Every home in Discovery Bay depends on levees most buyers never think about. The community sits on the Byron Tract, protected by 19.2 miles of levees maintained by Reclamation District 800. Those levees shape the flood map, the flood insurance conversation, and a line on every property tax bill.

Here is what RD 800 does, how it is funded, what the flood map says, and what I would check on any Discovery Bay address before an offer.

What is Reclamation District 800?

RD 800 is a special district formed in 1909. It provides flood protection, drainage, water circulation and bay access services in and around Discovery Bay, and it is governed by a five-member board of trustees elected by property owners. The district states that it protects 6,933 acres with 19.2 miles of levees along Old River, Indian Slough and the dryland levee near Bixler Road.

Beyond the levees, the district runs the north and south pump stations, manages aquatic weeds and dredging for navigation, and reviews construction on and around levees and slopes. For homes on deep water or on Willow Lake, it also offers free rip-rap rock for erosion control, delivered to the driveway, with the homeowner responsible for placing it under the district's directions.

How is RD 800 funded, and what shows up on the tax bill?

RD 800 is funded by a share of property taxes, an annual assessment and state funding. In 2025 the district told owners its existing assessment, approved in 1999, had never increased and left a shortfall. Property owners voted on a new assessment in fall 2025, with ballots closing at a public hearing on October 23, 2025.

The district's notice of assessment for fiscal year 2026-27 lists two charges collected through the county tax bill:

  • The existing operation and maintenance assessment, $145.06 per residential parcel
  • A new maintenance and capital assessment, levied per Equivalent Benefit Unit, with each parcel's units based on factors such as land use, parcel and building size, floor elevation and location in the district's zones

The district states the new assessment can rise each year with inflation, capped at 4 percent. RD 800's website includes a calculator for a specific parcel.

What flood zone is Discovery Bay in?

RD 800 has stated that its levees are accredited by FEMA for a 100-year level of protection and that the area is mapped as a low to moderate risk flood zone. FEMA's own guidance explains that land behind an accredited levee is typically shown as Zone X (shaded), a moderate-hazard area.

Two points matter for buyers. First, flood insurance is mandatory for federally backed mortgages only in high-risk zones A and V, so a Zone X property usually does not trigger the requirement. Second, FEMA is clear that accreditation does not guarantee protection, and it notes that about one in three flood insurance claims come from low and moderate risk zones. Whether to insure is a separate decision from whether the lender requires it.

How do you check a specific Discovery Bay address?

  • FEMA's Flood Map Service Center. Enter the address to see the official flood zone on the current map.
  • Cal OES MyHazards. A free state tool that shows flood, fire and earthquake hazard layers for an address.
  • The Natural Hazard Disclosure report. California Civil Code 1103.2 requires the seller to disclose whether the property is in a FEMA Special Flood Hazard Area (any Zone A or V) or an area of potential flooding on a dam inundation map.
  • The tax bill. Look for the RD 800 charges and use the district's calculator if you want the new assessment for that parcel.
  • A flood insurance quote. Even where it is optional, get a quote during your contingency period so the cost is known.

For how flood zones and the hazard disclosure work across East County, see my guide to flood zones and Natural Hazard Disclosure in Brentwood. For the community itself, see Living in Discovery Bay.

Frequently asked questions about Discovery Bay levees and flood zones

Who maintains the levees around Discovery Bay?

Reclamation District 800, a special district formed in 1909 and governed by a board elected by property owners. It maintains 19.2 miles of levees protecting the Byron Tract.

Is flood insurance required in Discovery Bay?

Flood insurance is mandatory for federally backed mortgages only in FEMA high-risk zones A and V. RD 800 has stated the area is mapped low to moderate risk behind accredited levees, but check the FEMA map for the specific address.

What is the RD 800 assessment on my tax bill?

For fiscal year 2026-27, the district's notice lists an operation and maintenance assessment of $145.06 per residential parcel plus a new maintenance and capital assessment based on each parcel's Equivalent Benefit Units.

Can the RD 800 assessment go up?

The district states the new assessment can increase each year with inflation, capped at 4 percent.

Where do I check the flood zone for a Discovery Bay home?

Use FEMA's Flood Map Service Center or Cal OES MyHazards, and read the Natural Hazard Disclosure report the seller provides.

The Bottom Line on Discovery Bay Levees

Discovery Bay's levees are why most of the community is not in a high-risk flood zone, and they are also why every owner pays RD 800. Check the FEMA map for the address, read the hazard disclosure, look at both RD 800 lines on the tax bill, and get a flood insurance quote even if the lender does not ask for one.

Buying or selling in Discovery Bay?

See homes for sale in Discovery Bay

Send me an address and I will pull the flood zone and the tax bill charges before you make an offer.

Find out what your Discovery Bay home is worth

Or call or text 925-250-9611.

Sources

Reclamation District 800, About and History, for the district's role, governance and levee length. RD 800, Assessment and Notice of Assessment for 2026-2027, for the vote and current charges. RD 800, Rip-Rap Rock. RD 800 newsletter, February 2023, for FEMA accreditation. FEMA, levees and the NFIP and FloodSmart, flood zones. Cal OES MyHazards. California Civil Code 1103.2, Natural Hazard Disclosure.

Jaz Chand, Broker Associate | Homes With Accent
The Jaz Team at Merrill Signature Properties | DRE #01751823
Phone/Text: 925-250-9611 | Jaz@HomesWithAccent.com

General information only, not legal or insurance advice. Flood maps, assessments and insurance requirements change. Confirm the flood zone and charges for a specific address with FEMA, RD 800 and your insurance agent.