Learn more about CZM INFRASTRUCTURE CAPACITY BUILDING

About Manell-Geus Watershed

The Manell-Geus Watershed in Malesso’, Guam is a critical coastal ecosystem locally that plays a vital role in maintaining coral reef health and marine biodiversity. This watershed spans over 4,000 acres and encompasses Achang Reef Flat Preserve, one of Guam’s five locally managed Marine Protected Areas (MPAs) and represents 10.1% of the island’s MPA network. It also encompasses Cocos Lagoon, the island’s only shallow water lagoon and natural barrier reef system that is home to soft coral strands. 

Despite its ecological importance, coral ecologists have identified sedimentation from eroding river banks, extensive badlands, and sparsely vegetated areas as a major cause of reef degradation in the Manell-Geus Watershed and around southern Guam.

This project improves water quality and coral reef health through stormwater management at high-traffic public areas within the watershed. This will be done by installing bioretention basins and a native rain garden to filter and direct runoff before reaching nearshore waters.

These solutions enhance habitat conditions for coral reefs, and coastal ecosystems, benefiting both marine and terrestrial Endangered Species Act (ESA) species. Ongoing water quality issues threaten reef resiliency, biodiversity, and public health.

With increasing population, development, storms, and rainfall, nature-based solutions and green stormwater infrastructure are urgently needed to mitigate degradation.

Project Outcome(s):

• Improved water quality targets: Reduction in enterococci bacteria levels and sediment loads at key monitoring sites, particularly in the Malesso’ Pier – Mama’on Channel to support meeting Guam’s water quality standards monitored by Guam Environmental Protection Agency and establishing water quality targets for neighboring watersheds.
  
  
• Site-specific watershed restoration to reduce land-based pollution inputs and improve stormwater management: Implementation of 3 priority green infrastructure solutions/low-infrastructure to manage runoff, decrease sedimentation and pollutant loads from entering nearshore waters through targeted nature-based solutions, and improve stormwater retention capacity.
  
  
• Healthy and resilient coral reef systems: Improved coral reef health by reduced sediment and pollution loads, further improving conditions for coral resiliency for current and future generations.
  
  
• Increase in coral reef monitoring: In-water marine surveillance with snorkel activities to survey and collect in-water data.
  
  
• Improved community engagement.
  
  
• Increase capacity building.
  
  
• Improve barriers & obstacles of green infrastructure in Guam.
  
  
• Increased compliance and partnerships.

Project partners

• Guam Environmental Protection Agency
• Guam Department of Agriculture
• University of Guam Center for Island Sustainability and Sea Grant
• Malesso’ Mayor’s Office
• The community of Malesso’