Proposed North End Cell Tower:
Interactive Financial Model
Run the financial case yourself
The Board's decision to proceed with a 155-foot commercial cell tower near the dog park rests on ten specific assumptions about construction cost, carrier demand, lease rates, operating costs, and tower lifespan. This interactive calculator lets you explore those assumptions and see how the project's Net Present Value (NPV) changes when any of them moves.
Start with a preset: Three TSRA published buttons load the Board's own pessimistic, midpoint, and optimistic scenarios, calibrated to the NPV figures in TSRA's April and August 2025 financial materials. The member-researched button loads the realistic case built from industry data, public TSRA documents, and the records produced through member inquiry.
Then explore: Adjust any slider to test your own assumptions. Click the small i icon next to any input to read the detailed analysis and sources behind that assumption. As you make adjustments to the model inputs, the cash flow chart, NPV, and estimated impact on monthly dues per lot all update in real time.
What you'll find: Under the realistic scenarios identified by member research, the project NPV is negative across the vast majority of scenarios. The TSRA's case requires multiple optimistic assumptions to hold simultaneously. The two inputs with the largest swing are the discount rate (how risky the project investment is considered to be) and the useful life (how long the tower generates revenue from the initial project investment). Both are documented in detail in member analysis links.
EXPLORE SCENARIOS WITH CALCULATOR
Quick Calculator Presets
- No lease negotiator fee applied, despite now being CONTRACTUALLY OBLIGATED
- $600K base construction; excludes separately-listed site items
- Monopine design premium applied to TSRA pessimistic case only
- $100K other up-front expenses (per April 2025 Finance Committee memo)
- 4 carriers, 30-year useful life
- 7% target financial hurdle
- $22K annual operating costs
- Lease negotiator fee applied (contractually obligated)
- Construction includes excluded site items (road, generator, fence, tree removal)
- Monopine premium applied to the pessimistic case only
- Higher other up-front expenses
- Fewer carriers and shorter useful life
- Reduced lease rate per carrier
- Higher target financial hurdle
- Higher annual operating costs
Model inputs
Output: Your scenario
At these assumptions, the project would generate roughly $3.00/month of dues offset per lot over its life. This is small in absolute terms (less than 1% of current dues) and depends on every input above behaving as the Board's published case assumes.
TSRA's range excludes two material categories of cost: (1) the fake tree (monopine) design premium, and (2) site items the August 2025 Board agenda lists separately rather than as construction. The monopine is the single biggest swing: whether the County and Coastal Commission require it, or accept a plainer pole, is genuinely uncertain.
- Monopine design premium (+$293K), pessimistic case only: a real but uncertain cost. Sonoma County has required fake trees in scenic areas, but the Coastal Commission has also preferred plainer poles elsewhere (in the Point Reyes review a plain pole was judged a better fit, and a plain steel pole was ultimately built).
- Steel tariff escalation: steel input costs have moved materially since the June 2025 feasibility study pricing.
- California construction cost inflation: standard CA construction escalation since the study date.
- Excluded site items ($143K-$303K): the access road, backup generator, fencing, fiber conduit, site clearing, tree removal, and permit fees. The August 2025 Board agenda excludes these from the construction estimate but they will still need to be paid.
- Overrun contingency: TSRA's Finance Committee rated this risk "high" in April 2025. Oxford's Bent Flyvbjerg, drawing on a 16,000-project database (How Big Things Get Done, 2023), finds roughly nine in ten large projects run over budget or behind schedule, with transportation overruns commonly 20% to 45%.
Calculator: optimistic preset uses $950,000; pessimistic uses $1,673,000
The April 2025 Finance Committee memo broke out approximately $100,000 in up-front non-construction costs as a line item within its total $600,000 "TSRA Out of Pocket" figure. The August 2025 Board agenda revised the total upward to $700K-$1M but no longer breaks the up-front items out separately.
- Consultants ($75K per April memo): Architecture, environmental, telecom counsel, land use counsel, survey, photosimulation, NEPA, FAA filings.
- Permits ($23K per April memo): Coastal Development Permit ($8K) + Building & Site Permits ($15K).
- FCC fees ($2K per April memo).
- Documented vendor spending through early 2026: Approximately $100K defensibly attributable to the cell tower project, with a realistic total likely $200K+ once attorney time is fully booked.
