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Union Pacific Railroad Causeway

The twenty-mile Union Pacific Railroad (UPRR) causeway across the Great Salt Lake separates the lake into a North Arm and South Arm that contain different levels of salinity. Between 2011 and 2013, UPRR applied to the U. S. Army Corps of Engineer (USACE) for approval to close two culverts in rock-fill causeway that were at risk of collapse. Several agencies, including the Division of Water Quality (DWQ), expressed concerns about potential changes to the lake’s ecological resources from culvert closure. In response, UPRR proposed construction of a 180-foot bridge intended to replicate the water and salt transfer previously accomplished by the free-flowing exchange of the lake water through the culverts. After completing water and salt balance modeling for the lake, UPRR determined that a 150-foot bridge would better duplicate the water-salt exchange accomplished by the culverts.

The Division’s top priority remains to protect existing uses for the Great Salt Lake and maintain the lake’s water quality. DWQ will be working closely with the USACE, USEPA, Utah Forestry, Fire and State Lands (FFSL) and UPRR to ensure that any changes to the causeway won’t disturb the fragile balance of the Great Salt Lake ecosystem.

Great Salt Lake Causeway

Great Salt Lake Causeway.Built in the late 1950s, the twenty-mile rock and earthen fill causeway replaced a wooden trestle bridge that was part of the east-west Lucin cutoff rail route to California. Two culverts beneath the causeway, installed to facilitate boat traffic between the northern and southern arms of the Great Salt Lake, have allowed some water flow between the two lake sections, although significantly less than with the wooden bridge. The two concrete box culverts have deteriorated and settled into the lake bed, requiring UPRR to either replace them or fill them in to maintain the integrity of the causeway. Note: Click image to see full size view.


The Division of Water Quality is responsible for certifying that federal permits issued by the Corps of Engineers meet state water quality standards and comply with Section 401 of the Clean Water Act. DWQ issues 401 Certifications for individual (404 permits) and nationwide permits (NWP) by the Corps.

In 2011, UPRR contacted the Corps to request a national permit (NWP-14) to close the two failing culverts and replace the current causeway with a new 180-foot long concrete pile supported bridge. DWQ raised concerns at that time about the size and placement of the bridge, the impacts to water quality from different water flow patterns, and the probable changes in salinity concentrations in the northern and southern arms of the lake from the causeway closure and proposed bridge. From 2011 to 2012, the Corps, UPRR, and DWQ held a series of discussion on water quality concerns surrounding the UPPR proposal. In August 2012, the Corps granted UPRR an emergency permit to fill in the western culvert, which the railroad subsequently closed November 2012.

In early November 2013, UPRR contacted the Corps to request an emergency determination for the closure of the east culvert. The Corps was not persuaded an emergency existed and denied the emergency permit. Based on information it received from UPRR in late November 2013, the Corps gave the railroad authorization to stabilize the east culvert temporarily through an NWP-14 permit, but required UPRR to monitor water quality and develop contingency plans for mitigation to avert degradation of the water resource. UPPR subsequently submitted a completed application for a 401 Certification to DWQ on December 10, 2013.

On December 16, 2014, UPRR requested that DWQ temporarily withdraw the railroad’s January 7, 2014, application for a 401 Certification. UPRR stated that it will provide DWQ with documentation of compliance with the State of Utah’s antidegradation policy and a revised Compensatory Mitigation and Monitoring Plan (CMMP) on January 7, 2015 for division review.

DWQ has agreed to withdraw the application and reinstate it on February 11, 2015. The 30-day public comment period on the Draft Cert will begin on January 21, 2015 and ended on February 20, 2015.

Public Comment

DWQ provided a 30-day public comment period for the following documents:

  • Proposed 401 Water Quality Certification,
  • Proposed Compensatory Mitigation and Monitoring Plan
  • Level I Antidegradation Review to Permanently Close the East Culvert of the Union Pacific Railroad Causeway
  • Level II Antidegradation Review to Temporarily Close the East Culvert of the Union Pacific Railroad Causeway

The division received responses from the following stakeholders during the public comment period:

DWQ prepared a Response to Public Comments to address specific concerns and comments from stakeholders, provide information on the 401 Cert program, and explain UPRR plans for this project. UPRR also provided a Response to 401 Cert Public Comments.

401 Water Quality Certification with Conditions

On March 2, 2015, DWQ issued approval to UPRR for a 401 Water Quality Certification with Conditions. This document certifies that UPRR has provided reasonable assurances that any discharge associated with the permanent closure of the East Culvert of the Great Salt Lake causeway will not violate surface water quality standards or cause additional degradation in surface waters not presently meeting water quality standards.DWQ approval to permanently close the UPRR Causeway is subject to specific conditions enumerated in the 401 Cert.

