Since July 2, 2026, Lake Arenal's legal edge has been a fixed elevation of 548.58 meters above sea level. In the past twenty years the reservoir has never risen that high. The law, published that day in La Gaceta as Law 10.963, measures every lakefront setback from that contour. Anyone who walks a parcel near Tilarán or Nuevo Arenal and paces back from the water to find the protected strip is starting from the wrong place. The rules that will decide what can be built inside that strip are not due for up to two years.
The legal edge sits higher than the water has reached in twenty years
Article 1 of the law creates the Área Silvestre Protegida Paisaje Nacional Espejo de Agua Embalse Arenal. It covers the reservoir's surface up to the 548.58-meter contour, including the islands. Article 2 assigns the job of marking that contour on the ground to the Instituto Geográfico Nacional, working with ICE and MINAE. Article 7 adds a sustainable-use buffer zone of 50 meters, "measured horizontally" from that contour.
Now compare that number with how the reservoir actually runs. ICE says Arenal operates between 529 and 546 meters. In January 2025, after one of the wettest Decembers in records going back to 1958, the lake reached 546.87 meters. ICE called that its highest level in 20 years, the previous peak being 546.78 meters in 2005. At the other end, La Nación reported the lake at 539.11 meters on October 26, 2024.
| Reference point | Elevation | Distance below the legal contour |
|---|---|---|
| Legal contour, Law 10.963 | 548.58 m | n/a |
| 20-year high, January 2025 | 546.87 m | 1.71 m |
| Top of ICE operating range | 546 m | 2.58 m |
| Reported level, October 26, 2024 | 539.11 m | 9.47 m |
| Bottom of ICE operating range | 529 m | 19.58 m |
Those gaps are vertical. How they translate into ground depends on how steep each parcel is. On a steep bank, a couple of meters of elevation might mean a short walk uphill from the water. On a gentle slope, the same rise can cover a wide band of grass that has stayed dry for decades. Either way, the buffer starts at the contour, and the 50 meters run inland from there. Two lots that look the same from the dock can lose very different amounts of land to the legal strip, and only a survey against the official contour shows which is which.
What the strip was before July, and what it became
Under the old rule, Article 33 of the Forest Law set a 50-meter horizontal protection zone around natural lakes and around reservoirs built by the State or its institutions. Private artificial lakes were exempt. Arenal is ICE's reservoir, set aside as a national energy reserve by Law 4334 of 1969, so the rule applied around the whole shore.
Over time, makeshift docks, fishing and tour operators grew up along that protected shoreline anyway. La Voz de Guanacaste reported that Canatur's Tadeo Francisco Morales estimated about 100 small businesses were operating around the lake without a clear legal footing. Morales also argued that not all land around the lake was properly expropriated when the reservoir was filled in the 1970s, so the water covered private property. That is his account, offered in support of the law, and it is not a finding that applies to every parcel. Tilarán Mayor Katherine Alfaro López put the number of affected families at about 700. She said many faced legal proceedings that barred them from building on or using their land.
Article 8 of the new law lifts the Forest Law protection inside the 50-meter buffer, except in areas with intact forest cover and in environmentally fragile areas. On the water, Article 4 lists uses that can be authorized: subsistence, sport and tourist fishing, aquaculture, water recreation, water transport, low-impact tourism infrastructure, and tourist docks under Law 7744. The legislature passed it unanimously, first on May 28 and then in second debate on June 2, 2026.
"For everyone in Tilarán, for the whole region around Lake Arenal, this project will mark a before and after in the history of economic development." Mayor Katherine Alfaro López, speaking to Guanacaste a la Altura in March 2026
Permission now comes in layers, and ICE sits in every one
The law does not hand anyone a building permit. Article 10 requires any activity in the protected water area to fit the management plan. It must also carry a municipal authorization under the buffer-zone plan and a SINAC authorization for the water itself. Tourism businesses need an ICT declaratoria turística, and fishing and aquaculture fall under the Fisheries Law. Tourist docks need a concession that ICE grants, and every activity needs ICE's approval.
On land, Article 11 lets ICE's board grant concessions to use its own property in the buffer zone and on adjoining land, on terms ICE sets. If a concession is canceled for a breach, including a transfer or mortgage without ICE's consent, the buildings become ICE property. If ICE takes a concession back in the public interest, the holder is paid for buildings and improvements at an appraisal set by experts that the Dirección General de Tributación appoints.
