The Landscape

An entire connected landscape, still whole.

The reserve protects one of the largest remaining connected forest landscapes on the Nicoya Peninsula. Many of Costa Rica's protected areas have become isolated islands. This one still links the interior forests to the coast, and its headwaters supply drinking water to six communities.

Thirty years of independent monitoring show that protected forest produces measurably more water. Flow from a spring on land bought in 1997 rose from 8.87 to 16.32 litres per second. Twelve completed acquisitions show that donor support becomes permanent protection.

Mature and old-growth forest on the reserve boundary, seen from the air.

Water

Forests are the peninsula's water infrastructure.

The Nicoya Peninsula has become significantly drier over the past two decades. Longer dry seasons, rising temperatures and continued deforestation put growing pressure on local water supplies.

The forests in and around the Karen Mogensen Reserve absorb rainfall in the wet season and release it gradually throughout the year into the springs, streams and rivers that the region depends on.

Protecting the upper watersheds is one of the most effective natural responses available to a drying climate.

The Rio Blanco, an important river inside the reserve, fed by protected headwaters.

Three Decades of Proof

Protected forest produces more water.

Average water production of the El Paraiso springs, 1994 to 2025, in litres per second. Land purchased by ASEPALECO in 1997, monitored by the local water association since 1994. Source: ASADA Montana Grande de Isla Venado.

Twelve purchases, one reserve

Since 1996, ASEPALECO has acquired twelve properties, together protecting 1,005 hectares (2,483 acres) of tropical forest and critical watersheds. The most recent purchase, La Bruja, was completed in 2026 and appears on the map as number 12. It is already included in the total.

Each purchase has safeguarded forest, restored degraded land and expanded habitat for wildlife. Donor support becomes permanent conservation.

The twelve acquisitions that form the reserve today.

Watershed Protection

A conservation priority, headwater by headwater.

The proposed acquisitions extend protection to additional headwaters and forested catchments connected to the Rio Ario, Rio Blanco and Rio Bongo system. Preventing deforestation, fragmentation and incompatible development in these areas protects biodiversity, ecological connectivity and the long-term resilience of the water sources that existing communities depend on.

Watershed protection cannot rest on land purchases alone. It also depends on responsible spatial planning, sensible water-demand management and fair contributions from public authorities and commercial water users.

Micro-watersheds and ASADA water intake points across the reserve and its proposed expansion. Source: ASEPALECO, 2026.

The Communities

Six communities, and the people who defend the forest.

Six surrounding communities receive their drinking water from headwaters protected within the reserve. That dependence is also the reserve's strongest protection.

Two community water associations, ASADA Montana Grande and the ASADA in Rio Blanco, distribute that water to 783 registered households, for whom this single forested watershed is the only source. The reserve protects the headwaters of the Rio Ario and the Rio Blanco, which join to form the Rio Bongo closer to the coast, along with the rivers and aquifers that Cobano, Santa Teresa, Montezuma and other communities depend on.

ASEPALECO works with those communities through environmental education, a volunteer forest fire brigade and a community recycling centre. Land that neighbours understand and rely on stays protected long after a purchase is completed.

Educational camp at the reserve's Eco Lodge.

What Lives Here

One reserve, thousands of species.

Every hectare protected keeps this web of life intact. The same forest absorbs an estimated 10,000 tons of carbon dioxide each year.

Northern tamandua and red-eyed tree frog, both resident in the reserve.

Vermiculated screech owl. A very rare species, and the reserve is one of the most important places to find it.

Twenty-eight species, one closing window.

The reserve's vertebrate survey documents 28 species of amphibian, reptile, mammal and bird facing some level of extinction risk, either on the IUCN Global Red List or Costa Rica's national list. Every hectare of forest not protected is habitat one of them can lose.

Connection Matters

A sign of success, and a warning.

The recovering ecosystems of the reserve have produced a telling result: growing wildcat populations. Pumas, ocelots and jaguarundis now venture beyond the protected borders, clear evidence of successful breeding and a healthy environment.

Outside the reserve they meet farms instead of forest, come into conflict with the farmers whose livestock they take, and risk retaliation.

Fragmented forest strands species in patches too small to sustain them. The lasting answer is more connected, protected habitat, and that is what the expansion delivers.

Pumas, ocelots and jaguarundis share the same corridor, alongside many smaller species.

An Urgent Threat

The forest around the reserve is disappearing.

The land surrounding the Karen Mogensen Reserve faces several pressures at once, each of them accelerating.

• Real estate development. Developers clear forest for roads and housing, fragmenting habitat and cutting the corridors that wildlife depends on.
• Cattle farming. Pasture replaces native forest at scale, contaminating water and drying up the springs that feed the region.
• Plantation monoculture. Single-crop plantations degrade the soil, rely on heavy pesticide use and pollute shared water.
• Drying forest and fire. Declining moisture raises the risk and the intensity of wildfires across the whole ecosystem.
• Watershed loss. Deforestation dries the springs and rivers that wildlife and communities both rely on.
• Biodiversity collapse. Habitat destruction breaks connectivity and pushes more than fifty threatened species closer to extinction.

Former pastureland on the reserve boundary, part of Farm A, ready for reforestation.

Why now

The owner of Farm A is under family pressure to sell to private investors. Farm H has tripled in asking price within a single year. Government incentives for forest protection have been partly reversed, and the peninsula is developing fast.

Once forest becomes roads, housing or farmland, its ecological value is gone. Land protected now can still be protected whole. Land that is subdivided cannot be recovered.

The Master Plan

One corridor, two phases.

Farm A, left, and Farm B, right.

Protect. Restore. Connect.

These properties would expand forest connectivity, protect additional watersheds and restore degraded land. Today's pasture becomes tomorrow's forest.

Existing reserve in green, Phase 1 in dark blue, Phase 2 in light green.

Our Story

A legacy that started in 1955.

Karen Mogensen and her husband Nicolas Wessberg settled in Montezuma in 1955, when the Nicoya Peninsula was still largely covered in virgin forest. They watched it fall to cattle farming. By the early 1990s only 21% of the original forest remained.

The two became pioneers of Costa Rica's environmental movement. Their campaigning led to the creation of Cabo Blanco in 1963, the country's first protected nature reserve and the seed of the national park system the country is now known for. Karen died in 1994, shortly after the reserve that carries her name was established.

Nearly thirty years of dedication and donor contributions have since more than tripled its size, reversing deforestation hectare by hectare.

Karen Mogensen.

ASEPALECO

The Karen Mogensen Reserve is owned and managed by ASEPALECO, the Asociacion Ecologica de Paquera, Lepanto y Cobano, a Costa Rican non-profit environmental association founded in 1991. Its work spans land protection, environmental education in local schools, scientific research at the biological climate research station, and community engagement. ASEPALECO operates the Karen Mogensen Eco Lodge, maintains a volunteer forest fire brigade and runs a community recycling centre. It is governed by a volunteer board and partners with local communities, national agencies such as SINAC, and international organisations.

Those who have supported this work

• Robert Plant (Led Zeppelin)
• Provincia di Ferrara
• Nepenthes of Denmark
• The British Embassy
• The Dutch Embassy
• Impatto Zero
• LifeGate
• Foreste Per Sempre
• Ylang Ylang Resort
• Sano Banano Hotel
• The Tempisque Conservation Area of SINAC (ACT)
• The GEF Small Grants Programme (UNDP)
• Fundecooperacion
• ACTUAR Costa Rica
• Green Waves
• The Boston Foundation

And many other generous donors.