Irrigation districts suffer from many negative impacts of aquatic vegetation including reduced storage capacity in reservoirs, hydroelectric production interference, distorted canals design features, degraded recreational uses, and reduced water quality and wildlife habitat value. With temperatures reaching record highs this year, vegetation is growing fast and thick, which can affect water movement throughout a canal.
“Pondweeds limit capacity in laterals while algae buildup can plug screens and pumps,” said East Columbia Basin Irrigation District Water Quality Supervisor Jamie Balliet. Like any water project, the Columbia Basin Irrigation Districts, located in Eastern Washington state, must deal with aquatic vegetation.
The districts use aquatic herbicides and algaecides for control of plants and algae. And on top of the headache of dealing with the extreme vegetation, there are permitting laws on what chemicals can be used and how they can be applied. These guidelines are established by National Pollutant Discharge Elimination System (NPDES) permits in compliance with the Clean Water Act.
“These guidelines require that any chemical used must be at or below a predefined concentration at a designated point of compliance,” Balliet said. “The State Department of Ecology (DOE) considers a point of compliance as the location where water treated with pesticides enters surface water bodies that existed prior to creation of reclamation and irrigation projects. To ensure we meet our chemical tolerances at a point of compliance, often times we are required to apply chemicals at a lower rate than the chemical label suggests, lowering efficacy.”
Balliet said the limitations can become problematic on the lower end of laterals, near the compliance sites, where dilution and the distribution of chemicals lack sufficient distance to take effect.
For the Columbia Basin Irrigation Districts, the NPDES permits are a fairly new limitation. On March 12, 2001, the Ninth Circuit Court of Appeals decided application of an herbicide in compliance with the labeling requirements of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) did not exempt an irrigation district from needs to obtain a NPDES permit. This requirement came after the Talent Irrigation District (in southern Oregon) applied the herbicide Acrolein to an irrigation canal and a leaking waste gate led to a fish kill.
Headwaters Inc. and Oregon Natural Resources Council filed a Clean Water Act citizen suit against the irrigation district for applying the herbicide into a system of irrigation canals. The Ninth Circuit then held a decision that irrigation districts obtain NPDES permits and that irrigation ditches were ‘waters of the United States’ under the Clean Water Act.
Washington is a regulated state meaning the Washington State Department of Ecology has been delegated authority by the Environmental Protection Agency to implement the Clean Water Act and provide the NPDES permits to irrigation districts. Each permit lasts for five years and then must be renewed. During the time of renewal changes can be made to the permit. DOE may modify this permit to impose new or modified numerical limitations, if necessary, to meet Water Quality Standards for surface waters, sediment quality standards, or Water Quality Standards for ground waters, based on new information obtained from sources such as inspections, effluent monitoring, or Department-approved engineering reports. The current permits for the three Columbia Basin Irrigation Districts expire June 2017.
“You have to be careful when you ask for change because it might not always be in your favor,” said Quincy Columbia Basin Irrigation District Water Quality Manager Craig Gyselinck. “However, if I were to ask for change it would be for more [a bigger variety of] herbicides. We are very limited as to the amount of herbicides we can use.”
Balliet said the districts are limited on types of herbicides but also the amount they are allowed to use. He said there has been discussion on wanting change on “holding time allowances”: the amount of time the district is allowed to hold a pollutant in the laterals before it reaches a point of compliance.
“There are certain chemicals our permit allows us to use but we can’t because the recommended holding time is too high for the permit,” Balliet said. “We have to make sure the concentration of the chemical and the holding time meets standards. For example we may have a chemical that has a holding time of 24 hours but the permit requires the chemical to stay in the water for 96 hours before reaching the compliance point. You would need to build ponds and valves to stop flow but that doesn’t financially make sense.”
Although the new permit has created an increase in staff time and aquatic weeds for the districts, the water quality managers do see a bright side. “The permit protects us and shows that we are being environmentally responsible. But it is an ongoing process,” Gyselinck said. “One of the things I worry with the new permit, with the new water quality standards, we might have even stricter limits than we already have.”
Before the new permit is finalized, a comment period will be held. Balliet said changes are possible, but for the most part, the permit stays the same.
“We are only allowed to discharge under the guidelines of the NPDES permit so we are stuck with them [current guidelines],” Balliet said.