Rivers and streams are often characterized as the lifeblood of the surrounding landscape.
The power of flowing water shapes the landscape and creates the watersheds that define community and regional identities. Water quality and quantity in western rivers supports fish and wildlife, agriculture and industry, recreation and sport.
The 15 miles of the Lower Blue River is not a naturally operating river system. The natural river corridor has been altered by multiple reservoirs comprising 5,337 surface acres in a 600 square mile watershed. The Dillon and Green Mountain Reservoirs store and supply water for residential, agricultural, environmental and recreational uses. Their operation includes trans-basin diversions to the Eastern Slope of Colorado. As a result, the periodicity, frequency and intensity of flows in the Lower Blue River have changed greatly from the natural flow cycle before dam construction.
Nevertheless, the Lower Blue River corridor provides habitat for a multitude of wildlife, from moose and otter to bald eagle and migratory waterfowl. Fish in the Lower Blue include naturalized brown trout, which spawn in October and November, and rainbow trout, which spawn throughout the spring, but do not successfully reproduce due to the presence of whirling disease. The vegetation along the Lower Blue is also unique. In its Survey of Critical Biological Resources for Grand County in 2006, the Colorado Natural Heritage Program found a narrowleaf cottonwood/water birch vegetation community along the river that was of significance to global biodiversity.
The Lower Blue River also carries the designation of Gold Medal Trout Waters by the Colorado Division of Wildlife, which is no small accomplishment for a non-natural river. The river has also provided water for agricultural production since European settlement, and decreed water rights have been diverted since at least the late nineteenth century. The river also provides opportunities for many recreationists, from float fishing to kayaking. Clearly, the Lower Blue River forms a key part of the identity of both Blue Valley Ranch and the local community.
Management of the river has focused on restoration, enhancement, and mitigation of the impacts of flow regimes.
Wetland and riparian habitat along the Lower Blue has been depleted in part due to the damming of the river upstream. As a result, restoration and expansion of the river floodplain was an important goal for the ranch's river restoration plan. Providing habitat for fish at all stages of their life cycle is a challenge with an altered flow regime, but a priority in order to maintain a viable fishery. Eroding river banks must be stabilized to protect fish habitat if natural flooding events are no longer sustained. Habitat restoration and enhancement for other river species such as otter, eagle and moose were necessary if those species were to be a permanent presence again.
Another key component in the river restoration program was establishing a continued monitoring program. This includes monitoring the health of macro-invertebrates like mayfly, caddisfly and stonefly, which are what make the fish in the Lower Blue worthy of Gold Medal status. Monitoring protocols are used to watch for nuisance aquatic species such as Zebra mussels, New Zealand mud snails and Dydimo. Identification tags on individual fish help to keep track of fish growth trends and movements, and recreational use and catch rates are tracked. Finally, river temperatures and flows are continually recorded to compare with trends in the health of fish and macro-invertebrates.
A long-term project that has been in progress for longer than any of the ranch's other programs.
Efforts have included the stabilization of the river channel along 4 miles of the Lower Blue using various types and shapes of river structures. These structures provide fish habitat and help to increase the depth/width ratio of the river, which lowers water temperatures during the hottest part of the summer when flows are low, while still allowing fish to travel upstream and boats to travel downstream unimpeded. Over 3 miles of off-channel spawning and fish rearing habitat was restored, including gravel bars, logs for cover, and trees and willows for shade. Five abandoned gravel pits and 5 former trout hatchery ponds were reclaimed and expanded to create brood ponds for fish. Finally, several hundred acres of wetland-riparian areas and waterfowl habitat were restored along the river's floodplain, which were formerly in hay production.
All of these improvements have resulted in a complicated and extensive system that requires constant maintenance and monitoring. Maintaining water levels in the off-channel system of ponds, canals and waterfowl impoundments is a challenge, particularly during rapid fluctuations in river flows. Ice often builds up on regulatory structures in winter, and leaves and other trash must be cleared during the summer and fall months. A comprehensive annual maintenance schedule and operations manual helps to keep the system running smoothly and accommodates future directions
The truest testament to any habitat work is the response from the wildlife and vegetation that the habitat work was targeting.
Moose were formerly a transitory species, spotted while on their way through the area and seldom staying longer than a few weeks. Now, a dozen individuals stay through the entire growing season, and a handful have become permanent residents. Migratory waterfowl of all species make stops in their north-south migrations in both the spring and fall. Two nesting pairs of bald eagle make their home along the lower reaches of the Blue. Colorado River otters are a regular, though fleeting site, blue heron have established a rookery in the cottonwoods, and a flock of Merriam's turkey now winter along the river every year.
Monitoring of the fishery program has shown a steady increase in fish standing crop, meaning that the river is supporting more fish than before. Sampling of macro-invertebrates like caddisfly and mayfly, as summarized with a Biotic Condition Index, continually showed scores in the "Good" to "Excellent" range until a dip in 2005, most likely caused by a proliferation in a native species of algae known as Didymo or "rock snot". Continued monitoring will help in understanding the long-term impact to the fishery.