We can't tell you about a specific river or lake without more details but can share the general laws of tvilat keilim in river and lakes. Note however that women should not immerse there without detailed instructions from their Rav 1.
- a large lake, the sea or an ocean are kosher for tvilat keilim
- a smaller lake with spring water flowing in can be kosher if it hasn't rained recently and there is no concern of melted snow
- rivers sourced from springs can also be kosher but not if fed from melting snow - their rules are more complex and small details can be critical (e.g., the presence of a turbine upstream to produce electricity)
OU Kosher brings some general rules
The general rule is that spring water is acceptable for tevilah even
when flowing, while rainwater and melted snow is acceptable only when
stationary. In situations where there is a mixture of rainwater and
spring water, we follow the majority: if mostly rainwater, the water
must be stagnant, but if mostly spring water, the stream is acceptable
for tevilah even when flowing.
Large lakes (which are viewed as stationary bodies of water), [seas] and
oceans are kosher for tevilah at all times, even if it had recently
The water in most larger rivers is primarily sourced from springs,
although the rivers may swell noticeably in the rain season. But my
concern is more about mountain rivers, that flow only in the warmer
weather, and are fed from the melting snow at the mountains' peaks.
Melted snow has the same status as rainwater, that it is valid as a
mikvah only when static, but not when flowing. So, you cannot immerse
vessels in a mountain river.
See there as well as here for further details. And as always, check with your Rav for any practical ruling.
1. Practically, there are many issues which render immersing into a lake or river very delicate for women, and very often lead to non-kosher immersions. Examples are hatzitzot of earth while going down to the water, danger of currents, the fear of being seen which leads to being rushed and making mistakes, challenges of letting go of clothes, difficulties in checking the woman is ready for immersion or that it was done correctly, etc.