New Egg Incubation Water Reuse - Chiller System Team
Kooskia National Fish Hatchery, Fish and Wildlife Service, Idaho
Point of Contact
Kooskia National Fish Hatchery (NFH) constructed a new egg incubation system that saves energy and reduces well water use. Historically, Salmon eggs at Kooskia NFH were incubated for 5 months using a single-pass system with chilled well water. The existing chiller was oversized in order to also accommodate summer operations such that half of the chilled water was wasted prior to reaching the egg incubators. To address this issue, the existing egg incubation recirculation system was rebuilt, increasing efficiency by reusing chilled water, which reduced the required chilling capacity by over 80 percent, from 150 gallons per minute (gpm) to 25gpm. A new water reservoir with increased capacity was constructed to provide the system thermal stability and provide extra alarm response time during a loss-of-flow event. A more efficient chiller was added that was 90 percent smaller than the original chiller, and a passive heat exchanger using ambient creek temperature to pre-chill well water was installed. The 25 horsepower production wells were also rehabilitated with new, more efficient 2 hp pumps. These measures have reduced electricity use by 65 percent, thereby saving $32,875 annually and reducing annual greenhouse gas emissions by 297 MT of CO2e.
Kooskia National Fish Hatchery (KNFH) spring Chinook salmon (SCS) culture program begins when adult salmon return to Clear Creek and enter the hatchery trap from May through August each year. Spring Chinook salmon are collected from the Kooskia trap and transported to Dworshak National Fish Hatchery (DNFH), 34 miles west, where spawning occurs in late August. The eggs remain at Dworshak NFH until they reach the eyed stage, when the eggs are picked, enumerated and transferred back to KNFH for incubation, rearing, and release to Clear Creek the following April. The Kooskia NFH production goal is 600,000 SCS at 18 - 20 fish per pound (fpp) or approximately 5.5 inches at release. Eyed eggs begin incubation in October using well water that is chilled to approximately 38 degrees F.
Since 2001, Clear Creek water has been used from November to February instead of using chilled well water. At that time of year, the Creek water temperatures are cooler than the chilled well water. This allows the hatchery to conserve energy by not running the well pumps and chiller. Eggs are not treated for fungus control, but both eggs and sac fry are picked clean weekly to prevent any fungus invasion. Temperature Units are closely monitored. Upon hatching, sac fry remain in incubation trays until completely buttoned up and then placed into rectangular nursery tanks. Nursery rearing begins in the outside nursery tanks using the reuse system with well water makeup. Once fry outgrow the tanks, they are transferred to the Burrow’ s ponds (BPs, app. 200 fpp). Fish are inventoried and tagged in July by the marking trailer crew. The reuse system and chiller are used from June through September to maintain system temperatures of approximately 50 degrees Fahrenheit. Clear Creek water temperatures are generally too high for healthy Chinook rearing during those summer months.
Also, use of well water decreases the introduction of the creek water parasite ICH into the reuse system. Kooskia has a limited amount of well water available. Two production wells produce a maximum of 450gpm, each approximately 57 degrees Fahrenheit. When Clear Creek water temperature lowers around October, the well water is shut down and single pass Clear Creek water is run through the BPs. During most years, the fish will be reared in the six BPs and split into the raceways in January. Fish remain in BPs and raceways until they are released as smolts directly into Clear Creek the following April.
Results and Achievements
Electrical use during egg incubation was reduced from approximately 155,000 KWH per month to approximately 54,000KWH per month. Over the five month incubation period, this represents a savings of approximately 505,000KWH. At $.0651 per KWH this represents an annual savings of $32,875.00 for the station. Using the US Department of Energy average of 1.297 lbs. of CO2 per KWH, this represents an annual CO2 emissions reduction of 654,985lbs. Reducing the egg incubation well water use from 150 GPM to 25 GPM over the 5 month incubation period equals a total water savings of 27,000,000 gallons of water annually.
The project described is unique to this facility, however, the process used to reduce energy consumption through increased efficiency of thermally treating water could be used at other facilities with a high water consumption.