For a buyer, the practical point is that a lakeside parcel can now be held in one of two ways. Some parcels are titled private land whose buffer portion becomes usable once the plan is in place. Others are, or sit next to, ICE land, where any right to use the strip would come through a concession that ICE can cancel and that can't be pledged as collateral without ICE's approval. The two can look the same on a listing sheet and work very differently at a bank.
The rules that make the strip usable are still being written
The law has been in force since publication. The documents that will actually govern land use come later, on these timelines:
| Instrument | Who produces it | Deadline in the law | Date, counting from July 2, 2026 |
|---|---|---|---|
| Implementing regulations | Executive branch | 6 months | around early January 2027 |
| Plan General de Manejo for the water area | SINAC, with ICE, Incopesca, municipalities and others | 2 years | around July 2028 |
| Plan de Desarrollo Ambiental y Social for the buffer zone | Approved by ICE, with municipalities, MINAE and Cidecat | 2 years | around July 2028 |
| Existing activities brought into compliance | Operators | Up to 24 months after the management plan takes effect | could run to 2030 |
The law defines the PDAS as the instrument that sets land uses, zoning, densities and access to the water in the buffer zone. Until it exists, nobody can say how much can be built in the strip, or where. As of early October 2026, our research found no published regulations, draft regulations or court action on the law. That is a gap in what has been made public, and it does not prove nothing is moving. Permits issued before the law stay valid until they expire. Any that expire before the regulations are issued remain valid until the new rules are in place.
Why the gap matters to price
The law changed the lakefront question from whether land near the water can be used to how much and under what terms. The answer to that second question is in documents due in 2028. A buyer who pays today for future buffer-zone use is paying ahead of the rules. The value depends on zoning densities, forest-cover calls and ICE concession terms that have not been set.
There are open questions about how the law will be applied. Former Frente Amplio legislator Priscilla Vindas criticized lifting protection on the same 50-meter strip the new area is meant to buffer. She noted that the law does not spell out how "environmentally fragile" areas will be identified. Legislator Edgardo Araya urged colleagues to request a Constitutional Court review over technical studies he said were missing. Our research did not locate a filed request or a ruling. When La Voz asked about carrying-capacity or environmental impact studies, both Canatur and the mayor said those would come in the management plans and regulations written after the law passed.
Institutional backing is broad. The municipalities of Tilarán and San Carlos, the Intendencia de Peñas Blancas, CATURGUA, Canatur, and the chambers of commerce and tourism in Tilarán, El Castillo, Arenal–La Fortuna, Monteverde and the Zona Norte all supported the bill. CATURGUA's executive director, Rebeca Álvarez, argued that the lack of a law was the real risk because it prevented oversight of activities already happening on the reservoir. That backing makes it likely the plans will move forward. It does not tell you what they will allow on a specific slope.
What to put on the due diligence list
This list is for your own attorney and surveyor. It describes what the law requires and is not legal advice.
- Plot the plano catastrado against 548.58 meters. Ask a surveyor where the contour falls on the parcel and where the 50-meter buffer ends. IGN has not yet published its official delimitation, so treat any line as provisional until it does.
- Read the finca's history. Check whether any part of the parcel was ever ICE land or passed through an expropriation. That history shapes whether the strip is titled land or a likely concession.
- Identify title versus concession. If use of the strip depends on an ICE concession, read the cancellation, transfer and mortgage rules in Articles 12 to 15 before pricing it as owned land.
- List every existing permit and its expiry date. Under the transitional rule, those permits are the only certainty a current operation has until the new regulations arrive.
- Walk the forest cover. Intact forest and environmentally fragile areas keep their Forest Law protection inside the buffer.
- Treat any dock as a separate asset. A tourist dock needs an ICE concession under Law 7744 and ICE approval, no matter what the land title says.
Frequently Asked Questions
Does the 50-meter buffer start at today's waterline? No. Article 7 measures it horizontally from the 548.58-meter contour. ICE's normal operating ceiling of 546 meters is below that contour, and so was the January 2025 peak of 546.87 meters.
Can I build in the buffer zone now that the Forest Law protection is lifted? The law allows maintenance and minor works, plus structures that complement uses the PDAS authorizes. The PDAS is due within two years of July 2, 2026, and municipal authorization runs through it.
Has the law been challenged in court? Legislator Edgardo Araya urged his colleagues to request a Constitutional Court review. As of early October 2026, our research found no filed request and no ruling.
Lakefront parcels around Arenal will take survey work, a close look at title history and patience with a rulebook that is still being drafted. If you're weighing land near Tilarán, Nuevo Arenal or the Route 142 shoreline, our advisors at Engel & Völkers Costa Rica can bring the right surveyor and legal team in early. Connect with our Sámara shop to start.
