Since this is something new, unless you have had unusually heavy rains or snowmelt recently, I would look first for water accumulating agaisnt the foundation - from snow drifts, rainfall not draining away from the house, or maybe blocked gutters dumping water there.
Could also be a blocked french drain - Sewer Cleaning company can bring drain cleaning tools and camera to run through there and clean it out (jetting equiment best for this use) and see if there is a blockage or something.
It is also possible, especially if you do not have an exterior french drain, that the waterproofing on the house (usually asphaltic spray (with or without a stick-on asphaltic felt mat over it, or peel-and-stick plastic type) had gotten old enough that water is getting through it. VERY few contractors put waterstops at the strip footer/foundation wall interface, so that is a common place for seepage to start.
And of course, it may be the tree roots have gotten through the waterproofing - either breaking it up so water comes in, or actually starting to break up the foundation joints.
Here is a recent similar question about leakage (though theirs is at ground level with a slab-on-grade), but it discussed surface drainage to keep water from accumulating near the foundation. Works in most cases, but of course not in ones where the groundwater level is higher than your foundation slab - though if that is the case you would have frequent sump pump operation.
https://answers.angieslist.com/Lookin...
You can find a LOT of other previous questions with checklists and suggestions about remedying basement water infiltration issues - almost always remedying the situation OUTSIDE the house, and preferably before the water gets against the foundation, is the best solution. Check them out in the Home > Basement Waterproofing link, under Browse Projects, at lower left.
