How to Buy a Home Near the Tijuana River and the South Bay Coast: Sewage, Odors, Flood Zones and the Fixes on the Way

On October 19, 2026, San Diego County introduced Bridget Premont, a career U.S. diplomat, as its first County Pollution Crisis Chief, a new job created to coordinate the response to sewage and pollution coming down the Tijuana River. Times of San Diego reported that she once led political and economic affairs at the U.S. Consulate General in Tijuana (2017 to 2021). At the same press conference, Supervisor Paloma Aguirre, a former mayor of Imperial Beach, said, "It has always been a crisis, but the scale is getting worse every day."

The appointment caps a busy fall. On September 1, county supervisors voted 4 to 1 to spend $1.8 million designing a system that would divert and treat the river before it reaches U.S. neighborhoods, and they unanimously approved $4 million to fix the Saturn Boulevard sewage hot spot, according to CalMatters. On September 27, county health officials closed the Imperial Beach shoreline to water contact after the river began flowing into the surf zone again. On September 30, the U.S. EPA reported that Tijuana's Parallel Gravity Line was finished in August 2026 and that the second phase of the Tijuana River gates was under construction. And on November 3, county voters will decide Measure B, a half-cent sales tax that would send up to 22.5% of its revenue to Tijuana River sewage work.

For home buyers, all this raises a fair question we hear often at Choice of America: "Should I buy in Imperial Beach, Nestor, San Ysidro, Otay Mesa West or Coronado while this is still going on, and how do I protect myself if I do?" South County has some of the best-priced coastal and near-coastal homes in San Diego County, and right now some of the most negotiable sellers. But you need to know what you're buying into. This guide covers the market numbers, what the pollution means for daily life, flood zones heading into a strong El Niño winter, your disclosure rights, and a step-by-step plan.

The market snapshot (September 2026, Realtor.com)

Countywide, San Diego County's median listing price was $888,450 in September 2026, down 6.3% from a year earlier. The median home spent 46 days on the market, 20.4% of listings had a price cut (Realtor.com's price_reduced_share), and there were 5,749 active listings.

Here is how the South Bay ZIP codes compare:

Source: Realtor.com Residential Data, county and ZIP core metrics, September 2026. ZIP 92154 is a large ZIP code that includes Nestor, Otay Mesa West, Egger Highlands and the Tijuana River Valley along with neighborhoods farther from the river. San Ysidro (92173) had only 17 active listings and Realtor.com flagged its data for quality, so we left it out of the table. Small ZIP codes swing from month to month; treat these as a guide, not a verdict.

What jumps out: in Imperial Beach, the ZIP closest to the river mouth, about one in three listings (33.9%) had a price cut in September, compared with about one in five countywide, and homes there took 58 days to sell versus 46 for the county. That doesn't prove the sewage crisis is the only reason, but it does mean many Imperial Beach sellers have already had to adjust. Buyers who do their homework have room to negotiate.

The payment math at today's rates

Freddie Mac's Primary Mortgage Market Survey put the average 30-year fixed rate at 7.32% on October 22, 2026, the latest weekly reading available as of this writing. Here is principal and interest (P&I) on a 30-year fixed loan at that rate:

The formula, so you can run your own price: monthly P&I = L × r ÷ (1 − (1 + r)^−360), where L is the loan amount (price minus down payment) and r is the annual rate divided by 12 (0.0732 ÷ 12 = 0.0061). Property tax uses California's 1% base rate under Proposition 13; your actual bill will be higher once local voter-approved bonds and any special assessments on the tax bill are added. These figures leave out homeowners insurance, flood insurance (if you need it), HOA dues and mortgage insurance. Coronado's $3,084,000 median would require a jumbo loan well above conforming limits, so its rate and down payment rules would be different; ask a lender for a quote.

What the Tijuana River crisis means for a homeowner

The water. The river carries untreated sewage, trash, sediment, industrial chemicals and runoff from Tijuana into the Tijuana River Valley and out to the ocean near Imperial Beach. The county's Department of Environmental Health and Quality (DEHQ) closes beaches when the river reaches recreational waters or when testing shows sewage contamination. As of early October 2026, the ocean shoreline at Border Field State Park and the Tijuana Slough National Wildlife Refuge remained closed to water contact, and the wider Imperial Beach shoreline had been closed again on September 27. If surfing, swimming or beach days are a big reason you're buying, know that water closures in Imperial Beach can last a long time.

