The Aliso Canyon natural gas storage facility sits in the hills above Porter Ranch. The 2015-2016 leak event triggered settlements, ongoing disclosure obligations, and a real but manageable diligence item for every buyer in the area. I'm Brian Cooper at eXp Realty (DRE# 01434286), and this page covers what the Aliso Canyon disclosure actually contains, what to ask during diligence, and how I've helped buyers work through it without abandoning the Porter Ranch search.
What Aliso Canyon is
The Aliso Canyon Storage Facility is one of the largest underground natural gas storage facilities in the United States, operated by SoCalGas. The site is located in the hills north of Porter Ranch, with the wellheads and surface infrastructure on a parcel approximately 1.5-2 miles from the nearest Porter Ranch residential parcels depending on the specific lot.
The facility uses depleted oil and gas reservoir formations to store natural gas at high pressure for delivery to the Southern California gas distribution network. The storage capacity is one of the largest in the western US.
The 2015-2016 leak
In October 2015, a wellhead at Aliso Canyon (SS-25) developed a leak that released natural gas (predominantly methane along with other hydrocarbons) into the atmosphere through February 2016. The leak triggered the relocation of thousands of Porter Ranch households during the active leak period, on SoCalGas's tab via a settlement program.
Government, regulatory, and litigation responses followed. The California Air Resources Board, the California Public Utilities Commission, the County of Los Angeles, and the City of Los Angeles all engaged in oversight and response. Civil litigation by affected residents was settled in significant aggregate amounts across multiple settlement programs.
What the buyer disclosure typically covers
Sellers in Porter Ranch typically include an Aliso Canyon disclosure in the transaction package. The disclosure addresses the historical leak event, the proximity of the storage facility, and whether the seller or prior owners participated in any settlement program.
The disclosure is a buyer-protection mechanism — it ensures the buyer enters the transaction knowing the material facts about the facility's proximity and the leak history. Read it carefully. Ask follow-up questions in writing if anything is unclear.
What to ask during diligence
Standard diligence questions go beyond reading the disclosure itself.
- Has the seller or any prior owner participated in any Aliso Canyon settlement program?
- How far is the specific parcel from the Aliso Canyon facility surface infrastructure?
- Are there any open litigation matters involving the property and Aliso Canyon?
- What is the current operating status of the facility (CPUC monitors this)?
- Are there any deed restrictions, easements, or settlement-program obligations attached to the parcel?
- What ongoing monitoring is in place?
- What does the seller know about indoor air-quality testing history at the property?
Ongoing facility status
Aliso Canyon remains operational under regulatory oversight as of May 2026. The CPUC has overseen ongoing monitoring requirements, pressure limitations, and well integrity programs. State legislative and regulatory activity around the facility's long-term future continues.
Buyers wanting current operational status should check the CPUC's Aliso Canyon proceedings page, the SoCalGas Aliso Canyon page, and current news coverage. Status changes over time.
How this affects the buying decision
Buyers approach the Aliso Canyon disclosure with varying tolerance. Some buyers proceed without concern after reading the disclosure and assessing distance and facility status. Some buyers want additional health or environmental review, including independent indoor air-quality testing during the inspection period.
Some buyers decide Porter Ranch isn't the right fit and route their search to adjacent ZIPs (Chatsworth, Granada Hills, Northridge) that don't carry the Aliso Canyon disclosure. All three responses are legitimate. The disclosure exists so buyers can make the call with full information.
What I tell buyers
I tell buyers three things. First, read the disclosure carefully and don't skim it. Second, ask the seller specific questions in writing during the inspection contingency period and get written answers. Third, consult appropriate professionals — environmental consultants for testing questions, attorneys for litigation questions, medical professionals for health-related questions. I'm not licensed to give those opinions.
I do tell buyers that the Porter Ranch market continues to clear with disclosed Aliso Canyon context. Homes sell, prices have continued to appreciate, and buyers continue to choose Porter Ranch on the strength of the master-planned community, Granada Hills Charter HS, and the housing product. The disclosure is a real diligence item, not a reason to abandon the search.
Settlement program context
Multiple settlement programs have run for Porter Ranch residents affected by the 2015-2016 leak event. Settlements have addressed property impacts, health-related claims, and other claim categories. Specific eligibility, claim periods, and program details have varied by program.
If the property's prior owner participated in a settlement program, the disclosure should reflect that. The buyer's purchase doesn't typically transfer prior-owner settlement rights but the property's history is material to the transaction.
Frequently Asked Questions
What is the Aliso Canyon disclosure?
The Aliso Canyon disclosure is a written disclosure included in Porter Ranch transaction packages addressing the SoCalGas Aliso Canyon natural gas storage facility, its proximity to Porter Ranch, the 2015-2016 leak event, and any seller or prior-owner participation in settlement programs. It's a buyer-protection mechanism ensuring buyers enter the transaction with material facts.
Is Aliso Canyon still operating?
Yes, Aliso Canyon remains operational under regulatory oversight as of May 2026. The CPUC has overseen ongoing monitoring requirements, pressure limitations, and well integrity programs. Operational status and regulatory framework have evolved over time — check current CPUC and SoCalGas sources for the most current state.
How far is Aliso Canyon from Porter Ranch homes?
The Aliso Canyon facility surface infrastructure is approximately 1.5-2 miles from the nearest Porter Ranch residential parcels depending on the specific lot. The distance varies by tract — northern hillside parcels closer than southern flat parcels. Verify the specific distance for the parcel you're considering.
Did the 2015 leak affect property values?
Property values in Porter Ranch went through dislocation during and immediately after the active leak event. Subsequently, the market has recovered and continued to appreciate. May 2026 medians are at or above prior peaks. The disclosure history remains a diligence item buyers and sellers address explicitly.
Should I avoid Porter Ranch because of Aliso Canyon?
That's a personal decision based on your own assessment of the disclosure, the current operational status, the distance to the facility, and your risk tolerance. Some buyers proceed; some choose to route their search to adjacent ZIPs (Chatsworth 91311, Granada Hills 91344, Northridge 91325). Both responses are legitimate.
Should I get independent air-quality testing?
Some buyers do — typically during the inspection contingency period. Independent indoor air-quality testing is a buyer-paid third-party service. Cost varies by scope. I'm not licensed to recommend specific testing protocols; consult an environmental consultant for guidance on what testing makes sense for your situation.
Does the disclosure mean the property is unsafe?
No. The disclosure is a transparency mechanism, not a safety determination. It ensures the buyer knows about the facility's proximity and the historical leak event. Safety determinations require professional input from environmental consultants, medical professionals, and regulatory bodies. I'm a REALTOR, not an environmental or medical professional.
