The research of the draining surface water from drained areas has become relevant with an increase of drainage system areas. In order to maintain sufficient drainage efficiency by the draining surface water from the drained fields the density of open inlets for the surface water had to be increased to 5.5 u 100 haE-1. That was determined by the density decline of the open ditches. The observations of the technical condition of open inlets for the surface water in the drained fields of the country have been performed since 1986. It was established that prevalent type of the inlets is F-5 design. Such inlets amounts over 90% of all tested ones. The article discusses the condition of the inlets of such type, evaluates the selection of the installation location, conditions of surface water running to an inlet and the condition of water inlet openings. The research demonstrated some disadvantages of inlet designs, quite a few mistakes of installation and breakdowns during operation. A clear increasing tendency of water inlet openings being blocked by the ground and vegetation was established: in 1986 11.1% of water inlet openings were completely blocked, in 1996 the percentage was 20.8% and in 2007 it was 42.9%. On the basis of this it can be stated that the inlets with halfway blocked openings will stop functioning soon as well if the maintenance work is not carried out in good time and an appropriate way.

Both forestry theory and practice have proved that amelioration favours the growth of forest stands significantly. The growing stock increases even 10 times, if the amelioration system is well-functioning. Joint Stock Company Latvia State Forests that is managing half of forests in Latvia has started renovation of old amelioration systems aiming to improve the productivity of state owned forests in Latvia. In order to evaluate the impact of the renovation of the old amelioration systems, a tree ring width in 7 pine stands, 5 spruce stands and 3 birch stands was analysed. This study shows that the renovation itself has not affected the productivity of mature pine, spruce and birch significantly 3-4 years after the renovation. Authors have come to a conclusion that the reason for that could be too short observation period or particularities of a stand structure and age.

The establishment, maintenance and renovation of forest drainage systems are carried out to ensure the development of high quality forest stands and to secure access to forest resources, but it also poses a risk of erosion and increased discharge of suspended solids and nutrients associated with it. The aim of the study was to analyse the efficiency of standard-sized sedimentation ponds built by JSC ‘Latvia’s State Forests’ for sediment and nutrient retention during and after drainage network maintenance. To assess the efficiency of standard-sized sedimentation ponds six study sites were established and various chemical and physical parameters were measured for three years to evaluate water quality and to estimate runoff of plant nutrients and suspended solids. Sampling was carried out before and during drainage network maintenance and during two years following it. Despite the fact that some effect in reducing suspended solid export from catchments was observed, the results revealed insufficient efficiency of the sedimentation ponds in retaining plant nutrients and eroded matter during and after the drainage network maintenance. Retention of Ntot, N-NO3 sup(-) , P-PO4 sup(3-), N-NH4 sup(+) and DOC was ambiguous. It was concluded that other water protection structures should be considered or different parameters of sedimentation ponds should be used to improve the water quality exiting the drainage systems and entering waterbodies.

Basing on the economic, ecological and social points of view, the polder systems in the Nemunas lowland are considered as unique, requiring a great deal of annual state subsidies. According to the land-improvement programme, during the period of 2006-2008, Lithuanian polder system are planned to be yearly granted 2.15 million euro from the State budget, whereas the local administration of Silute district, which is exploiting the polders of the Lower Nemunas - more than half of the sum (63%). The article includes the analysis of exploitation expenses and statistical estimation of the Lower Nemunas' polders during the period of 1996-2006 as well as the investigation of the funds distribution on routine repairs, reconstruction and maintenance work. The average annual expenses on the pump stations, dikes, ditches and roads during the research period were determined. The analysis of the previous decade's expenses shows that the statistical average of the expenditure on the polder systems of Silute district amounts to 0.68+-0.13 million euro a year. The yearly renovation of polders depreciation should be obviously awarded a grant of the amount not less than 0.72 million euro.

Land reclamation is very important in Lithuania: under the climatic conditions of our country it is necessary to drain land. Today approximately 90% of the whole agricultural production are grown in drained land. In this article financial problems of land reclamation works are analysed. Not taking into account our country's financial abilities, the maintenance of land reclamation systems must be done properly, and in time - only then, we will be able to guarantee the best long-lasting functioning of drainage systems, and in the future there will be no greater and it will be unnecessary to do expensive preliminary reconstructions works. The maintenance works of drainage systems may be full-filled properly and in time when increasing the financing for land reclamation works up to the necessary level (any subsidies resources and payments are possible, as well as different labour variants and other alternatives) or reducing the maintained drained areas, so that we could throughly keep on eye on land reclamation systems.