Indiana Geothermal Heat Pump Guide 2026

Indiana doesn't usually lead geothermal conversations. Flat, agricultural, historically coal-powered — it sounds like a state you'd skip. But that description contains two of the most compelling geothermal arguments in the Midwest.

That flatness? It means horizontal ground loop systems — significantly cheaper than vertical boreholes — work across virtually the entire state. And that coal grid? At 1,393 lbs of CO₂ per megawatt-hour, Indiana has the seventh-dirtiest electricity in America. A geothermal heat pump running at COP 3.5 on Indiana's grid still delivers heat at lower effective carbon intensity than a natural gas furnace — a counterintuitive finding that creates one of the strongest carbon arguments for geothermal anywhere in the country.

Then there's the northern propane belt. From Elkhart to Fort Wayne, tens of thousands of rural homes — including the largest Amish settlement in the world — heat with delivered propane at $2.50–$3.50 per gallon. Replace that with geothermal at Indiana's 11.38¢/kWh electricity rate, and you're looking at payback periods of roughly 9–11 years with horizontal loops. That was under 8 years when the 30% federal §25D credit was available; it is not available for property placed in service after December 31, 2025 (One Big Beautiful Bill Act, P.L. 119-21), and Indiana has no state credit to replace it.

This guide maps Indiana's five distinct geothermal markets with real payback math, honest gas-city analysis, verified incentive data, and the specific angles — flat-terrain cost advantage, coal-grid carbon paradox, Amish community adoption, and farm REAP grants — that make Indiana's geothermal story more interesting than its reputation suggests.

By Geothermal Insider · Last verified March 2026

Who Should (and Shouldn't) Go Geothermal in Indiana

Payback figures reflect 2026 conditions with no federal tax credit. The 30% credit under IRC §25D applied to systems placed in service through December 31, 2025 and is not available for property placed in service after that date (One Big Beautiful Bill Act, P.L. 119-21). Earlier versions of this table showed shorter paybacks because they netted out that credit — and Indiana has no state geothermal credit to substitute. USDA REAP was not repealed. Rows carried over from the credit era are noted as such.

Installation Costs by Region

Indiana's flat terrain creates a cost advantage that most neighboring states can't match. Horizontal loops are practical across 90%+ of the state, and they cost 30–40% less than vertical boreholes. Regional cost variations reflect geology, lot conditions, local contractor availability, and whether you're in a metro area or rural county.

Out-of-pocket equals gross cost in 2026: Indiana has no state geothermal credit or confirmed utility GSHP rebate, and the 30% federal §25D credit applied only to property placed in service through December 31, 2025 (One Big Beautiful Bill Act, P.L. 119-21). For reference, these same horizontal jobs netted $11,900–$21,000 under the old credit. Costs include equipment, labor, loop installation, and ductwork modifications, and are for retrofit installations; new construction adds $8,000–$12,000 incremental over standard HVAC — the full amount now, rather than the $5,600–$8,400 the credit used to bring it to. Prices as of July 2026.

Incentives and Tax Credits

Federal 30% Section 25D Credit — Expired

The federal residential clean energy credit covered 30% of the full installed cost — equipment, labor, drilling, and trenching — for systems placed in service through December 31, 2025. It is not available for property placed in service after that date (One Big Beautiful Bill Act, P.L. 119-21). The Inflation Reduction Act had scheduled 30% through 2032 with step-downs in 2033 and 2034; that schedule was repealed before it ever took effect. On a $24,000 horizontal installation, there is no longer $7,200 back against your federal tax liability. If your system was placed in service on or before December 31, 2025, the credit still applies and any unused portion still carries forward. Verified July 2026 against IRS.gov.

No Indiana State Geothermal Credit

Indiana has no state income tax credit for residential geothermal heat pumps as of July 2026. The state's CHOICE (Comprehensive Hoosier Option to Incentivize Cleaner Energy) program targets utility-scale generation rather than homeowner incentives. Indiana's renewable policy framework has historically been utility-oriented. With the federal §25D credit now expired for property placed in service after December 31, 2025, that leaves Indiana homeowners with essentially no incentive at all outside USDA REAP eligibility. Verified July 2026 against the DSIRE Indiana database.

