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Single Family ResidenceResidential
$831,211$434 / 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 97How 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
Last sold for $780,000 on Jun 30, 2020

18 PROSPECT AVE

PORT COSTA, CA 94569
3
Beds
2
Baths
1,916 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.
0.11 ac
Lot SizeThe size of the land the home sits on, from county records.
1900
Year BuiltThe year the home was originally built, according to county records.
2
StoriesHow many floors the home has above ground.
7
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.

Valuation

$831K
$808K low$855K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$780,000 · Jun 30, 2020

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$12,309 (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.$872,047 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$423,893
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$448,154
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$854,949

Climate Risk

Overall riskThe average of the five hazard scores below, on a 0 to 100 scale. Higher means greater projected risk over the coming decades.35
1
FloodProjected flooding risk from rivers, heavy rain, and storm surge, scored 0 to 100. Higher is riskier.
81
WildfireProjected wildfire risk, scored 0 to 100, based on how much land burns in a typical year. Higher is riskier.
37
HeatProjected heat risk, scored 0 to 100, based on how many extremely hot days a year are expected. Higher is riskier.
42
StormProjected risk from heavy rainstorms, scored 0 to 100, based on how often extreme rainfall is expected. Higher is riskier.
14
DroughtProjected water shortage risk, scored 0 to 100. Higher means more strain on the local water supply.

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
CountyCONTRA COSTA
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.1980
Lot (acres)The size of the land the home sits on, from county records.0.12
PoolWhether the property has a pool, and what kind, such as in-ground.No

Transaction History(6)

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
Carquinez Middle SchoolD
Middle · Grades 6–8 · 2.0 mi
H
John Swett High SchoolB-
High · Grades 9–12 · 2.0 mi
E
Rodeo Hills ElementaryD
Elementary · Grades KG–5 · 4.7 mi

District: John Swett Unified School District

Neighborhood · ZIP 94569These 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.146
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.87
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.365

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.97%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.28%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.6.1%
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.447
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.257 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$94,301
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$133,290
Average tempThe average temperature here across a full year.58°F
Annual precipHow much rain and melted snow falls here in a typical year.22 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

18 Prospect Ave 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.

  • Has a smaller lot than 73% of homes in Contra Costa County
  • Among the oldest homes in Contra Costa County

What homes are worth in Contra Costa County

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

This home
$350K$1.2M

This home is worth more than 88% of homes in Contra Costa County.

How it measures up in Contra Costa County

The dot is this home. The mark in the middle is the typical home in Contra Costa County.

Estimated value$831,211
CheaperTypical $736,482Pricier

Pricier than 59% of homes nearby

Price per ft²$434
CheaperTypical $457Pricier

Pricier than 45% of homes nearby

Living area1,916 ft²
SmallerTypical 1,755 ft²Bigger

Bigger than 57% of homes nearby

Lot size0.11 ac
SmallerTypical 0.15 acBigger

Bigger than 27% of homes nearby

Year built1900
OlderTypical 1977Newer

Older than almost all homes nearby

How 18 Prospect Ave ranks against every home in each area.
MeasureThis homeContra Costa County
Estimated valuepricier than$831,21159% of homes
Price per ft²pricier than$43445% of homes
Living areabigger than1,916 ft²57% of homes
Lot sizebigger than0.11 ac27% of homes
Year builtnewer than1900almost no homes

About 18 Prospect Ave

How much is 18 Prospect Ave, Port Costa, CA worth?

The TopHap Estimate for 18 Prospect Ave, Port Costa, CA is $831,211 as of Oct 21, 2026. The likely range is $807,502 to $854,920. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 18 Prospect Ave, Port Costa, CA last sell?

18 Prospect Ave, Port Costa, CA last sold on Jun 30, 2020 for $780,000, according to the county's recorded deed. TopHap holds 3 recorded sales for this parcel.

How big is 18 Prospect Ave, Port Costa, CA?

18 Prospect Ave, Port Costa, CA has 3 bedrooms, 2 bathrooms, 1,916 square feet of living space and a 0.12-acre lot.

When was 18 Prospect Ave, Port Costa, CA built?

18 Prospect Ave, Port Costa, CA was built in 1900, making it 126 years old. The building has 2 stories.

What schools serve 18 Prospect Ave, Port Costa, CA?

18 Prospect Ave, Port Costa, CA is assigned to Carquinez Middle School (middle), rated D; John Swett High School (high), rated B-; Rodeo Hills Elementary (elementary), rated D. All sit in John Swett Unified School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 18 Prospect Ave, Port Costa, CA compare to other homes in Contra Costa County?

Among the 349,702 homes in Contra Costa County, it is worth more than 59% of them ($831,211 against a typical $736,482), its price per square foot is higher than 45% of them ($434 against a typical $457), it is bigger than 57% of them (1,916 ft² against a typical 1,755 ft²), its lot is bigger than 27% of them (0.11 ac against a typical 0.15 ac) and it is newer than almost none of them (1900 against a typical 1977). These shares are recounted nightly from the full county assessor record for each area, not from active listings.

What are the property taxes on 18 Prospect Ave, Port Costa, CA?

The 2025 property tax bill for 18 Prospect Ave, Port Costa, CA was $12,309. The county assessed it at $872,047.

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Closest homes

More homes in Port Costa 94569

Assigned schools

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