Culvert Closures

The imminent threat of failure of the east culvert along the Union Pacific Railroad (UPPR) causeway prompted the U.S. Army Corps of Engineers (Corps) and the Utah Division of Water Quality (DWQ) to issue separate permits for the temporary closure of the culvert. This temporary closure was granted as a safety measure for rail traffic on the causeway across the Great Salt Lake.

The Division of Water Quality has issued a draft 401 Water Quality Certification for the temporary closure of the culvert on December 13, 2013. DWQ issued a signed 401 Water Quality Certification on December 16, 2013, along with public comments it received between December 13 and December 16, 2013.

The public comment period for the certification ran from December 12, 2013 to January 15, 2014. Although DWQ issued the certification prior to the close of the full comment period for safety reasons, the Division retained the option to modify the draft 401 Certification based on the comments it received from the public.

Water Quality Concerns

The Division expressed concern that closure of the causeway and construction of a new bridge could alter the water quality and beneficial uses of the Great Salt Lake. The causeway has acted as a barrier to the natural water flow patterns in the lake for over fifty years, creating pronounced differences in the salinity levels in the northern and southern sections. While the southern arm still receives freshwater from the Jordan, Bear, and Weber rivers, the causeway blocks water flows into the northern arm. As a result, salinity levels in Gunnison Bay north of the causeway are much higher than those in Gilbert Bay to the south.


The east and west culverts allowed for some water movement between these two sections of the lake. Closure of the east culvert would prevent this water mixing. It is currently unclear what effect this change to the water flow would have on the Great Salt Lake ecosystem and its beneficial uses.

To address the uncertainty around possible impacts to the water quality of the lake from these proposed changes, DWQ requested that the Corps include certain conditions on its permit for the railroad’s causeway project:

  • DWQ may modify its 401 Certification based on information received during the public comment period.
  • Approval to temporarily reduce the water circulation between Gunnison and Gilbert Bays previously provided by the east culvert will end on March 21, 2014. UPRR must submit information prior to that date that DWQ will use to determine whether the water quality impacts from the closure are indeed temporary. If the Division determines that the impacts are not temporary, UPRR will be required to conduct a Level II anti-degradation review for DWQ approval to ensure that existing uses and water quality are maintained.
  • UPRR will submit an interim monitoring plan within 30 days of the Director of DWQ signing the 401 Certification.
  • UPRR will model and report potential water quality impacts from the closure of the east culvert, including an independently verified water and salt balance model.
  • UPRR will submit plans for any changes to the causeway that could impact the water circulation between Gilbert and Gunnison Bays to the Director of DWQ for review.

Temporary-Closure Permit

The current Corps permit covered the temporary closure of the east culvert only. The Corps will evaluate permanent repairs to the causeway, including construction of a bridge, through a standard individual permit. The Corps issued a public notice on UPRR’s proposal for a permanent solution on December 13, 2013, and provided opportunities for public comment.

Because DWQ’s draft 401 Certification also covers the possible construction of a bridge to replace the causeway, the Division attached a number of conditions to its certification:

  • UPRR must submit an interim monitoring plan to DWQ within 30 days of the 401 Certification;
  • within 90 days of certification, DWQ will hold a 30-day public comment period on the interim monitoring plan;
  • interim monitoring will start no later than May 2014;
  • UPRR must submit results from the interim monitoring for DWQ approval within 90 days of monitoring; and,
  • UPRR must submit a mitigation and modeling plan for DWQ approval. There will be a minimum 30-day public comment period.

Interim Monitoring

UPRR conducted interim monitoring in the Great Salt Lake to meet requirements of the USACE Nationwide Permit and the DWQ 401 Water Quality Certification. Interim monitoring focused on characterizing the open waters of Gilbert Bay and Gunnison Bay near the project site.

Monitoring results included data for the four elements of the interim monitoring plan (IMP):

  • Surface water elevation data from the concurrent monitoring period
  • In-situ water profiles for temperature and other parameters
  • Water quality samples for metals and other analyses at an off-site lab
  • Brine shrimp samples for metals analyses, counts, and taxonomic identification.

These reports document the samples collection and lab analysis of samples but do not provide interpretation of the data, with the exception of the Annual Report.

Interim Monitoring Reports for 2014, 2015 and 2016

2014 Annual Monitoring Report

The Annual Report, submitted on December 19, 2014, reviewed and summarized the ambient lake monitoring results for the monitoring events conducted in 2014. Summaries of data collected included water surface elevation, in-situ vertical water profiles, surface water chemical analyses, brine shrimp metal analyses, and data quality assurance with the IMP’s Quality Assurance Project Plan (QAPP).

UPRR Proposed Comprehensive Mitigation and Monitoring Plan (CMMP)

In April 2013, UPRR undertook a major re-evaluation of possible impacts from culvert closure and bridge construction. On July 25, 2014, UPRR submitted a comprehensive plan that included modeling to evaluate the effects of the project on the water and salt balance and reexamine UPRR’s 180-foot bridge proposal to ensure that it served the same water-mixing functions as the closed culverts. The CMMP is currently under review by DEQ, USACE, USEPA and FFSL. As conditioned in the current 401 Water Quality Certification dated December 16, 2013, DEQ will release the CMMP for a minimum 30-day public comment period once it completes its agency review.