Utility Rebates — Unconfirmed for Ground-Source

Duke Energy Indiana offers rebates for heat pump water heaters ($800) and some HVAC equipment, but no confirmed ground-source heat pump rebate appears in their published residential programs. Indiana Michigan Power (AEP), NIPSCO, and CenterPoint Energy Indiana similarly lack published geothermal-specific rebates. (unverified — contact your utility directly; programs change annually and some "high-efficiency heat pump" categories may include ground-source systems)

USDA REAP — For Agricultural and Rural Businesses

Indiana's large agricultural sector makes USDA REAP more relevant than ever — it is now the only substantial incentive available in the state. Grants cover up to 25% of installation costs (maximum $500,000) for agricultural businesses and rural small businesses. REAP was not affected by the federal 25D repeal, but the 30% residential credit it used to stack with — which took combined coverage to 55% — is not available for property placed in service after December 31, 2025, so REAP's 25% now carries the load on its own. Contact USDA Rural Development Indiana at the Indianapolis state office for current grant cycles. See Farm Operations section for detailed math.

Incentive Stacking Summary

Case Studies

Case Study 1: LaGrange County Propane Farmhouse — 9.1-Year Payback in 2026

Case Study 2: Carmel New Construction — 7.6-Year Incremental Payback in 2026

Month-by-Month Energy Profile

What geothermal savings actually look like across an Indiana year, using a 2,400 sq ft home in LaGrange County replacing propane with a horizontal ground-source system.

Based on 6,200 HDD, 1,100 CDD. Propane at $2.85/gallon, electricity at 11.38¢/kWh. Geothermal COP 3.5 heating, EER 17 cooling. Desuperheater savings (~$45/month average) included in geo cost offset but not broken out separately.

Northern Indiana: The Propane Belt

Northern Indiana — roughly the counties from Fort Wayne and Elkhart westward through LaGrange, Kosciusko, Steuben, Noble, and DeKalb — is home to the largest Amish settlement in the world. Tens of thousands of rural homes in this corridor heat with propane, delivered by tanker truck on routes that extend deep into unmarked township roads.

The Amish community's practical, long-term approach to property stewardship has made them a significant geothermal market. The economics align with their values — geothermal has low operating costs, high durability (25+ year lifespan), and zero combustion to maintain. Several IGSHPA-certified contractors in northern Indiana and nearby Ohio have noted growing geothermal adoption in the Elkhart/LaGrange/Noble County communities over the past decade.

The propane-to-geothermal economics in this region are among the strongest in the Midwest:

• Annual propane cost: 1,100–1,400 gallons × $2.50–$3.25/gallon = $2,750–$4,550/year
• Annual geothermal cost: $650–$950/year at 11.38¢/kWh (heating + cooling combined)
• Annual savings: $1,800–$3,600
• Horizontal loop 2026 out-of-pocket: $18,000–$24,000 — the full gross cost, since the 30% federal §25D credit is not available for property placed in service after December 31, 2025 and Indiana has no state credit (it netted $12,600–$16,800 through 2025)
• Payback: 5–13 years depending on propane price and system size (it was 4–9 years when the federal credit applied)

Northern Indiana's proximity to the Chicago and Michigan markets means there's a reasonable contractor base serving this corridor from multiple directions. NIPSCO's service territory in northwest Indiana extends into the South Bend metro, where a mix of urban gas-heated homes and rural propane properties creates a bifurcated market — propane properties with compelling economics, gas properties with marginal ones.

Indiana's Flat Terrain Advantage

This bears emphasis because it's genuinely significant: Indiana is one of the flattest states in the country. Almost the entire state was glaciated during the last ice age, leaving behind uniformly flat terrain covered by deep deposits of glacial till — clay and silt with embedded gravel and stones, consistent from surface to depth.

For geothermal installation, this means horizontal trench systems are practical virtually everywhere in Indiana outside the small unglaciated karst corner in the southeast. The cost difference is substantial:

Out-of-pocket equals gross cost. The 30% federal §25D credit applied only to property placed in service through December 31, 2025 and is not available after that date (One Big Beautiful Bill Act, P.L. 119-21), and Indiana has no state geothermal credit to substitute. For reference, these same systems netted $6,300–$25,200 under the old credit.

On a 3-ton residential system, choosing horizontal over vertical saves $6,000–$12,000 — a meaningful difference that can shift payback by several years, and one that matters more now that no tax credit is available to blunt the cost.

The glacial till also has reliable thermal conductivity (~1.3–1.6 W/m·K), consistent soil temperatures at loop depth, and predictable excavation conditions. No surprise ledge rock, no inconsistent soil layers, no need to reroute a trench mid-dig.

