Surface Water and Watersheds

Watershed Management Program

In his 1998 State of the Union Address, President Clinton announced a major new national Clean Water Initiative, the Clean Water Action Plan (CWAP). This initiative aims to achieve clean waters by encouraging federal and nonfederal agencies, other organizations and interested citizens to work in a collaborative manner to restore our highest priority watersheds. The federal government has committed to contributing its technical and financial resources to the implementation of the plan. Guam responded to this federal initiative by convening a work group, the Water Planning Committee (WPC), which is made up of representatives from fourteen agencies and interested organizations. The WPC completed an assessment of the island´s watersheds and selected three, the Northern, Ugum and Talofofo, as its highest priority watersheds due to their value as drinking water resources.

In 1987, the Pohnpei state legislature passed the Pohnpei Watershed Forest Reserve and Mangrove Protection Act in which close to 5,000 hectares (or 12,500 acres) of upland forest was set aside as a protected Watershed Forest Reserve. The purpose of this act was to halt the degradation of the interior forests from road construction and population encroachment as well as to protect the watershed and water supply for the island´s population. However, when surveyors attempted to mark the boundary of this reserve, suspicious and angry villagers with machetes and guns turned them back. With this single act, the story of watershed management on Pohnpei began and continues to unfold today.

WERI researchers have undertaken several projects for developing a watershed management strategy for Guam and the Federated States of Micronesia. In Guam, researchers assessed the existing natural resources of the Ugum watershed and identified the areas that have potential to contribute pollution into the streams and eventually into the coastal areas within the Ugum.

In Pohnpei island researchers are developing a data base for three watersheds with different degree of man´s activities. Data includes rainfall, stream flow, turbidity, land clearing for agriculture, road construction, and housing development. The overall objective of this project is to study the impact of man´s activities on the quality of the water in the watershed and make recommendations to reduce the impact of these activities.

Soil Erosion Monitoring Programs

Surface runoff and sediment losses from soil erosion are major contributors to reduction in surface water quality and subsequent degradation of the coral reefs in Guam and the other islands in Western Pacific. The Guam Waterworks Authority (GWA) is presently pumping an average of 2.4 million gallons per day from Ugum River in Southern Guam to the potable water treatment facility. GWA faces an difficult task to keep the plant operating at full capacity when the river is running with high turbidity rates due to heavy rainfall because of permit limitations. This highly turbid water has increased operational costs and along with former poor operation and maintenance practices that led to premature failure of components of the treatment plant system. Most of the Operations Maintenance issue have been resolved but the operating permit still limits GWA’s allowed operating parameters because of unresolved issues with its operating permit. The water that passes the Ugum treatment plant intakes eventually makes its way to the outlet of the river and into the estuary and reef environment. The negative impact of sediment loading tends to result from sporting and hunting activities by people in the Ugum watershed. This in turn has a negative impact on the aquatic environment of Guam in the degradation of coral reef, as well as reduction of fish populations and impediment of the scenery affecting the tourism industry.

WERI researchers have undertaken projects aiming at various methods for estimating upland soil erosion and soil conservation practices. In a project funded by the National Oceanic and Atmospheric Administration (NOAA), WERI researchers developed a GIS based erosion model for the Ugum Watershed. This model, which integrates the Universal Soil Loss Equation (USLE) with the ESRI GIS software package, predicts the soil erosion potential within a watershed and also identifies the areas with highest soil erosion potential. The model is currently used to explore various soil erosion practices with their accompanying costs to determine the optimum erosion control practice that is most effective in reducing soil losses and is most cost effective.

Rooftop Rain Catchment Sizing

WERI Online Publication: 
Designing Your Rainwater Catchment and Storage System 

The two major sources of water supply in the atoll islands and many rural areas of the high islands of the Federated States of Micronesia (F.S.M.) are rooftop rainfall catchment systems (RRCS) and shallow groundwater sources. The rain catchment systems are best suited for supplying drinking water needs. Other water demands are best met from groundwater sources. An ideal water supply system would have the components of the RRCS and the groundwater components sized in such a manner to meet the needs of the individual family that owns the system.

This project, which was funded by the US. Geological Survey Water Institute Program, was designed to develop and disseminate criteria to be used in the design of new or refurbishing of existing individual water supply systems for various islands in the F.S.M. The end product was a design brochure for sizing combined rooftop rain catchment systems so that they can provide a continuous water supply even during drought conditions.

A Windows based computer simulation model was developed to evaluate the effectiveness of various RRCS configurations for varied use rates. The next phase of the study involved an inventory of use rates, catchment sizes and tank configurations for various island groups in the Federated States of Micronesia. This was used to update and verify past studies which have been made concerning water consumption in Micronesia. Rainfall data and use rates served as input to the RRCS model. Output from the model was used to develop a set of design tables to be used by island sanitarians and residents in planning the design of new or the upgrading of existing RRCS systems. A brochure containing these tables has been printed and is being distributed to Island residents in the Federated States of Micronesia. Several workshops have been held in F.S.M. so that local sanitarians and water resources planning personel can take full advantage of the brochure and computer program.

This first study developed guidelines for all the islands of Yap, State F.S.M. and all the islands of Namonweito Atoll and the Pattiw area of Chuuk State F.S.M. Other studies are presently being planned for Saipan in the Commonwealth of the Nothern Mariana’s Islands, Pohnpei Island and Majuro and Kwajalein atolls in the Republic of the Marshall Islands.