Lake Purdy's inlet is still listed with no cleanup plan

Karst valleys move water fast. Rain falls onto limestone and dolomite bedrock and travels through dissolved channels into springs and streams with almost no natural filtering along the way. That structural vulnerability shows up plainly in the official impairment record for the Southern Limestone/Dolomite Valleys and Low Rolling Hills.¹ Shades Creek and Patton Creek are both listed as impaired under the Clean Water Act with a completed cleanup plan — a TMDL, which sets an enforceable ceiling on how much pollution the waterway can carry.¹ Fivemile Creek is listed as impaired but with other controls expected to address the problem instead of a TMDL.¹

The Little Cahaba River sits in a different spot on that same list. Its Lake Purdy segment (AL03150202-0103-102) is documented as impaired and 303(d)-listed as requiring a TMDL, with no cleanup plan completed.¹ The adjoining upstream segment of the same river is assessed as fully supporting all its designated uses — so the problem is specific to the reservoir end, not the whole stream.¹ That distinction isn't a technicality: until a plan is finalized, there's no binding limit on the pollutant loads reaching that segment and no timeline for improvement. Lake Purdy is also understood to supply drinking water to part of the Birmingham area, which makes the unresolved status at its inlet worth watching rather than filing away.

It's tempting to attach a named discharger to that gap, and worth saying plainly that the record doesn't support one. The facility EPA currently lists in significant non-compliance nearest this write-up, FIREROCK PRODUCTS, LLC, sits at 33.4986, -86.9111 — west of Birmingham, in the Village Creek drainage that flows to the Locust Fork and the Black Warrior, a different river basin from the Cahaba.² Its violation is also administrative rather than chemical: a required discharge monitoring report was never submitted, with no pollutant exceedance on file.² That's a real compliance failure, but nothing in the record connects it to water reaching Lake Purdy, and it shouldn't be read as a source there.

What the geology does support is a general caution. Fast-draining bedrock means whatever loads do enter this system reach surface water and springs quickly and with little dilution, so the absence of an enforceable limit matters more in a karst valley than it would where deeper soils and slower runoff buffer the inputs. Identifying what is actually loading the Lake Purdy segment would take the TMDL that hasn't been written yet — which is the point. Until then, the drinking water inlet is the one impaired water here without a ceiling on it, and without a documented cause on the public record either.