Horizontal loops require sufficient yard area — roughly 400–600 square feet per ton with straight trenches, or less with slinky configurations. Urban and close-in suburban lots in Indianapolis, Fort Wayne, or Evansville may not have the space. Rural properties, farm acreage, and suburban homes with larger lots (0.5+ acres) are prime horizontal candidates. When space is limited, vertical boreholes remain the reliable alternative.

Indianapolis and Urban Markets

Most of Indianapolis runs on natural gas — CenterPoint Energy Indiana (formerly Vectren) and Citizens Energy Group serve the metro. Gas prices in Indiana have historically been moderate to low, partly supported by proximity to Appalachian production and Midwest pipeline infrastructure.

For existing gas-heated homes in Indianapolis, Fort Wayne, and South Bend, the energy-cost case for switching to geothermal is honest but not dramatic:

Total annual savings for most urban Indiana gas homes: $400–$900/year. Against a 2026 out-of-pocket installation cost of $30,000–$45,000 (vertical, typical for suburban lots — the full gross, since the federal §25D credit is not available for property placed in service after December 31, 2025 and Indiana has no state credit), payback runs 33 years to well over 100. The 23–35 year figure we published previously assumed that credit. Either way this is longer than the equipment's life, and we won't pretend otherwise.

The situations where urban Indiana geothermal makes strong financial sense:

• New construction: Specifying geothermal at build time adds $8,000–$12,000 over standard HVAC — the full amount now, rather than the $5,600–$8,400 the federal credit used to bring it to. Incremental payback: roughly 6–9 years, up from the 4–6 published under the credit. Indianapolis suburbs like Carmel, Fishers, Zionsville, and Noblesville are high-growth markets where geothermal still makes sense as a builder specification. See Case Study 2 for detailed math.
• System replacement at end of life: When a 20-year-old furnace and AC die simultaneously, you're choosing between standard replacement ($8,000–$15,000) and geothermal ($28,000–$42,000 gross). With no federal credit, the incremental cost is now the full $20,000–$27,000 rather than the $14,000–$19,000 net it used to be — a harder case, though it may still justify itself over a 25-year system life in northern Indiana.
• Environmental motivation: Indiana's coal grid argument (see carbon section) creates a compelling case independent of energy cost payback. Geothermal installed today gets cleaner as coal plants retire.

The Coal Grid Carbon Paradox

Indiana is one of the few states where the carbon argument for geothermal is actually stronger than the energy-cost argument.

Indiana's grid produces approximately 1,393 lbs of CO₂ per megawatt-hour — the seventh-highest carbon intensity in the U.S. (EIA 2024). That's primarily coal-fired generation. When you run an electric appliance in Indiana, the electrons behind it are mostly coal electrons.

A geothermal heat pump at COP 3.5 uses 1 kWh of electricity to deliver 3.5 kWh of heating. The carbon cost of that 1 kWh at Indiana's grid intensity: ~0.63 lbs of CO₂. But you got 3.5 kWh of heat, so the effective carbon intensity of geothermal heating is 0.63 ÷ 3.5 = roughly 0.18 lbs CO₂ per kWh of delivered heat.

A high-efficiency natural gas furnace (98% AFUE) produces about 0.116 lbs of CO₂ per kWh of delivered heat from direct combustion. So geothermal on Indiana's coal grid delivers heat at roughly 50% more carbon intensity than a gas furnace in heating mode alone.

But here's where the paradox resolves:

1. Cooling matters. Geothermal replaces coal-fired central AC with dramatically more efficient ground-source cooling (EER 17–25 vs. SEER 14–16 for standard AC). In Indiana's humid summers (1,000–1,200 CDD), cooling efficiency improvements cut carbon significantly.
2. The grid is changing. Indiana's major utilities have announced significant coal plant retirements through 2035. Every coal plant that retires improves the carbon math for every geothermal system already in the ground. A system installed in 2026 that runs on 40–60% cleaner electricity by 2035 will have dramatically better lifetime carbon performance than its install-year number suggests.
3. Infrastructure lock-in. Installing a gas furnace in 2026 locks in a fossil fuel appliance for 20+ years. Installing geothermal locks in electric-efficiency infrastructure that improves with the grid. The investment thesis is about trajectory, not snapshot.

For homeowners focused on long-term carbon impact, Indiana's coal transition makes geothermal a high-value investment — you're locking in equipment that improves with the grid, rather than locking in equipment that doesn't.

