State water scientists present draft E. Coli TMDL for Castle Creek, urge septic and land-use action

Sam Taylor, a TMDL and watershed planner with the Utah Division of Water Quality, told the Castle Valley Town Council on March 19 that the state’s draft total maximum daily load — known as a TMDL — for E. Coli in Castle Creek, Mill Creek and Pack Creek identifies a needed 14% reduction in E. Coli at the sampling points closest to the Colorado River.

Taylor said the draft consolidates roughly a decade of monthly sampling at five sites in Castle Creek, and that the 14% figure represents the reduction in the average E. Coli level the technical analysis indicates is needed. “Total maximum daily load (TMDL), think about that as the allowable amount of pollution in a creek,” Taylor said during his presentation.

Why it matters: the state lists waters with persistently elevated pollutant levels as “impaired,” which triggers more detailed study and planning. Taylor said the draft is nonregulatory: it assigns no permit-based waste load allocations to local sources, and the report’s intended role is to guide voluntary on-the-ground projects and to help communities seek funding for those projects.

What the draft finds and recommends: Taylor and his team identified on-site wastewater systems — failing or poorly functioning septic systems — and increased interaction between shallow groundwater and irrigation return flows as likely contributors to higher E. Coli counts in the lower creek reaches. The report looks across possible sources (livestock, wildlife, recreation, failing septic systems and agricultural return flows) and emphasizes septic and agricultural best-management practices as priority actions for Castle Valley.

Taylor described seasonal trends in the data: E. Coli values generally rise from May through a September peak and decline in October, a pattern he said is consistent across the sampling sites. He also contrasted Castle Creek with Mill and Pack creeks: Castle Creek’s needed reduction was smaller (about 14%) than the reductions identified elsewhere in the basin.

Funding and next steps: Taylor said the Division of Water Quality can help communities frame projects for nonpoint-source funding, citing EPA 319 and other federal sources and noting a state nonpoint-source program that is expected to continue. He said a stakeholder review of the draft opened in early March and that the division is accepting corrections and comments during that stakeholder period; Taylor said he and colleague Amy Dickey would be in the valley to meet with local stakeholders before the review closes and that the state intends to transmit the TMDL to the Water Quality Board for adoption in late June.

Local response and follow-up: Pam Hackley, who reviewed early drafts, and council members discussed the potential for additional targeted monitoring — for example, sampling directly below the Quaky Pond inflow and at locations where grazing or concentrated livestock movement could affect counts. Taylor and local health officials noted that drinking water issues (such as a boil-water notice at Castle Valley Academy referred to during the meeting) are handled by the local health department and were not part of the TMDL’s scope.

Taylor encouraged Castle Valley officials and residents to submit corrections and additional local data. He provided contact information for himself and Amy Dickey and said the division’s project manager for grants could help with funding questions.

Ending: The draft TMDL is positioned as a science-based roadmap to reduce E. Coli in creeks used for recreation and to help communities package projects for funding; local stakeholders asked for clarifications and more monitoring in specific locations before the state finalizes the plan.