Bay Farm Island, Alameda vs Castro Valley
Bay Farm Island, Alameda carries an effective property tax rate of 1.22% of assessed value and Castro Valley carries 1.20%, both for fiscal year 2025-26. On one identical reference loan the monthly carrying costs are $9,917 and $9,893 — $24 apart, with Castro Valley lower. To Oakland City Center at AM peak the fastest published commutes are 20 min by car from Bay Farm Island, Alameda and 28 min by BART from Castro Valley. Every figure is an objective public metric or arithmetic on one, and names its source.
Bay Farm Island, Alameda (Alameda County) · Castro Valley (Alameda County)
| Metric | Bay Farm Island, Alameda | Castro Valley | Difference |
|---|---|---|---|
| Median $/sqft (SFR) | $750 | $650 | +$100 |
| Effective tax rate | 1.22% | 1.20% | +0.018% |
| Monthly cost, reference loan | $9,917 | $9,893 | +$24 |
| FiDi SF (Montgomery St BART) — BART | 45 min | 45 min | 0 min |
| FiDi SF (Montgomery St BART) — Drive | 40 min | 50 min | −10 min |
| Oakland City Center (12th St BART) — BART | 35 min | 28 min | +7 min |
| Oakland City Center (12th St BART) — Drive | 20 min | 28 min | −8 min |
| Sunnyvale / Mountain View (Sunnyvale Caltrain) — Drive | 55 min | 50 min | +5 min |
Difference is Bay Farm Island, Alameda minus Castro Valley. Sources are cited on each submarket page.
Put the two side by side and the gap is square footage, not tax: $750 per foot in Alameda (Bay Farm) against $650 in Castro Valley. On the same $1,600,000 purchase the monthly separation is only $24, because Alameda (Bay Farm) bills 1.22% and Castro Valley 1.20%.
The house at each price
Bay Farm comps run $800-$900 per square foot detached and the high $600s for lagoon townhomes. The Castro Valley flats near the Boulevard run $950K-$1.1M for a 1,500-1,800 sq ft 1950s ranch on 6,000 sq ft. The median foot costs $750 in Alameda (Bay Farm) against $650 in Castro Valley; on a 2,000 sq ft house that is $200,000 of purchase price.
The monthly, matched
Holding the loan constant — $1,600,000, 20% down, 6.5% on a 30-year fixed, $2,400 of insurance, no HOA — Alameda (Bay Farm) totals $9,917 a month at 1.22% and Castro Valley $9,893 at 1.20% — tax lines of $1,627 and $1,603. The Bay Farm lagoon villages carry extra lagoon maintenance on top of base dues. Palomares Hills and Five Canyons dues run $100-$200 a month with pool and trail maintenance.
Commute, measured
To FiDi SF (Montgomery St BART): 35 minutes by ferry from Alameda (Bay Farm), 45 by BART from Castro Valley — a 10-minute edge to Alameda (Bay Farm), or 1.7 hours across a ten-trip week. Doolittle to I-880 or the Posey Tube gets Bay Farm to Oakland City Center in 15 minutes off-peak; the tube backs up 7:30-9:00. Door to door from the Castro Valley flats to FiDi is 50 minutes; from Palomares Hills add 10-15 minutes to the station.
Hazard and insurance
Standard fire carriers are still writing Bay Farm without the hills' non-renewal wave. The Hayward Fault runs through the west side of Castro Valley and is on every disclosure. Run the address through CAL FIRE's severity-zone viewer, the FEMA Flood Map Service Center and the CGS seismic hazard maps, and treat the premium quote as a contingency item.
Choosing between them
Bay Farm is the option when the water crossing is the commute. Castro Valley is the answer when a view lot and a rail station both have to fit one budget.
Sources. Rate and payment figures: Alameda County Tax Rates by TRA FY 2025-26, as composited in build/assets/metrics.json — unverified at tax-rate-area level, so read the bill. Minutes shown are AM-peak and door to door, from data/commute/static.csv. Price per square foot is a trailing median and is not an appraisal. Qualitative detail is the broker's own field observation.
Compare any two submarkets
| Metric | Bay Farm Island, Alameda | Castro Valley |
|---|---|---|
| Median $/sqft (SFR) | $750 | $650 |
| Effective tax rate | 1.22% | 1.20% |
| Monthly cost, reference loan | $9,917 | $9,893 |
| Fastest to FiDi SF (Montgomery St BART) | 35 min | 45 min |
| Fastest to Oakland City Center (12th St BART) | 20 min | 28 min |
| Fastest to Sunnyvale / Mountain View (Sunnyvale Caltrain) | 55 min | 50 min |
Same reference loan on both sides; the tax line is the only variable. Commute figures are door-to-door AM-peak estimates. Sources are listed on each submarket page.
Bay Farm Island, Alameda detail
| Component | Rate of assessed value |
|---|---|
| Prop 13 general levy | 1.000% |
| County / city voter-approved bonds | 0.042% |
| School district measures | 0.178% |
| Effective rate | 1.22% |
| Mello-Roos / CFD | None recorded |
Source: Alameda County Tax Rates by TRA FY 2025-26 (Alameda County), composited in
build/assets/metrics.json.
Tax Rate Area not yet verified parcel-by-parcel — confirm the rate on the parcel’s own tax bill.
Castro Valley detail
| Component | Rate of assessed value |
|---|---|
| Prop 13 general levy | 1.000% |
| County / city voter-approved bonds | 0.042% |
| School district measures | 0.160% |
| Effective rate | 1.20% |
| Mello-Roos / CFD | None recorded |
Source: Alameda County Tax Rates by TRA FY 2025-26 (Alameda County), composited in
build/assets/metrics.json.
Tax Rate Area not yet verified parcel-by-parcel — confirm the rate on the parcel’s own tax bill.
Bay Farm Island, Alameda vs Castro Valley: questions and answers
- Which has the lower effective property tax rate, Bay Farm Island, Alameda or Castro Valley?
- Castro Valley, at 1.20% of assessed value against 1.22% for fiscal year 2025-26 — a gap of 0.020%. Rates are composited from county tax rate books; each parcel bill governs.
- How much do monthly carrying costs differ between Bay Farm Island, Alameda and Castro Valley?
- $24 per month on the identical reference loan: Bay Farm Island, Alameda $9,917, Castro Valley $9,893. Castro Valley is lower. Principal and interest are held constant, so the difference is the tax line. Arithmetic only.
- Which has the shorter commute to Oakland City Center, Bay Farm Island, Alameda or Castro Valley?
- Bay Farm Island, Alameda. Bay Farm Island, Alameda is 20 min by car; Castro Valley is 28 min by BART. Door-to-door, AM peak. Source: data/commute/static.csv.
- What is the price per square foot difference between Bay Farm Island, Alameda and Castro Valley?
- $100 per square foot: Bay Farm Island, Alameda $750, Castro Valley $650. Single-family medians, trailing twelve months. A median is not a valuation of any specific property.