UPRR’s original compensatory mitigation plan was to construct a 180-foot-long bridge with a causeway opening that would replace the aquatic functions provided by the east and west culverts before they were closed. At that time, USACE authorized construction of the bridge subject to UPRR’s submission and USACE’s and UDWQ’s approval of a final compensatory mitigation and monitoring plan. This proposed CMMP replaces the UPRR mitigation and monitoring plan proposed to and rejected by USACE in 2013.

Causeway Construction Progress

UPRR's contractor commenced construction on the causeway bridge in November 2015, with completion scheduled for September 2016.

These reports provide a brief summary of construction activities related to the construction schedule submitted to the regulating agencies and included in the Compensatory Mitigation and Monitoring Plan (CMMP)

Supporting Documents

Antidegradation (ADR) Review

DWQ’s antidegradation (ADR) policy protects existing instream uses and high quality waters. While this policy does not necessarily prohibit degradation of water quality, it does create a series of rules that ensure that degradation is minimized if a project is necessary for social or economic development. Level I ADR reviews are intended to ensure that the action will not degrade existing beneficial uses. Level II reviews are conducted to protect designated uses for waters where the water quality is better than the criteria.

Temporary Closure of the East Culvert

On December 10, 2013, UPRR submitted a revised application to DWQ for the 401 Certification (Cert) for the temporary closure of the east culvert. As part of its 401 Cert application, UPRR submitted a Level I ADR Review Form and requested a Level II exclusion on the grounds that the water quality impacts would be temporary and limited. DWQ determined that the water quality impacts would be indefinite because the proposed bridge was in the planning phase and UPRR had not yet secured the necessary easements to begin construction. On the basis of this determination, DWQ required UPRR to submit a Level II ADR Review for degradation that might occur during the interim period prior to the establishment of permanent mitigation.

Permanent Closure of the East Culvert

UPRR is seeking authorization to make permanent the temporary emergency closure of the east culvert and to construct a new opening in the railroad causeway to mitigate the water quality impacts to the Great Salt Lake from the closure of the east and west culverts. UPRR submitted supplemental information to DWQ for the Level I ADR Review for permanent closure of the east culvert and bridge construction based on UPRR’s reevaluation of the Level I ADR review and the factors it used to justify a Level I determination.

Bridge Evaluation

On June 2, 2014, UPRR submitted its Bridge Evaluation Report. This report looked at various bridge sizes on the water and salt balance between the North and South Arms and compared these effects to the culvert simulation. Based on the findings in this report, UPRR proposes to construct a 150-foot bridge with an invert elevation of 4,183 feet to best match the lake salinities and salt loading achieved by the culverts.

Resource Assessment

On July 1, 2014, UPRR submitted its Resource Evaluations, Causeway Culvert Closure and Bridge Construction Project report. The Resources Evaluations report assessed the potential effects of the proposed bridge project on the lake ecosystem. The report considered the environmental consequences of the four bridge alternatives on the following areas of concern:

  • Biological Resources
  • Deep Brine Layer
  • Lake Circulation 
  • Mercury and Methylmercury
  • Water Chemistry
  • Water Quality

Water and Salt Balance Modeling

During the review process, federal and state agencies expressed concerns about the impacts of the bridge project and requested that the UPRR use the U.S. Geological Survey’s (USGS) Water and Salt Balance Model of the Great Salt Lake (GSL) to evaluate the impacts on aquatic functions in the GSL from replacing the closed culverts with a 180-foot bridge. UPPR reevaluated potential project impacts and ran models to see which bridge configurations would best replicate the water and salt transfer between the North Arm and South Arm of the lake prior to culvert closures. UPRR conducted a three-step modeling plan that simulated conditions for the following two conditions:

  • Culvert Simulation
    Simulated conditions for the east and west culvert before closure of the west culvert in 2012
  • Proposed Bridge Simulation
    Simulated conditions for the proposed bridge

The 180-foot bridge simulation resulted in higher salinity levels in the South Arm than the culvert simulation. Based on modeling results, UPRR evaluated adjustments to the proposed bridge to more closely mimic the function and effect of the closed culverts on the water-salt balance between the two arms of the lake.

On April 4, 2014, UPRR submitted its Final Water and Salt Balancing Model along with a transmittal letter to DWQ. The modeling report summarized the results of UPRR’s three-step modeling efforts. A number of agencies subsequently submitted comments on the report:

On August 22, 2014, UPRR submitted a response to DWQ modeling comments along with supplemental information requested by DWQ and the USGS that further characterized the results as well as the uncertainty of the water and salt balance model.