
- EIA: supply, demand, weather and storage price drivers
- South Dakota PUC natural gas tariffs
- Mdu Tariffs
- Sd Utility Directory
Reviewed October 16, 2026. Program information can change. Confirm the effective utility tariff, supplier availability and written offer before proceeding. Examples and planning tools are educational; they are not executable quotes or verified customer results.