Industry-typical capital contributions are $50,000 to $150,000 per carrier, with $100,000 being a reasonable middle. If the lease negotiator's full fee structure (Model Input 6) is applied, the negotiator takes 50% of any one-time payment, including this contribution.
- TSRA's $300K-$500K range assumes 4 carriers at $75K-$125K each. Member analysis (Input 4) supports 3 carriers as the realistic count.
- Carriers in 2025-2026 are using aggressive negotiation on all financial terms, including up-front contributions.
- Net contribution to TSRA after the negotiator's 50% share: $50K-$75K per carrier, not $100K-$150K.
TSRA's assumption of 4 paying carriers does not match the addressable market. The U.S. has only three major facility-based carriers after the T-Mobile/UScellular merger closed August 1, 2025, all three already advertise LTE coverage at Sea Ranch, and only three firms responded to TSRA's own 2024 Expression of Interest.
- EOI received only three responses per the Davis-Stirling records inquiry and the December 2025 Part 1 communication.
- Verizon, AT&T, and T-Mobile all advertise LTE at Sea Ranch on their public coverage maps and the FCC's official mobile map.
- T-Mobile completed its acquisition of UScellular on August 1, 2025; the DOJ noted at closing that the "Big Three" now account for more than 90% of US mobile subscriptions.
- DISH/EchoStar declined a $326M interest payment in May 2025 and is selling spectrum to AT&T, making it an unlikely fourth tenant.
- Operating costs do not scale down if a carrier leaves; Moonraker's ~$67,500 typical-year OpEx is largely fixed regardless of tenant count.
Member presets: optimistic 3 · pessimistic 2
This is the single place where TSRA's assumption has diverged most sharply from current market reality. Multiple industry sources document a clear, persistent decline in new cell tower lease rates driven by carrier consolidation and the emergence of satellite direct-to-cell as a competing technology.
- Steel In The Air (2024): "Average of $1,050 per month or $12,600 per year" nationally. Source
- Vertical Consultants (Jan 2026): "$1,145 per month" ($13,740/yr) with a range of "$400 to $1,800 per month" ($4,800 to $21,600/yr). Source
- cell-tower-leases.com (2026 forecast): "Between $500 and $900 per month" ($6,000 to $10,800/yr). Source
- Carriers are negotiating hard: "Wireless carriers are more aggressive than ever in trying to renegotiate their leases. They hire third party optimization firms that are paid solely to get landowners to reduce their lease rates." Source
TSRA's range sits at or above the very top of every documented 2024 source and is substantially above the 2026 forecast.
Member presets: optimistic $22,000 · pessimistic $14,000
The records production produced the signed Letter of Engagement with the executive lease negotiator. It contains three layers of compensation, all of which reduce TSRA's net revenue:
- 20% of rental income for life of every lease executed under the engagement.
- 50% of any one-time payment, including the carrier capital contribution in Year 2 (Model Input 3).
- Initial Fee: the first 3 months of rent from each tenant.
The LOE was signed by TSRA after the Board's vote to proceed but before the engagement was publicly disclosed in the financial materials.
The Moonraker tower's operating statement (FY 2027-28 typical year, produced in the Davis-Stirling records production) gives a real, audited benchmark for what it costs to operate a Sea Ranch tower. Comparing line-by-line:
- Property taxes: $12,839 (Moonraker actual) / $13,000 (new tower est.)
- Insurance: $8,322 / $8,500
- Routine maintenance: $1,545 / $2,000
- Generator fuel + service: Unknown (no separate line in Moonraker statement; likely tenant-provided or bundled into routine maintenance) / $2,500 (new tower's 60 kW propane generator per the feasibility study)
- Site management labor: bundled in mgmt fee at Moonraker / $3,000 separately at new tower
- Capital reinvestment reserve: $0 typical year (lumpy reinvestment cycle) / $3,000 amortized
TSRA's $22K assumption matches the Moonraker baseline operating-only costs almost exactly, missing the new tower's generator costs, the management labor allocation, and the capital reinvestment reserve.
Member presets: optimistic $28,000 · pessimistic $36,000
Industry standard for cell tower rent escalation has historically been 3% annually, but recent industry data shows new leases are trending toward 2% as carriers push back on terms. The calculator uses 3% as a conservative central case.