The air. The rotten-egg smell residents describe comes mostly from hydrogen sulfide (H2S), a gas given off by decomposing sewage. The San Diego County Air Pollution Control District (SDAPCD) measures H2S around the clock at three sites: Fire Station 29 in San Ysidro, Berry Elementary School in Nestor, and the Imperial Beach Civic Center. It posts hourly averages online and issues H2S air quality advisories when levels could affect health. According to Times of San Diego, researchers from UC San Diego, San Diego State, UC Riverside and other institutions published findings in Science showing elevated H2S in parts of the valley, and hundreds of other chemical compounds in the air over the valley and the nearby coast. SDAPCD has also issued Notices of Violation to the U.S. International Boundary and Water Commission (USIBWC) and its contractor Veolia, alleging public nuisance violations.

The cost to the region. A county-commissioned study estimated that pollution tied to the river causes up to $503.5 million a year in economic losses and could top $7.9 billion over two decades if nothing changes, Times of San Diego reported.

The fixes, and their timelines. This matters to a buyer because the problem is being worked on, but on a multi-year schedule. According to the EPA's September 30, 2026 quarterly update:

• The South Bay International Wastewater Treatment Plant was expanded to 35 million gallons per day (MGD) in August 2025. The first major construction contract for the next expansion, to 50 MGD, was awarded in September 2026, with the full design on track for approval in October 2026.
• The Parallel Gravity Line in Tijuana was completed in August 2026. The UCSD Guardian reported that this main pipeline collapsed in two places in May 2026, releasing millions of gallons of untreated sewage.
• Phase 2 of the Tijuana River gates, which are meant to keep an estimated 5 MGD of flows out of the river, began construction in September 2026 and is on track for early 2027.
• Pump Station 1 in Tijuana is on track for November 2027, and the La Morita and Arturo Herrera effluent relocation, which moves 10 MGD of treated wastewater away from the river, is on track for December 2027.
• EPA says border treatment capacity has more than doubled to 53 MGD and that daily average dry-season flows were down 54% in 2025-2026 compared with 2022-2024.

Locally, the county is designing its own system to divert and treat the river. Measure B on the November 3 ballot would add a half-cent countywide sales tax estimated to raise $400 million to $450 million a year, with no end date unless voters repeal it. Up to 60% would go to health care, nutrition and family services, up to 22.5% to Tijuana River sewage programs, up to 17.5% to public safety and wildfire work, and up to 1.5% to administration. Board Chair Terra Lawson-Remer told CalMatters that the annual revenue could back $700 million to $1 billion in bonds for treatment facilities. Two things for buyers to understand: Measure B is a sales tax, not a property tax, so it would not show up on your property tax bill; and whether it passes or fails, new treatment works take years to design and build.

The flood question heading into El Niño

NOAA's Climate Prediction Center says a strong-to-very strong El Niño is likely through January to March 2027, and its October 15 outlook shows elevated odds of above-normal rain for much of California. The EPA says it and the USIBWC are coordinating with agencies in San Diego and Tijuana to get ready for "a potentially strong El Niño winter expected to bring heavy rain and a heightened risk of flooding from October through April." Rain matters twice in South County: it raises the risk of local flooding, and when the river flows, contaminated water reaches the beaches.

What you need to know about flood zones and insurance:

• FEMA's flood maps divide land into zones. A Special Flood Hazard Area is any Zone "A" or Zone "V." California's Natural Hazard Disclosure Statement (Civil Code 1103.2) requires the seller to tell you whether the property is in one, or in an area of potential flooding on a dam failure inundation map.
• If the home is in a Special Flood Hazard Area and you're getting a government-backed mortgage, your lender must require flood insurance. Lenders can also require it outside those zones as a matter of their own policy.
• A standard homeowners policy does not cover flood. National Flood Insurance Program (NFIP) building coverage goes up to $250,000 and contents coverage up to $100,000.
• NFIP policies normally take effect 30 days after purchase, but there is no waiting period if you buy the policy when you take out, increase, extend or renew a mortgage. In practice, if you want flood coverage, buy it as part of your home purchase.

How to buy a home near the Tijuana River, step by step

Step 1: Map the address before you fall for the house

Distance and direction matter. A home a few blocks from the river valley or the Saturn Boulevard area may live with the problem very differently from one several miles north or inland.