Open-Loop System Assessment

Open-loop systems use groundwater directly as the heat exchange medium — typically more efficient than closed-loop when water quality and quantity are adequate. Indiana's open-loop viability varies significantly by region.

Open-loop permitting: Indiana Department of Natural Resources (IDNR) well construction permit required. Indiana Department of Environmental Management (IDEM) may require discharge permits depending on volume and receiving body. Re-injection wells require separate IDNR permits. Typical flow requirement: 3 GPM per ton for pump-and-dump, 1.5 GPM per ton with re-injection.

Farm Operations and USDA REAP

Indiana's corn and soybean production ranks it among the top five agricultural states in the country. The USDA REAP program's 25% grant is relevant across a large share of Indiana's geography — most of the state outside the Indianapolis metro qualifies as "rural" under USDA definitions.

For an Indiana farm installing geothermal in a barn, grain facility, hog operation, or the main farmhouse as part of a qualifying agricultural business:

Under the pre-2026 rules this same stack netted to $12,600 (55% covered) with a 5.7-year payback, because the 30% federal §25D credit applied on top of REAP. REAP itself was not repealed — only the federal 25D component came out, and Indiana has no state credit to replace it. Note also that a genuinely commercial farm building (barn, grain facility, hog operation) may instead fall under the separate Section 48 business energy credit, which was not repealed; a farmhouse cannot. Which provision covers which structure is a fact-specific tax question — consult a professional.

Indiana's abundant farm ponds add another dimension. A closed pond loop — coiled HDPE sunk to the bottom of an existing farm pond — costs $3,000–$5,000 per ton installed, significantly below either horizontal or vertical costs. Farm operations with ponds deep enough for loop placement (8+ feet at maximum depth, year-round) can combine REAP grants with pond loop savings for some of the best total geothermal economics still available in the Midwest — the federal residential credit is no longer part of that stack.

REAP application tips for Indiana farmers:

• Contact USDA Rural Development Indiana (Indianapolis state office: 317-290-3100) for current funding cycle dates
• Applications require an energy audit or assessment — budget $500–$1,500 for this
• Competitive grants favor projects with shorter payback periods — propane replacement scores well
• REAP no longer stacks with a federal residential credit — IRC §25D is not available for property placed in service after December 31, 2025. A qualifying commercial farm structure may still use the separate Section 48 business credit, which was not repealed
• Farm operations replacing propane with horizontal or pond loops have the strongest applications

Solar + Geothermal Stacking Strategy

Indiana's solar resource is moderate — 4.2–4.6 peak sun hours per day — but the combination of solar panels with geothermal creates a multiplier effect that's worth understanding.

A geothermal heat pump converts your home's entire energy load (heating, cooling, and partial hot water) to electricity. Solar panels then offset that electricity cost. The combination produces near-zero energy bills year-round:

• Geothermal operating cost (2,400 sq ft home): ~$1,200–$1,600/year in electricity
• Solar to offset geothermal: ~6–8 kW system, $14,000–$20,000 out of pocket in 2026. Residential solar also ran through IRC §25D and also lost the 30% credit for property placed in service after December 31, 2025 — the $9,800–$14,000 net we published previously no longer applies
• Combined net energy cost: Near zero (net metering varies by utility — check your provider)

Indiana's net metering policies have been controversial. As of 2022, new customers receive 1:1 credit through 2032, after which the rate may shift to a lower avoided-cost rate. This affects the solar-only calculation but less so for solar-plus-geo owners, where most generation is consumed on-site by the heat pump rather than exported to the grid.

Both systems ran through IRC §25D, and both qualified at 30% only for property placed in service through December 31, 2025. Neither qualifies after that date (One Big Beautiful Bill Act, P.L. 119-21), so there is no combined credit and no Form 5695 to file for a 2026 install. The engineering case for pairing them is unchanged — if you're building new or making a major energy overhaul, designing both systems simultaneously still lets the contractor optimize sizing and placement — but budget both at full price.

Vacation Rental and Tourism Properties

Indiana's tourism market creates a specific geothermal opportunity that standard residential math doesn't capture.

Brown County: Nashville, Indiana and surrounding Brown County draw 3+ million visitors annually. Cabin rentals in the Brown County hills command $150–$300/night, often with year-round occupancy during leaf season (October), holiday weekends, and summer. These cabins typically heat with propane — standard for rural Brown County. A geothermal system eliminates the propane delivery coordination headache for a rental property while cutting operating costs.

