World Solve

freshwater becoming salty remains one of the most urgent challenges of our time. Systems currently in place are inadequate for the scale and complexity of the problem. A successful approach must work where resources are scarcest and demonstrate clear, measurable results. It should identify possible harms, respect local agency, and show how the solution can be maintained and expanded by the communities it is meant to serve.

Melting Himalayan glaciers, overextraction, and pollution are shrinking freshwater availability faster than population growth. Efficient irrigation technology and river-basin cooperation agreements are urgently needed.

Treated wastewater is rarely reused for non-potable purposes despite growing water stress in many urban areas. Decentralized greywater recycling systems for buildings could meaningfully cut freshwater demand.

Rapid expansion of fish farming to meet protein demand has led to water pollution and frequent disease die-offs that hurt small farmers. Better aquaculture management training and disease-monitoring tools could improve sustainability.

Rising sea levels submerge shallow freshwater lenses beneath coral atolls, forcing island communities to rely entirely on variable rainwater harvesting.

Inland freshwater fishermen lose significant portions of their daily catch due to lack of localized ice plants and affordable off-grid refrigeration.

Fertilizer runoff from farms feeds harmful algae blooms in nearby lakes, damaging drinking water and local ecosystems. Preventing this at the source remains cheaper than treating it after the fact, but adoption is still limited.

Fertilizer and pesticide runoff from farms create dead zones in rivers and lakes where oxygen levels drop too low to support aquatic life. Preventing this runoff without harming farm productivity remains an unresolved environmental challenge.

Salt and chemicals used to keep roads safe in winter can wash into nearby streams and lakes, harming aquatic life over time. Finding equally effective but less harmful alternatives remains an underaddressed environmental challenge.

Dams provide clean energy and water management benefits but can block the migration routes that many freshwater fish species depend on to reproduce. Designing infrastructure that serves both human and ecological needs remains an unresolved engineering challenge.

Freshwater mussels play an important role in filtering water and supporting aquatic ecosystems, but they're highly sensitive to pollution and warming, and many populations are declining as a result. Protecting this often overlooked species remains an unresolved conservation issue.

Coastal aquifers in Fiji are increasingly contaminated by saltwater intrusion driven by overextraction and rising sea levels, threatening long-term drinking water and irrigation supply.

Develop integrated fisheries, water-flow, pollution, invasive-species, and habitat strategies for ecosystems supporting millions of people.

Create water, waste, energy, land-use, and visitor-management systems that support residents as climate stress and seasonal tourism intensify.

Establish practical measurement methods and interventions for microplastics moving from rivers and sediments into fish, crops, livestock, and human diets.