How to do it:

• Find the address on a map in relation to the Tijuana River Valley, the estuary and Saturn Boulevard.
• Check whether the address is in SDAPCD's Air Improvement Relief Effort (AIRE) area: most of Otay Mesa West, San Ysidro, Egger Highlands, Nestor, the Tijuana River Valley and the City of Imperial Beach. Being in that area tells you the air district considers it affected.
• Look up the property on the FEMA Flood Map Service Center (msc.fema.gov) and note the flood zone.
• Ask your agent to order the Natural Hazard Disclosure report early, not at the end of escrow.

Step 2: Check the air and the water at different times

One sunny afternoon showing is not enough. Odors and closures change with weather, river flow and the season.

How to do it:

• Visit the neighborhood at least three times: early morning, evening and after a rain if you can. Stand outside with the windows of the house open and closed.
• Look at SDAPCD's H2S monitoring dashboard for the nearest station (San Ysidro, Nestor or Imperial Beach) and read its Community Hydrogen Sulfide Guidance for what each level means.
• Sign up for SDAPCD's H2S air quality alerts while you shop, so you see what an owner would see.
• Check sdbeachinfo.com (or call 619-338-2073) for current beach closures and advisories, and look back at recent closure history for the beaches you'd use.
• Talk to neighbors. Ask how often the smell is bad, at what time of day, and whether it gets inside.

Step 3: Read the disclosures closely and ask follow-up questions in writing

How to do it:

• In California's Real Estate Transfer Disclosure Statement, look at item 11, "Neighborhood noise problems or other nuisances," and the items on flooding, drainage or grading problems and major damage from floods or other disasters. If the seller checked "No" on nuisances in a ZIP code with documented odor problems, ask them to explain in writing.
• In the Natural Hazard Disclosure, check the Special Flood Hazard Area and dam inundation boxes.
• Ask the seller for any flood insurance declarations, flood claims history, odor-related repairs (for example, HVAC filtration or sealing work), and whether they received air purifiers through the AIRE program.
• Know your timeline. Under Civil Code 1102.3, if a required disclosure or a material amendment is delivered after you make your offer, you have three days after delivery in person, or five days after delivery by mail or electronically, to cancel the offer in writing.

Step 4: Price flood insurance and homeowners insurance before you remove contingencies

How to do it:

• Get a homeowners insurance quote and, separately, a flood insurance quote, whether or not the lender requires one. All NFIP insurers charge the same rate for the same home, so one agent's quote is a good starting point; private flood insurers may also quote.
• Ask the seller whether the home has an elevation certificate. FEMA says it isn't required to buy flood insurance, but it can lower the price.
• Have the policy ready to bind at closing so you avoid the 30-day wait.
• Add the premiums to your monthly budget from Step 6.

Step 5: Inspect for water, drainage and indoor air

How to do it:

• Get a general home inspection and ask the inspector to pay close attention to grading, drainage, gutters, crawl spaces and signs of past water intrusion.
• Have an HVAC contractor look at the heating and cooling system and whether better filtration can be added. SDAPCD points AIRE participants to California Air Resources Board (CARB) guidance on setting up a "clean air room" and on air cleaners that remove odors and gases.
• Check windows and doors for gaps; a well-sealed home helps when outdoor air is bad.
• For older coastal homes, check for corrosion on metal, electrical panels and water heaters. Elevating a water heater or electrical panel can also help reduce flood insurance costs, according to FloodSmart.

Step 6: Run your full monthly budget

How to do it:

• Start with P&I from the table above or your own price using the formula.
• Add property tax (1% base plus anything on the current tax bill), homeowners insurance, flood insurance, HOA dues and mortgage insurance if you put less than 20% down.
• Add a small line for air purifier filters and extra HVAC filter changes if you'll be near the valley.
• Make sure the payment still works if you have to stay put longer than planned. Imperial Beach homes took a median 58 days to sell in September.

Step 7: Negotiate with the data on your side

How to do it:

• Look up how long the home has been listed and whether it's already had a price cut. One in three Imperial Beach listings had one in September.
• Use what you learned in Steps 2 through 5. Odor complaints in disclosures, a flood zone, drainage problems or a required flood policy are fair reasons to ask for a lower price, a repair credit, or a seller credit toward closing costs or a rate buydown.
• Keep your inspection, insurance, appraisal and loan contingencies in place until you have your insurance quotes and disclosure answers.

