Mountain Mutual Reservoir Company (MMRC) and North Fork Associates were established in 1980 to provide water rights that were reliable and available 365 days of the year for small Plans for Augmentation. 

After the Colorado Legislation passed Senate Bill 35 requiring any sub-division with lots smaller than 35 acres to replace water consumed on the lots with uncommitted water rights it was difficult for the developer to find water rights in the small quantities that were needed.  Ronald Blatchley realized the need of an entity to sell to the developer the exact amount of water rights that would be needed.  Thus a partnership known as North Fork Associates was established with initial assets of a full interest in 1.5 cubic feet per second (cfs) of the Guiraud 3T Ditch (G3T) and five shares of the Jefferson Lake Ditch Company (subsequently exchanged for 80 acre feet (af) of water from Spinney Mountain Reservoir).  The G3T water with an Appropriation Date of July 1 1867 was quantified to yield 21.825 af of consumptive use water for each 1.0 cfs.  This provided a “firm yield” that could be used for replacement of depletion's within the South Platte River drainage area from May through September of each year.  The “firm yield” of the Spinney Mountain Reservoir could be used for the other seven months of the year.
The G3T Ditch historically irrigated grassland in Park County in the drainage of the Middle Fork of the South Platte River.  All of these rights were subsequently sold to approximately 28 different entities for use in nearly all of the drainage's of the South Platte River, primarily above Denver.  Spinney Mountain Reservoir, owned by the City of Aurora is located on the South Platte River in southeastern Park County.
 It was envisioned that the requirement of a potential purchaser of water might be as small as one lot with a single-family dwelling, which would require only 0.0314 af of consumptive use water per year.  This would equate to the need of 0.0006 cfs of the G3T water and 0.0183 af of the Spinney Mountain Reservoir yield.  These minute amounts would be difficult to administer and would therefore not be acceptable to entities involved.  To circumvent this problem an organization could be formed in perpetuity to hold the interest in the water rights and then issue shares to equate to the amount of water rights needed.  Thus Mountain Mutual Reservoir Company was formed to accomplish this requirement.  The principal purposes of the Company are:  (a) to receive and hold title to direct flow and storage water rights, reservoirs and interests therein, lands, easements, rights-of-way, and other related facilities in trust for the members; (b) to adjudicate water rights and exchanges and to seek quantification of the historic consumptive use of water rights; (c) to administer water rights, operate water exchanges and operate facilities for the benefit of the members; and (d) to administer members' decreed plans for augmentation.
Each share is equivalent to the annual depletion of water in a single family house based on 3.5 capita per house using 80 gallons per day per capita and 10% loss using a non-evaporative septic system or 0.0314 of an acre foot equals 1.0 shares of MMRC stock.