In the Uluguru Mountains of Tanzania, an expansion in informal hosepipe irrigation by small-scale farmers
has enabled the development of horticulture, and resulted in improvements in farmers' livelihoods. This has
largely taken place independently of external support, and can be seen as an example of the 'private' irrigation
that is increasingly viewed as important for sub-Saharan Africa. However, these activities are seen by
representatives of government and some donors as the cause of environmental degradation and water
shortages downstream, especially in the nearby city of Morogoro. As a result, there have been attempts to
evict the farmers from the mountain. Negative narratives persist and the farmers on the mountainside are
portrayed as a problem to be 'solved.' This article explores these tensions, contributing to debates about the
formalization of water management arrangements and the place of the state in regulating and adjudicating
rights to access water. We argue that a focus on legality and formalization serves to obscure the political
nature of competing claims on resources that the case illustrates.