authorities begin to develop a program to monitor and analyze water quality parameters in areas at risk e.g. ports, rivers in agricultural zones, key estuaries.
A country environmental report finds that agrochemicals could be better controlled by both the Ministry of Agriculture and SEMARN through proper incentives and regulations World
Bank, 2004. Recommended measures include: ending subsidized credit for agrochemicals; ii enforcing prohibitions on internationally banned agrochemicals; iii licensing dealers and various
classes of applicators; and iv developing an information campaign and public awareness program that educates farmers on the proper use of agrochemicals.
6.3 Assessment of the Impact of Dams on the Yuna River Flow Regime
Across a period of record for a stream gage, natural variations in climatic conditions— especially the timing and amounts of rainfall in a region—have a substantial impact on a river’s
flow regime. These differences can manifest as variations in the overall volume of water discharged by the river during the year; the size, time of year, and duration of floods or low flow
conditions; and the frequency of these types of flow conditions within or across years. A number of human activities can change one or more of these natural characteristics of a river’s flow
regime, including land use conversion, construction and operation of dams, and ground water pumping or direct surface water diversions.
Using pre- and post-dam gauging data, we assessed the influence of the Rincón and Hatillo dams on the Yuna’s flow regime and consequently the freshwater inputs to Samana Bay
Appendix 2. The data illustrate that the post-dam period has been generally wetter than the pre- dam period, with consistently greater average monthly flows. While flows between January and
March dry season roughly doubled over the pre-dam period, increases in flow during other months have been far less dramatic. However, overall the influences of the dams on freshwater
inputs to Samana Bay are not clearly discernable from these data and the higher levels of flow in
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the post-dam period could be the result of other causes such as ongoing changes in land use, irrigation or simply differences in climate across the two periods.
6.4 Changes to Freshwater Inflows: Proposed Construction of Dam at Piedra Gorda, Bonao
Rice production is dependent on a high level of agrochemicals, which eventually find their way to Samana Bay, and is also dependent on an extensive irrigation system. The size of the
irrigation system and its inefficiency has already been documented. IRG 2001 reports that the growth of irrigation over the past 20 years has reduced normal dry season water flows in the
Yuna watershed, affecting downstream freshwater habitats. One of the threats to freshwater inflows is an expansion of the existing system of
irrigation with the construction of another dam in the upper Yuna River. INDRHI’s original masterplan for the Yuna watershed from the 1970’s included plans for a dam in the upper Yuna
River at Piedra Gorda, Bonao. In April 2003, the administration of President Mejia’s reported it was concluding plans to start construction of a multipurpose hydroelectric dam at this location.
The dam proposed by INDHRI would be located below the confluence of the Yuna River and Blanco River, about 2 kilometers upstream from the town of Los Quemados.
There is concern that the Hatillo dam is not functioning adequately, since it overflows about three times a year. The new dam would provide water for industrial, municipal use and
irrigation, and would help avoid frequent floods in the important rice growing zones of the lower Yuna River. It would transfer a large amount of excess water that the Hatillo dam cannot store to
the dam at Rincón by tunnel and canal. The canal would provide an estimated average of 10.3 m
3
s flowing to Rincón dam about 20 km north. The President’s web page says that 525 m
3
of water per year would be diverted to the Rincón dam www.presidencia.gov.doinglesNoticias-
2003Abril accessed February 5, 2004. This would supply water to several major cities in the Cibao Bonao, San Francisco de Macoris, Moca, Salcedo, Tenares and Villa Tapia. It would
extend the area of irrigation provided by the Rincón dam by about 13,000 hectares along the
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Jima and Camú riverbanks and other farming zones in La Vega and San Francisco de Macorís. It would also allow the addition of another turbine with a 10 MW capacity at Rincón dam
providing an estimated annual 21 GWH CDE, www.hidroelectrica.gov.do accessed February 5, 2004.
There was concern that the dam would reduce the flow of water needed downstream. INDHRI was unable to counter this concern and provide communications and outreach to local
stakeholders. As a consequence the development proposal has been dropped for the moment.
6.5 Deforestation and Sedimentation
