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Single Family ResidenceResidential
$764,623$217 / 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 96How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Aug 30, 2026
Last sold for $580,000 on May 31, 2019

3423 KEYSTONE LOOP

DISCOVERY BAY, CA 94505
5
Beds
4
Baths
3,517 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.
0.16 ac
Lot SizeThe size of the land the home sits on, from county records.
2003
Year BuiltThe year the home was originally built, according to county records.
2
StoriesHow many floors the home has above ground.
11
RoomsThe total room count in county records. Counties differ on which rooms they count, so compare it loosely.
2
ParkingThe number of parking spaces on the property, including the garage.

Valuation

$765K
$734K low$795K high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$580,000 · May 31, 2019

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$9,277 (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.$659,936 (2026)
Assessed LandThe share of the county's assessed value that comes from the land itself, not the buildings.$159,294
Assessed ImprovementsThe share of the county's assessed value that comes from the buildings and other structures on the land.$500,642
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$646,997

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.23
26
FloodProjected flooding risk from rivers, heavy rain, and storm surge, scored 0 to 100. Higher is riskier.
1
WildfireProjected wildfire risk, scored 0 to 100, based on how much land burns in a typical year. Higher is riskier.
46
HeatProjected heat risk, scored 0 to 100, based on how many extremely hot days a year are expected. Higher is riskier.
19
StormProjected risk from heavy rainstorms, scored 0 to 100, based on how often extreme rainfall is expected. Higher is riskier.
25
DroughtProjected water shortage risk, scored 0 to 100. Higher means more strain on the local water supply.
Projected Flood DepthHow deep a serious flood is expected to get here at some point in the next 30 years. Shown in inches.4 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
CountyCONTRA COSTA
Lot (acres)The size of the land the home sits on, from county records.0.16
CoolingThe type of cooling or air conditioning in the home.Central
GarageWhether the property has a garage, and details like whether it is attached to the home.Garage, Attached
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.

E
Timber Point Elementary SchoolB-
Elementary · Grades KG–5 · 0.5 mi
M
Excelsior Middle SchoolC-
Middle · Grades 6–8 · 2.9 mi
H
Liberty High SchoolB+
High · Grades 9–12 · 4.5 mi

District: Byron Union Elementary School District

Neighborhood · ZIP 94505These 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.100
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.84
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.340

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.92%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.22%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.6.3%
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.9,105
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.519 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$128,285
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$156,258
Average tempThe average temperature here across a full year.61°F
Annual precipHow much rain and melted snow falls here in a typical year.13 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

3423 Keystone Loop 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 66% of homes in Lakeshore
  • Among the lowest price per square foot in Contra Costa County
  • Bigger than 94% of homes in Contra Costa County
  • Has a bigger lot than 67% of homes in Lakeshore
  • Newer than 87% of homes in Contra Costa County

What homes are worth in Discovery Bay 94505

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

This home
$460K$1.6M

This home is worth more than 49% of homes in Discovery Bay 94505.

How it measures up in Discovery Bay 94505

The dot is this home. The mark in the middle is the typical home in Discovery Bay 94505.

Estimated value$764,623
CheaperTypical $769,241Pricier

Pricier than 49% of homes nearby

Price per ft²$217
CheaperTypical $331Pricier

Pricier than 3% of homes nearby

Living area3,517 ft²
SmallerTypical 2,420 ft²Bigger

Bigger than 90% of homes nearby

Lot size0.16 ac
SmallerTypical 0.16 acBigger

Bigger than 42% of homes nearby

Year built2003
OlderTypical 1993Newer

Newer than 73% of homes nearby

How 3423 Keystone Loop ranks against every home in each area.
MeasureThis homeLakeshoreDiscovery Bay 94505Contra Costa County
Estimated valuepricier than$764,62366% of homes49% of homes52% of homes
Price per ft²pricier than$21718% of homes3% of homesalmost no homes
Living areabigger than3,517 ft²76% of homes90% of homes94% of homes
Lot sizebigger than0.16 ac67% of homes42% of homes53% of homes
Year builtnewer than200375% of homes73% of homes87% of homes

About 3423 Keystone Loop

How much is 3423 Keystone Loop, Discovery Bay, CA worth?

The TopHap Estimate for 3423 Keystone Loop, Discovery Bay, CA is $764,623 as of Aug 30, 2026. The likely range is $734,097 to $795,149. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 3423 Keystone Loop, Discovery Bay, CA last sell?

3423 Keystone Loop, Discovery Bay, CA last sold on May 31, 2019 for $580,000, according to the county's recorded deed. TopHap holds 2 recorded sales for this parcel.

How big is 3423 Keystone Loop, Discovery Bay, CA?

3423 Keystone Loop, Discovery Bay, CA has 5 bedrooms, 4 bathrooms, 3,517 square feet of living space and a 0.16-acre lot.

When was 3423 Keystone Loop, Discovery Bay, CA built?

3423 Keystone Loop, Discovery Bay, CA was built in 2003, making it 23 years old. The building has 2 stories.

What schools serve 3423 Keystone Loop, Discovery Bay, CA?

3423 Keystone Loop, Discovery Bay, CA is assigned to Timber Point Elementary School (elementary), rated B-; Excelsior Middle School (middle), rated C-; Liberty High School (high), rated B+. All sit in Byron Union Elementary School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 3423 Keystone Loop, Discovery Bay, CA compare to other homes in Discovery Bay 94505?

Among the 6,088 homes in Discovery Bay 94505, it is worth more than 49% of them ($764,623 against a typical $769,241), its price per square foot is higher than 3% of them ($217 against a typical $331), it is bigger than 90% of them (3,517 ft² against a typical 2,420 ft²), its lot is bigger than 42% of them (0.16 ac against a typical 0.16 ac) and it is newer than 73% of them (2003 against a typical 1993). Measured against all of Contra Costa County, it is worth more than 52% 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 3423 Keystone Loop, Discovery Bay, CA?

The 2025 property tax bill for 3423 Keystone Loop, Discovery Bay, CA was $9,277. The county assessed it at $659,936.

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