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Single Family ResidenceResidential
$1,935,265$706 / ft²
TopHap EstimateOur estimate of what this home would sell for today, based on nearby sales, the home's size and features, and local price trends. It is a starting point, not an appraisal.· confidence 89How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Oct 21, 2026

604 FORTRESS ISLE

ALAMEDA, CA 94501
5
Beds
3.5
Baths
2,740 ft²
Living AreaTotal finished area of the structures, from county records. Some counties include shared space like hallways or a building gym, so it may not match a listing.
0.14 ac
Lot SizeThe size of the land the home sits on, from county records.
1971
Year BuiltThe year the home was originally built, according to county records.
2
StoriesHow many floors the home has above ground.
9
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.

Valuation

$1.9M
$1.7M low$2.2M high

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$12,408 (2025)
Assessed ValueThe value the county assigns to this home to calculate property tax. It is often lower than what the home would sell for.$797,479 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$204,993
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$599,486
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$781,706
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$1,853,190

Climate Risk

Projected Flood DepthHow deep a serious flood is expected to get here at some point in the next 30 years. Shown in inches.11 in
30-Year Flood ChanceThe chance of at least one serious flood here in the next 30 years, not in any single year.6%
FEMA Flood ZoneFEMA's flood zone for this address. Zones starting with A or V are high risk, and lenders usually require flood insurance there.0.2 percent flood zone

Scores 0–100; higher = greater projected risk.

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Single Family Residence
CountyALAMEDA
Effective Year BuiltAn adjusted build year that accounts for condition and major remodels. A big renovation can make a home count as newer than it is.1981
Lot (acres)The size of the land the home sits on, from county records.0.14
ConstructionThe main material the home's frame and walls are built from.Wood (Unspecified)
HeatingThe type of heating system in the home.Forced Air With Air Conditioning
FireplaceWhether the home has a fireplace, and what kind.Yes
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(5)

Sales and refinances filed with the county for this home. Not every transfer is a normal sale, so check the type before comparing prices.

Assigned SchoolsThe public schools this address is zoned for. Boundaries change, so confirm with the district before you count on it.

M
Wood Middle SchoolB+
Middle · Grades 6–8 · 0.2 mi
E
Franklin Elementary SchoolA
Elementary · Grades KG–5 · 0.4 mi
H
Alameda High SchoolA
High · Grades 9–12 · 0.7 mi

District: Alameda City Unified School District

Neighborhood · ZIP 94501These are comparison scores, not percentages. 100 equals the national average, so 150 means about 50% above average.

CrimeLocal crime compared with the rest of the country, where 100 is average. It reflects things like population density, income, and how crime gets reported.124
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.88
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.409

Index scale: 100 = US average (tick). Lower is better.

Homes occupiedThe share of homes here that someone lives in. The rest sit empty, including vacation and for-sale homes.93%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.35%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.8.8%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.1.4%
PopulationHow many people live in this area.61,491
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.5,332 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$122,273
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$153,309
Average tempThe average temperature here across a full year.58°F
Annual precipHow much rain and melted snow falls here in a typical year.20 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.78%

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Data by ATTOM. Valuations are automated estimates, not appraisals. Photos from Google Street View and may not depict the current property state.

How this home compares

604 Fortress Isle measured against every home in its neighborhood, its ZIP code and its county, using county assessor records refreshed nightly. A home can stand out in one of those areas and look ordinary in another, because each one holds a different mix of homes.

  • Worth more than 95% of homes in Alameda 94501
  • Bigger than 88% of homes in Alameda County
  • Has a smaller lot than 65% of homes in Bronze Coast
  • Newer than 96% of homes in Bronze Coast

What homes are worth in Alameda 94501

Each bar is how many homes fall in that price range. The marker is this home.

This home
$401K$2.3M

This home is worth more than 95% of homes in Alameda 94501.

How it measures up in Alameda 94501

The dot is this home. The mark in the middle is the typical home in Alameda 94501.

Estimated value$1,935,265
CheaperTypical $1,139,109Pricier

Pricier than 95% of homes nearby

Price per ft²$706
CheaperTypical $726Pricier

Pricier than 45% of homes nearby

Living area2,740 ft²
SmallerTypical 1,652 ft²Bigger

Bigger than 86% of homes nearby

Lot size0.14 ac
SmallerTypical 0.11 acBigger

Bigger than 64% of homes nearby

Year built1971
OlderTypical 1935Newer

Newer than 79% of homes nearby

How 604 Fortress Isle ranks against every home in each area.
MeasureThis homeBronze CoastAlameda 94501Alameda County
Estimated valuepricier than$1,935,26584% of homes95% of homes90% of homes
Price per ft²pricier than$70654% of homes45% of homes60% of homes
Living areabigger than2,740 ft²69% of homes86% of homes88% of homes
Lot sizebigger than0.14 ac35% of homes64% of homes49% of homes
Year builtnewer than197196% of homes79% of homes60% of homes

About 604 Fortress Isle

How much is 604 Fortress Isle, Alameda, CA worth?

The TopHap Estimate for 604 Fortress Isle, Alameda, CA is $1,935,265 as of Oct 21, 2026. The likely range is $1,714,213 to $2,156,317. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 604 Fortress Isle, Alameda, CA last sell?

604 Fortress Isle, Alameda, CA last sold on Jan 1, 1900, according to the county's recorded deed.

How big is 604 Fortress Isle, Alameda, CA?

604 Fortress Isle, Alameda, CA has 5 bedrooms, 3.5 bathrooms, 2,740 square feet of living space and a 0.14-acre lot.

When was 604 Fortress Isle, Alameda, CA built?

604 Fortress Isle, Alameda, CA was built in 1971, making it 55 years old. The building has 2 stories.

What schools serve 604 Fortress Isle, Alameda, CA?

604 Fortress Isle, Alameda, CA is assigned to Wood Middle School (middle), rated B+; Franklin Elementary School (elementary), rated A; Alameda High School (high), rated A. All sit in Alameda City Unified School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 604 Fortress Isle, Alameda, CA compare to other homes in Alameda 94501?

Among the 14,889 homes in Alameda 94501, it is worth more than 95% of them ($1,935,265 against a typical $1,139,109), its price per square foot is higher than 45% of them ($706 against a typical $726), it is bigger than 86% of them (2,740 ft² against a typical 1,652 ft²), its lot is bigger than 64% of them (0.14 ac against a typical 0.11 ac) and it is newer than 79% of them (1971 against a typical 1935). Measured against all of Alameda County, it is worth more than 90% of homes there. These shares are recounted nightly from the full county assessor record for each area, not from active listings.

What are the property taxes on 604 Fortress Isle, Alameda, CA?

The 2025 property tax bill for 604 Fortress Isle, Alameda, CA was $12,408. The county assessed it at $797,479.

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