Enhancing Water Quality and Dredged Material for the Port of Harlingen (Phase I)
Project Description
Maintaining and protecting the water quality of the Lower Laguna Madre, an important nursery for fish, shrimp and crab and a popular site for recreational fishing and boating, is imperative for the health of the Texas coast. However, the low dissolved oxygen (DO) concentrations in the Arroyo Colorado, the primary source of freshwater for the Lower Laguna Madre, have killed millions of fish over the past few decades. Most of these fish kills occurred in the tidal segment of the Arroyo, which directly flows into the Lower Laguna Madre. To address the DO impairment, the Arroyo Colorado Watershed Partnership (Partnership) developed the Arroyo Colorado Watershed Protection Plan (WPP), a comprehensive watershed-based strategy to improve water quality and aquatic and riparian habitat in the Arroyo Colorado. One of the top strategies for water quality improvement identified in the WPP is the construction of wetlands for removal of nutrients. Therefore, the Port of Harlingen and the Texas Water Resources Institute (TWRI) will construct a wetland to remove nutrients from spoils dredged from the turning basin at the Port of Harlingen, Texas.
The Port of Harlingen is located in the heart of the impaired tidal segment of the Arroyo Colorado, which is classified by the Texas Commission on Environmental Quality as the segment between the confluence with Laguna Madre in Cameron/Willacy County to a point 100 meters (110 yards) downstream of Cemetery Road in Cameron County. This part of the water body is also defined as a coastal natural resource area (CNRA) and a coastal wetland in the Coastal Coordination Act. The location of the wetland is on an approximately 35 acre site where dredge spoils from the turning basin were previously dumped downstream of the Port of Harlingen on the northwestern bank of the Arroyo Colorado. By impacting this key location within the Arroyo Colorado, the resulting water quality improvements will positively affect the water quality within the Lower Laguna Madre maintaining its health as a vital coastal nursery and ecological and economic resource.
Funding will address two major funding categories and goals within the Coastal Management Program: water quality and quantity improvements and enhancement of critical areas. Water quality issues associated with the Arroyo Colorado and the Lower Laguna Madre will be addressed through the construction of an approximate 35-acre wetland that will be designed and built to protect critical habitat and provide nutrient removal from dredge spoils from the turning basin from the Port of Harlingen. The spoils contain nutrients from two sources: 1) nonpoint source pollution during Port activities (loading, unloading, stormwater runoff) and 2) detachment from upstream sediment that settles out of the water column in the turning basin (a wider, deeper segment of the stream that has slower flow). By removing these nutrients, the spoils can be purchased and used as beneficial amendments in other areas of the watershed, which will provide revenue for sustaining the sediment basin and wetland system. In addition to improving water quality
Funding Source
Funding provided by General Land Office as part of the Costal Management Program.