Paper presents theoretical background of „Programme of water retention increase in Mazowieckie Voivodship”. Special attention was paid on area evaluation and proposal of investments order. Evaluation of the voivodship area was focused on classification of regions, where increase of water retention is of high priority, average priority or Iow priority. Order of investments (construction or modernization) was based on evaluation results, but included additionally other factors as water Ä…uality, presence of protected areas, streams continuity maintaining, etc. Paper includes also guidelines for program implementation. ...