Step 8: Buy for today's conditions, not for promised fixes

How to do it:

• Treat future improvements (the river gates in early 2027, the 50 MGD plant expansion, the county's own treatment system, Measure B) as possible upside, not as part of the price you pay.
• Ask yourself: "Would I be happy living here for five years if conditions stay about where they are now?" If the answer is no, keep looking.
• Follow the County Pollution Crisis Chief's office, EPA's quarterly updates and the November 3 Measure B result so you know what's actually funded and built.

Step 9: After you move in

How to do it:

• If you're in the AIRE program area, apply for free air purifiers and replacement filters. SDAPCD gives priority to households with children, people over 65 and the communities closest to the valley. Supplies are limited and the portal may close early.
• Keep H2S alerts and sdbeachinfo.com bookmarked.
• Renew your flood policy on time. NFIP policies last one year, with a 30-day grace period to renew.
• Report odors to SDAPCD. The district says it has responded to thousands of odor complaints, and those complaints led to its Notices of Violation.

Mistakes to avoid

• Touring only on a clear afternoon and never checking the H2S dashboard, beach status or the neighborhood at night.
• Assuming a seller's "No" on the nuisance question settles the matter.
• Skipping a flood quote because the lender didn't require one, or buying flood insurance after closing and facing a 30-day wait during El Niño season.
• Paying today's price for fixes that won't be done until 2027 or later.
• Assuming Measure B would raise your property tax bill. It is a sales tax.
• Using countywide numbers to judge a South Bay home. Imperial Beach's price-cut share (33.9%) is far above the county's (20.4%).

Quick checklist

• Address mapped against the river valley, Saturn Boulevard and the AIRE area
• FEMA flood zone checked and Natural Hazard Disclosure ordered early
• Neighborhood visited morning, evening and (if possible) after rain
• H2S dashboard and alerts reviewed for the nearest monitor
• Beach closure status checked on sdbeachinfo.com
• Transfer Disclosure Statement item 11 and flood items reviewed, follow-ups in writing
• Homeowners and flood insurance quotes in hand before contingencies are removed
• Inspection covering drainage, water intrusion, HVAC filtration and sealing
• Full monthly budget with insurance and filters included
• Offer price based on today's conditions and the listing's market time

What this means day to day

Living near the Tijuana River today can mean smelling sewage on some mornings, running air purifiers, checking a beach closure map before a surf session, and paying attention to rain forecasts this winter. Plenty of families in Imperial Beach, Nestor and San Ysidro love their neighborhoods anyway: the ocean breeze on good days, the small-town feel, and prices well below most of the San Diego coast. The key is to go in with clear eyes. Buyers who check the air, water and flood data, budget for insurance and filtration, and negotiate on today's conditions can find real value in South County. Buyers who skip those steps may end up with a home that's harder to enjoy, and harder to sell, than they expected. If the river cleanup succeeds on the timeline officials describe, owners who bought carefully will benefit, but that's a bonus, not a guarantee.

If you're thinking about buying in Imperial Beach, Coronado, Chula Vista, San Ysidro or anywhere in South County, Choice of America can help you check disclosures, flood zones and insurance, and negotiate a fair price. Call or text 833-THIS-BROKER (833-842-7465), visit Choice of America, or see our San Diego County real estate page.

Dr. Hamid Rowshan, Choice of America. DRE #02004794. Company DRE #02240008.

This article is general information, not legal, medical, tax, lending or insurance advice. Health questions about hydrogen sulfide or sewage exposure should go to a doctor or the County of San Diego. Conditions, timelines, rates and rules change; confirm current information with SDAPCD, the County of San Diego, FEMA, your lender, your insurer and a real estate attorney before you buy.

