The National Hydrography Dataset indicates an unlikely-seeming underground waterway splits off from Mill Slough at this point. Is there any on-site evidence for its existence?

In context of overlay "Addresses" – house number 727 – node/12606308571 via StreetComplete 60.1:

Detached house under construction

1471 is a duplex, west is unit 1, East is unit 2

via StreetComplete 52.0

Attached photo(s):
https://westnordost.de/p/144967.jpg

Duplex here

via StreetComplete 60.0

Attached photo(s):
https://streetcomplete.app/p/254838.jpg
https://streetcomplete.app/p/254839.jpg

Please verify how these streams interact.

This building and the accompanying yard are labeled "historical site" in planning documents for the area (e.g. the River Walk Ranch subdivision master plan), but I can't seem to find any list of it in the historical register or any local who knows the significance of it. The silo to the south (which is a local landmark) is NOT labeled such.

In context of overlay "Surfaces" – Long Pond Street (Residential Road) – way/1343595931 via StreetComplete 60.0:

This road is Coffee Pond Avenue. I want a coffee pond the size of a street!

Attached photo(s):
https://streetcomplete.app/p/254138.jpg
https://streetcomplete.app/p/254139.jpg

End of fence

via StreetComplete 59.3

End of fence

via StreetComplete 59.3

End of fence

via StreetComplete 59.3