Indiana Dunes: Michigan City, Porter, and Chesterton vacation rentals near Indiana Dunes National Park see strong summer demand and growing winter weekend traffic. Properties converting from propane or electric heat to geothermal can market the sustainability angle — increasingly valued by the Chicago-area renters who dominate this market.

The rental multiplier: A vacation rental running 200–280 nights per year (typical for popular Indiana properties) uses more heating and cooling energy than an owner-occupied home. More energy use = larger savings from geothermal's efficiency. The payback calculation improves proportionally.

Marketing advantage: "Heated and cooled by geothermal — no fossil fuels" is a premium listing feature on Airbnb, VRBO, and Hipcamp. Properties in Brown County and Indiana Dunes can charge $10–$25/night more with a sustainability positioning that geothermal supports credibly.

Geology and Ground Conditions

Central and Northern Indiana — Glacial Till

The dominant geology across ~90% of Indiana. Deep clay-silt glacial till from the Wisconsin ice sheet. Consistent thermal conductivity (~1.3–1.6 W/m·K). Horizontal loops practical and cost-effective. Vertical boreholes also straightforward — no significant hard rock until deeper depths. Water table varies but is generally 15–40 feet below grade. Ground temperature: 53–55°F at loop depth.

Northwest Indiana — Lake Plain

The Gary/Hammond/Michigan City corridor sits on lacustrine (lake bed) deposits — fine silt and sand from ancient glacial Lake Chicago. Thermal conductivity slightly lower than glacial till (~1.1–1.4 W/m·K). Horizontal loops work but may need slightly larger loop fields. Shallow water table near Lake Michigan can complicate horizontal excavation — closed-loop vertical may be preferred in some locations.

Southwest Indiana — Wabash Lowland

The Terre Haute to Evansville corridor sits on thinner glacial deposits over sedimentary bedrock. Thermal conductivity adequate but less predictable than the deep till of central Indiana. Horizontal loops work in most locations but verify depth to bedrock. Coal seams present at depth in some areas — consult your driller about site conditions.

Southeast Indiana — Karst Corner

Crawford, Harrison, Washington, and parts of Jackson, Lawrence, and Orange counties sit on unglaciated limestone bedrock with karst features — sinkholes, underground streams, caves. This is geologically similar to south-central Kentucky and parts of Tennessee. In this area: closed-loop systems only. Open-loop not advised due to unpredictable fracture connectivity. Vertical boreholes work but require karst-experienced drillers who can navigate void spaces and grout properly. Ask your contractor about karst risk assessment before finalizing design.

Ground Temperatures

Indiana: 52–55°F statewide at loop depth, warmer in the south. Fully within the operational range for geothermal heat pumps. COP of 3.2–4.0 in heating mode at these entering water temperatures, depending on the unit and loop design.

Permitting in Indiana

Horizontal closed-loop: Standard local mechanical and building permits. No state water well permit required for closed horizontal trench systems. County zoning rules may apply for agricultural land disturbance — verify with your township before excavating.

Vertical closed-loop: Indiana Department of Natural Resources (IDNR) oversees water well construction under 312 IAC 13. A licensed well driller is required for vertical boreholes. Grouting requirements apply — your contractor should be familiar with Indiana's well construction standards. Borehole log filed with IDNR after completion.

Open-loop systems: IDNR well permit required for groundwater withdrawal. Minimum flow rates: 3 GPM per ton (pump-and-dump) or 1.5 GPM per ton (re-injection). Discharge permits from IDEM (Indiana Department of Environmental Management) may apply depending on volume and receiving body. Re-injection wells require separate IDNR construction permits.

Southeast Indiana karst: Additional scrutiny for any drilling or water withdrawal in karst areas. Consult with IDEM and your contractor about site-specific requirements in Crawford, Harrison, Washington, and Orange counties.

Finding a contractor: Search the IGSHPA contractor finder for Indiana. The state has a growing base of certified geothermal contractors, concentrated in the Indianapolis metro and northern Indiana near the Ohio/Michigan markets. For northern Indiana, also check contractors licensed in Ohio (many serve both states across the border). For southeast Indiana karst, look for drillers with Kentucky/Tennessee karst experience.

The Federal Tax Credit: What Changed for 2026

The 30% federal credit under IRC §25D applied to systems placed in service through December 31, 2025. It is not available for property placed in service after that date (One Big Beautiful Bill Act, P.L. 119-21). The Inflation Reduction Act had set 30% through 2032 with step-downs in 2033 and 2034; that schedule was repealed before it took effect.