Sources:

• Realtor.com Residential Data, county core metrics (September 2026): https://econdata.s3-us-west-2.amazonaws.com/Reports/Core/RDC_Inventory_Core_Metrics_County.csv
• Realtor.com Residential Data, ZIP core metrics (September 2026): https://econdata.s3-us-west-2.amazonaws.com/Reports/Core/RDC_Inventory_Core_Metrics_Zip.csv
• Freddie Mac Primary Mortgage Market Survey via FRED, MORTGAGE30US (7.32% on Oct 22, 2026): https://fred.stlouisfed.org/series/MORTGAGE30US
• Times of San Diego, "County appoints veteran diplomat to lead response to Tijuana River pollution crisis" (Oct 19, 2026): https://timesofsandiego.com/environment/2026/10/19/san-diego-county-veteran-diplomat-tijuana-river-pollution/
• CalMatters, "San Diego County approves first step toward billion dollar plan to stop Tijuana sewage pollution" (Sep 1, 2026): https://calmatters.org/environment/2026/09/tijuana-river-pollution/
• Times of San Diego / City News Service, "Imperial Beach coastline closed over sewage contamination" (Sep 27, 2026): https://timesofsandiego.com/environment/2026/09/27/imperial-beach-coastline-closed-over-sewage-contamination/
• UCSD Guardian, "San Diego County issues beach closures and advisories amid sewage contamination" (Oct 5, 2026): https://ucsdguardian.org/2026/10/05/san-diego-county-issues-beach-closures-and-advisories-amid-sewage-contamination/
• U.S. EPA, Tijuana Sewage Crisis Quarterly Update (Sep 30, 2026): https://www.epa.gov/newsreleases/trump-epa-tijuana-sewage-crisis-quarterly-update-phase-2-river-gates-under
• U.S. EPA, Tijuana River Watershed Public Updates: https://www.epa.gov/sustainable-water-infrastructure/tijuana-river-watershed-public-updates
• County of San Diego Registrar of Voters, Resolution 26-097 and Measure B text (Nov 3, 2026 election): https://www.sdvote.com/content/dam/rov/en/election/nov-3-2026-gubernatorial-general-election/san-diego-county-fund-health-and-safety-services.pdf
• Ballotpedia, San Diego County Measure B (November 2026): https://ballotpedia.org/San_Diego_County,_California,_Measure_B,_Issue_Sales_Tax_to_Fund_Health,_Family,_Environmental_Protection,_and_Public_Safety_Services_Initiative_(November_2026)
• San Diego County Air Pollution Control District, Tijuana River Valley: https://www.sdapcd.org/content/sdapcd/about/tj-river-valley.html
• SDAPCD, Hydrogen Sulfide Monitoring and Community Hydrogen Sulfide Guidance: https://www.sdapcd.org/content/sdapcd/about/tj-river-valley/tjrv-air-quality-monitoring.html
• SDAPCD, Air Improvement Relief Effort (AIRE) Program: https://www.sdapcd.org/AIRE.html
• County of San Diego DEHQ, Beach and Bay Water Quality (closures and advisories): https://www.sdbeachinfo.com/
• NOAA Climate Prediction Center, ENSO Diagnostic Discussion: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml
• NOAA Climate Prediction Center, Long-Lead Seasonal Outlook discussion (Oct 15, 2026): https://www.cpc.ncep.noaa.gov/products/predictions/long_range/lead14/fxus05.html
• FEMA Flood Map Service Center: https://msc.fema.gov/portal/home
• FloodSmart (NFIP), What's covered and waiting periods: https://www.floodsmart.gov/whats-covered
• FloodSmart (NFIP), Flood insurance cost and elevation certificates: https://www.floodsmart.gov/flood-insurance-cost
• FloodSmart (NFIP), What is my flood risk: https://www.floodsmart.gov/flood-zones-and-maps/what-is-my-flood-risk
• HelpWithMyMortgage.gov (OCC), Can the bank force me to buy flood insurance?: https://helpwithmymortgage.gov/help-topics/mortgages-home-equity/flood-insurance/flood-required.html
• California Civil Code 1103.2, Natural Hazard Disclosure Statement: https://california.public.law/codes/civil_code_section_1103.2
• California Civil Code 1102.3, delivery of disclosures and right to terminate: https://california.public.law/codes/civil_code_section_1102.3
• California DRE, Real Estate Transfer Disclosure Statement (RE 6): https://www.dre.ca.gov/files/pdf/re6.pdf
• California Air Resources Board, Indoor air cleaners for removal of odors and gases: https://ww2.arb.ca.gov/indoor-air-cleaners-removal-odors-and-gases
• CARB clean air space infographic (via SDAPCD): https://www.sdapcd.org/content/dam/sdapcd/documents/tjrv/aire/CARB-CleanAirSpace-Infographic.pdf