Short answer. Yes, within limits. Article 645 lets you, as the owner of the land burdened by an aqueduct easement, close or fence it and even build over the aqueduct — provided you cause it no damage and do not make the necessary repairs and cleanings impossible. Your ownership continues; it is simply subject to the easement.
What the law says
The easement of aqueduct does not prevent the owner of the servient estate from closing or fencing it, or from building over the aqueduct in such manner as not to cause the latter any damage, or render necessary repairs and cleanings impossible.
Civil Code, Article 645 — The Servient Owner May Still Build. Read the full provision →
You still own the land
An easement does not strip you of ownership; it burdens your land for a specific use by someone else — here, the passage of water through an aqueduct. Article 645 confirms that your rights as owner of the burdened, or servient, estate continue alongside that burden. It states that the easement of aqueduct does not prevent the owner of the servient estate from closing or fencing it, or from building over the aqueduct. So the presence of the aqueduct does not freeze your land or forbid you from making ordinary use of it. You may enclose, fence and even build above the channel, keeping your land productive.
The two conditions you must respect
That freedom carries clear limits designed to protect the easement itself. Whatever you do must be in such manner as not to cause the latter any damage, and it must not render necessary repairs and cleanings impossible. In practice this means your fence or structure cannot obstruct the flow, harm the aqueduct, or seal it off so that it can never be maintained. The person entitled to the water must still be able to keep the channel working and get to it for cleaning and repair. Build in a way that leaves the aqueduct sound and accessible, and you stay within your rights; build in a way that chokes or buries it, and you do not.
Balancing two legitimate interests
The article strikes a deliberate balance. The dominant owner needs the water to keep flowing and needs to maintain the works that carry it; the servient owner needs to use his own land rather than leave a strip permanently idle. Article 645 accommodates both by allowing construction that coexists with the aqueduct instead of defeating it. It reflects the general spirit of easement law: the servitude is limited to what its purpose requires, and everything the burden does not actually need remains with the landowner to enjoy.
What the article does not authorise
This is permission to build compatibly, not to interfere with or extinguish the easement. It does not let you divert or cut off the water, damage the aqueduct, or block the access needed to repair and clean it — doing any of those exceeds what the article allows. It also does not resolve who bears the cost if your structure later complicates maintenance, or settle disputes over whether a particular fence or building actually causes damage; those turn on the facts of the works. And it addresses the aqueduct easement specifically, not every other servitude that might cross your land.