Indiana has no state geothermal incentive, so for a 2026 residential install there is no credit at all — federal or state — outside USDA REAP eligibility. Budget the full gross cost.

The steps below apply only if your system was placed in service on or before December 31, 2025 and you are still filing or amending for that year:

1. Step 1: Confirm your placed-in-service date. Anything after December 31, 2025 does not qualify — skip to Step 6. For a qualifying pre-2026 install, ground-source heat pumps meeting Energy Star requirements qualify. Your installer should confirm the equipment meets Section 25D criteria. Keep all invoices, contracts, and the Manufacturer's Certification Statement.
2. Step 2: Gather documentation. You'll need: (a) Total installed cost including equipment, labor, drilling/trenching, and ductwork modifications; (b) Installer's invoice with line-item breakdown; (c) Manufacturer's Certification Statement (Form 8908-E equivalent — request from your installer); (d) Proof of placement in service (completion date).
3. Step 3: Complete IRS Form 5695. Download Form 5695 (Residential Energy Credits) from irs.gov. Enter total qualified costs in Part I, Line 14a (Geothermal heat pump property). Calculate 30% credit on Line 14b.
4. Step 4: Transfer to Form 1040. The credit from Form 5695 flows to Schedule 3, Line 5, then to Form 1040, Line 20. This reduces your tax liability dollar-for-dollar.
5. Step 5: Handle carryforward if needed. If your federal tax liability is less than the credit amount, the excess carries forward to future tax years. There's no expiration on the carryforward — claim the remainder on next year's Form 5695.
6. Step 6: Keep records. Retain all documentation for at least 3 years after claiming the credit (IRS standard audit window). Store invoices, the Manufacturer's Certification, Form 5695, and photos of the installation.
7. Step 7: File with your return — or, for a 2026 install, budget the full gross cost. For a pre-2026 system, attach Form 5695 to your federal return; the credit is nonrefundable, reducing what you owe but not generating a refund below zero. For anything placed in service after December 31, 2025, Form 5695 no longer applies to geothermal and there is no state credit to fall back on — the quoted price is the price.

Tip: Through 2025, if you also installed solar panels, both systems were claimed on the same Form 5695, each getting 30% independently with no combined cap. Neither qualifies for property placed in service after December 31, 2025.

Indiana vs. Neighboring States

Indiana's flat-terrain advantage is real. Horizontal loop installation costs in Indiana are among the lowest in the Midwest simply because the terrain cooperates everywhere. Ohio shares this advantage in the northwest but has Appalachian hills in the southeast. Illinois is similarly flat but has higher electricity rates. Michigan has more variable terrain and higher electricity costs. Kentucky is mostly hilly, requiring more expensive vertical installations statewide.

Video Resources

Frequently Asked Questions

Sources

• EIA Indiana Electricity Profile 2024 — U.S. Energy Information Administration · Verified March 2026
• DSIRE Indiana Incentive Programs — Database of State Incentives for Renewables & Efficiency · Verified March 2026
• IRS Residential Clean Energy Credit (Section 25D) — Internal Revenue Service · 30% GSHP credit applied to property placed in service through Dec 31, 2025; not available after that date (One Big Beautiful Bill Act, P.L. 119-21) · Verified July 2026
• USDA REAP Program — Rural Development · Verified March 2026
• Duke Energy Indiana Home Energy Improvement Programs
• IGSHPA Certified Geothermal Contractor Finder
• IDNR Water Well Drillers and Pump Installers — Indiana Department of Natural Resources
• Indiana Department of Environmental Management — Water Quality Permits
• EIA Indiana Natural Gas Prices — U.S. Energy Information Administration
• NOAA Ground Temperature Data — National Oceanic and Atmospheric Administration
• ACS Housing Fuel Type Data — U.S. Census Bureau
• Ohio Geothermal Guide — Geothermal Insider
• Illinois Geothermal Guide — Geothermal Insider
• Michigan Geothermal Guide — Geothermal Insider
• Kentucky Geothermal Guide — Geothermal Insider
• Geothermal Installation Cost Guide — Geothermal Insider
• Geothermal Payback Period Calculator — Geothermal Insider
• Geothermal vs. Propane Heating — Geothermal Insider
• Federal Geothermal Tax Credit Guide — Geothermal Insider

Figures marked (unverified) are our best reading of program documentation that we were not able to confirm independently. Rebate and incentive terms change often — confirm current amounts with the utility or program administrator before you budget against them.