Short answer. If the river is navigable or floatable, the island belongs to the State, and the same is true of islands forming on lakes or on the seas within Philippine jurisdiction. Owning the bank gives you no claim to it. The character of the water is what decides the question.
What the law says
Islands which may be formed on the seas within the jurisdiction of the Philippines, on lakes, and on navigable or floatable rivers belong to the State.
Civil Code, Article 464 — Islands on Seas and Navigable Rivers. Read the full provision →
The rule and what it turns on
The provision is a single allocation: islands formed on the seas within the jurisdiction of the Philippines, on lakes, and on navigable or floatable rivers belong to the State. Nothing in it depends on who owns the bank, how close the island lies to one side, or how the island came to be. The operative fact is the character of the body of water. Waters of that description are not private property to begin with, and land that emerges within them is treated as public in origin rather than as an addition to somebody's parcel.
Navigable or floatable is the dividing line
The article does not say every river. It says navigable or floatable ones, which is a description of what the watercourse can carry rather than a label anyone applies casually. Rivers that fall outside that description are not covered by this rule, and islands forming in them are dealt with under a different provision that looks at the banks. So the whole answer for a particular island can turn on a factual question about the river — whether it is used or usable for the passage of vessels or the floating of goods — long before anyone reaches the land itself.
Why long occupation does not convert it
Riparian owners often assume that clearing, planting or fencing an island over many years turns it into theirs, especially where nobody objected. Property belonging to the State in this way is not acquired by simply staying on it, and improvements made on it do not change its character. What years of use can produce is a claim to be dealt with as an occupant, and sometimes an application under whatever scheme governs the disposition of public land of that kind — but that is a process with its own requirements, not a title that has quietly matured on its own.
What to establish before doing anything
Two questions come first, and they are both factual. What is the water — sea, lake, or river, and if a river, is it navigable or floatable? And is the land genuinely a new island, or is it the product of gradual deposit along your own bank, which is a different rule with a different owner? A dated survey, older maps or imagery showing the channel before the formation appeared, and your own title with its technical description are what a lawyer will want to see before advising you to build, plant or spend anything on it.
Cases citing this provision
These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.
- Octabela Alba Vda . de Raz, etc., et al. vs. Court of Appeals, et al, G.R. No. 120066, September 9, 1999 — read the decision on LawPhil →