You might also check out Onset Hobo data loggers. The old versions several decades ago were very inexpensive, and needed to be contained in a water proof capsule.  To save funds, extra protection was added with plastic whirl-pak bags as very inexpensive. The new data loggers are likely better and more expensive, and some issues with people finding and damaging, so se started to include a note on who to contact, what the temperature recorders were doing to help identifymand improve fish habitat.  I have had good results with them (Hobos) as long as not damaged,,stolen or taking on water.  The technology has improved in the last 20 years.  I have not used Tinytag, but in an earlier researchgate question, some individuals found them reliable.  I made sure we secured them in sections of plastic pipe that were cabled to strong roots or other relatively immovable oblects, hand burying cable under rocks if available to obscure detection.  It is important to provide map and description of location if the person installing will not be servicing the data loggers, perhaps even capture a picture of site.  If stream is likely to be intermittent, you may want to locate in pool, but I usually preferred sections with more velocity to avoid sediment burial if evident.

Thanks for your answer.

Yes, I use Onset. But main disadvantage for me is only factory replacement of battery. So I'm trying to find another solution.

The hobos are great if the resolution suits your needs. We found that the temp resolution was too low for the cave systems we were working in so we started building our own underwater data loggers: http://www.mdpi.com/1424-8220/18/2/530

The black rubber bottomed model is water tight to ~4m, and you can add whatever sensors you wish to use. Perhaps more interestingly, most I2C light sensors have threshold alarms, so you can have the logger only take readings when the light reaches a certain level..