- Carriers are "more aggressive than ever in trying to renegotiate their leases", including escalator terms.
- Lease optimization firms negotiate escalators down as a routine practice.
- Compounded over 30 years, the difference between 2% and 3% escalation is meaningful: a $25K rent in Year 1 becomes ~$45K at 2% or ~$58K at 3% in Year 30.
Member presets: optimistic 3.0% · pessimistic 2.0%
The target financial hurdle (the discount rate in financial terms) captures both the time value of money and the risk that projected cash flows might not materialize. A higher hurdle means the project is being treated as riskier, and the result is a lower Net Present Value. TSRA's implied 7% is appropriate for stable, financeable infrastructure; it is a major understatement of this project's risk profile.
From the April 2025 Finance Committee meeting materials: "Banks may not lend TSRA money for this project given TSRA has not previously built a cell tower."
- Lowest-risk infrastructure (roads, power grids, financeable utilities): 7% to 10% target return. Source
- Moderate-risk infrastructure (existing parking, existing data centers): 10% to 13%.
- Higher-risk infrastructure (new construction, technology displacement risk, no diversification): 14% or higher.
- Digital infrastructure funds (cell towers and data centers): median 14.0% per Cambridge Associates' November 2025 review.
This project carries multiple compounding risks: never-built, single-asset, construction risk, technology displacement, regulatory risk, demand risk, and concentration risk. 10% is conservative.
Member presets: optimistic 10% · pessimistic 14%
Net Present Value (NPV) is heavily weighted toward the later years of any long-lived project. Shortening the useful life by even five or ten years removes the most valuable part of the income stream. The cellular industry is in an active period of technological substitution, moving from ground-based cell towers to satellite direct-to-cell service:
- SpaceX and T-Mobile launched their first Direct-to-Cell satellites in January 2024 and made commercial service available July 23, 2025. More than 650 D2C satellites are now in orbit.
- AT&T-AST SpaceMobile: definitive commercial agreement signed May 2024; native voice/text call July 2025; beta service launching first half of 2026.
- Verizon-AST SpaceMobile: partnership May 2024; definitive direct-to-device agreement October 2025, service targeting 2026.
- Apple Emergency SOS via satellite has shipped on every iPhone since the iPhone 14 launched in November 2022.
- AT&T, T-Mobile, and Verizon announced a satellite-to-device joint venture in May 2026, pooling spectrum and partnerships to compete with Starlink. The three largest carriers organizing collectively around satellite is a strong industry signal that satellite is reshaping rural coverage economics.
Sea Ranch's north end has on the order of 200 to 300 lots within the proposed tower's primary service radius, the precise low-density rural coverage problem satellite direct-to-cell is designed to solve.
Member presets: optimistic 30 · pessimistic 20
What it does not include:
Self-funding from TSRA reserves. TSRA staff materials acknowledge that banks may not lend on this project given the association has not previously built a cell tower. Instead, TSRA has proposed a plan to fund the tower from Sea Ranch Connect revenue rather than letting that money retire the low-interest SRC loan early. That means members keep paying the $10 monthly SRC charge to bankroll a project that, by TSRA's own numbers, may never break even. The calculator measures the net present value of future cash flows but does not separately account for the financial and operational cost of self-funding $700K to $1M of up-front outlay while waiting years for carrier revenue to materialize.
Opportunity cost. Those same reserves could alternatively be used to:
Retire SRC (low-interest) loan debt early
Hold current HOA reserves into institutional high-yield cash accounts (currently earning ~3.50% - 4.00% APY as of May 2026; materially higher than the SRC loan rate)
Remain available for unanticipated capital needs across a 60-year-old community (roads, dead tree removal, facilities repairs)
Property value damage to nearby homes. TSRA's published financial analyses include no provision for property value impact on adjacent residences. The Member group's December 2025 communication estimated an aggregate property value loss of approximately $1.2 million, calculated as a conservative 2.5% impact applied across the 32 houses on the east side of Highway 1 (Deer Trail turn-off through West Wind) at an average value of $1.5 million per house. Peer-reviewed research cited this analysis supports an individual impact range of 4–9% for highly visible nearby towers, so this $1.2M aggregate is at the conservative end. The calculator does not net any of this against project NPV.